An experiment covers many areas of human activity and is expressed in a controlled change in the conditions for the implementation of a phenomenon in order to study it.

Chemical experiment is important both in chemical science and in teaching chemistry. The origins of the school chemical experiment methodology were such famous methodologists as V.N. Verkhovsky, K.Ya. Parmenov, V.S. Polosin, L.A. Tsvetkov, A.A. Grabetsky and others.

Let us characterize the triune functions of a chemical experiment. The educational function is that students receive information about the properties of substances, the occurrence of chemical reactions, the methods of chemical science, and the formation of practical skills. Only in close interaction between experiment and theory in the educational process can high quality chemistry teaching be achieved.

The educational function of the experiment includes the formation of beliefs in the objectivity of scientific knowledge in the world, in the possibility of knowledge and transformation of the world.

A chemical experiment promotes the development of independence and increases interest in chemistry, because in the process of performing it, students become convinced not only of the practical significance of such work, but also have the opportunity to creatively apply their knowledge.

A chemical experiment develops students' thinking and mental activity; it can be considered as a criterion for the correctness of the results obtained and the conclusions drawn. A chemical experiment opens up great opportunities both for creating and solving problem situations, and for testing the correctness of the hypothesis put forward. During the experiment, students master general organizational skills in planning and monitoring their own activities. Consequently, the experiment has a positive effect on the development of students, and the teacher has the opportunity to control the processes of thinking, learning and knowledge acquisition.

Heuristic function chemical experiment manifests itself in the establishment of new a) facts; b) concepts and c) patterns.

Corrective function of a chemical experiment manifests itself in overcoming difficulties mastering theoretical material and bug fixes students. Very hour

Generalizing function of a chemical experiment allows us to develop prerequisites for constructing various types of empirical generalizations. Using a series of experiments, one can draw a general conclusion, for example, about the belonging of various classes of substances to electrolytes.

Research function of a chemical experiment most clearly manifested in problem-based learning.

Types of chemical experiment

There are educational demonstration experiment, performed primarily by the teacher on a demonstration table, and student experiment– it is carried out by students at their workplaces.

Demonstration experiment is carried out mainly when presenting new material to create in schoolchildren specific ideas about substances, chemical phenomena and processes, and then to form chemical concepts. It allows you to make clear important conclusions or generalizations from the field of chemistry in a short period of time, teach you how to perform laboratory experiments and individual techniques and operations.

The demonstration experiment is carried out in the following cases:

– it is impossible to provide the required amount of equipment at the disposal of students;

– the experiment is complex, it cannot be carried out by schoolchildren themselves;

– students do not have the necessary equipment to conduct this experiment;

– experiments with small amounts of substances or on a small scale do not give the desired result;

– experiments are dangerous (working with alkali metals, using high voltage electric current, etc.);

– it is necessary to increase the pace of work in the lesson.

The chemical demonstration experiment must meet following requirements:

– compliance with the goals and objectives of the lesson;

– visibility

– technical simplicity

As a rule, in chemistry the object of study is not the device itself, but the process occurring in it. The complexity of the device and unimportant details of the experiment should not distract students’ attention from the essence of the experiment.

– reliability: the experiment must proceed successfully, without failures, for this it is prepared in advance by the teacher; a failed demonstration experience undermines the teacher's authority. If the experiment still did not work out, you need to find out the reasons for the failure, eliminate them and demonstrate the experience in the next lesson.

– safety

Methods for ensuring the safety of an experiment include: cleanliness of glassware, preliminary checking of reagents, use of reagents in certain quantities, strict adherence to instructions on the experimental technique. If strong effects are expected during the experiment (flash, loud sound), then students are warned in advance.

Student experiment enriches students with knowledge; in the course of it, various skills and abilities are developed. General laboratory skills include: handling chemical glassware and instruments, performing laboratory operations (dissolving, dissolving, filtering, weighing, etc.), obtaining substances, collecting them, recognizing them. Organizational skills are also developed: planning an experiment, self-control, maintaining order in the workplace, etc.

The main types of student experiment include: laboratory experiments, practical classes, workshops. All of them represent types of independent work for students, involving the performance of chemical experiments, and differ primarily in didactic tasks.

Laboratory experiments carried out primarily to study new material or consolidate it.

Practical work have the main didactic task - improving and applying knowledge and skills, as well as their control, each student receives a mark for completing practical work and preparing a report.

Organization of a chemical experiment

A chemistry teacher must be able to plan an experiment on the entire topic and for a specific lesson, apply it methodically correctly, select experimental options, guide the cognitive activity of students, analyze and evaluate their own activities during demonstrations and the activities of students when they independently perform experimental work.

In thematic planning, in accordance with the curriculum, the sequence of demonstrations, laboratory experiments, and practical classes is established. Knowing in advance the timing of the experiment, the teacher has the opportunity to prepare equipment, teaching aids, etc. for lessons in advance.

When drawing up lesson plans, the teacher needs to think about at what stage of the lesson, in what sequence, with what reagents and instruments to conduct experiments, determine their place during the lesson depending on the significance of the tasks, as well as the form for recording the results obtained (figure, table, equation reactions, etc.).

The role of the teacher in practical work is to monitor the correct execution of experiments and safety rules, the order on the work table, and the provision of individually differentiated assistance.

Students' performance in practical work is assessed on the basis of a written report and observation results. Such criteria could be:

– error-free and accurate execution of experiments;

– correct recording of explanations, conclusions and reaction equations;

– skillful handling of reagents and equipment;

– quality of report design;

– compliance with safety precautions and discipline during classes.

The quality and strength of acquired skills and abilities depend on the frequency of their use in practical work.

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Such a complex but interesting science as chemistry always causes an ambiguous reaction among schoolchildren. The children are interested in experiments that result in the production of substances of bright colors, the release of gases, or precipitation. But only a few of them like to write complex equations of chemical processes.

The importance of entertaining experiences

According to modern federal standards, a curriculum subject such as chemistry has been introduced in secondary schools and has not been left without attention.

As part of the study of complex transformations of substances and solving practical problems, the young chemist hones his skills in practice. It is through unusual experiences that a teacher develops an interest in the subject in his students. But in regular lessons, it is difficult for a teacher to find enough free time for non-standard experiments, and there is simply no time to conduct them for children.

To correct this, additional elective and optional courses were invented. By the way, many children who are interested in chemistry in the 8th and 9th grades become doctors, pharmacists, and scientists in the future, because in such classes the young chemist gets the opportunity to independently conduct experiments and draw conclusions from them.

What courses involve fun chemical experiments?

In the old days, chemistry for children was available only from the 8th grade. The children were not offered any special courses or extracurricular chemical activities. In fact, there was simply no work with gifted children in chemistry, which had a negative impact on the attitude of schoolchildren to this discipline. The children were afraid and did not understand complex chemical reactions, and made mistakes in writing ionic equations.

Due to the reform of the modern education system, the situation has changed. Now in educational institutions they are also offered in lower grades. The children are happy to do the tasks that the teacher offers them and learn to draw conclusions.

Elective courses related to chemistry help high school students gain skills in working with laboratory equipment, and those designed for younger students contain bright, demonstrative chemical experiments. For example, children study the properties of milk and become familiar with the substances that are obtained when it sours.

Experiences related to water

Entertaining chemistry is interesting for children when, during the experiment, they see an unusual result: the release of gas, a bright color, an unusual precipitate. A substance such as water is considered ideal for conducting a variety of entertaining chemical experiments for schoolchildren.

For example, chemistry for 7-year-old children can begin with an introduction to its properties. The teacher tells the children that most of our planet is covered with water. The teacher also informs the students that in a watermelon there is more than 90 percent of it, and in a person it is about 65-70%. After telling schoolchildren how important water is for humans, you can offer them some interesting experiments. At the same time, it is worth emphasizing the “magic” of water in order to intrigue schoolchildren.

By the way, in this case, the standard chemistry set for children does not involve any expensive equipment - it is quite possible to limit yourself to affordable devices and materials.

Experience "Ice Needle"

Let us give an example of such a simple and at the same time interesting experiment with water. This is the construction of an ice sculpture - a “needle”. For the experiment you will need:

• water;
• salt;
• ice cubes.

The duration of the experiment is 2 hours, so such an experiment cannot be carried out in a regular lesson. First you need to pour water into an ice tray and place it in the freezer. After 1-2 hours, after the water turns into ice, the entertaining chemistry can continue. For the experiment you will need 40-50 ready-made ice cubes.

First, children must arrange 18 cubes on the table in the form of a square, leaving a free space in the center. Next, after sprinkling them with table salt, they are carefully applied to each other, thus gluing them together.

Gradually all the cubes are connected, and the result is a thick and long “needle” of ice. To make it, just 2 teaspoons of table salt and 50 small pieces of ice are enough.

You can tint the water to make the ice sculptures multi-colored. And as a result of such a simple experience, chemistry for 9-year-old children becomes an understandable and fascinating science. You can experiment by gluing ice cubes in the shape of a pyramid or diamond.

Experiment "Tornado"

This experiment does not require special materials, reagents or tools. The guys can do it in 10-15 minutes. For the experiment, let's stock up:

• plastic transparent bottle with a cap;
• water;
• dishwashing detergent;
• sparkles.

The bottle should be filled 2/3 with plain water. Then add 1-2 drops of dishwashing detergent to it. After 5-10 seconds, pour a couple of pinches of glitter into the bottle. Screw the cap tightly, turn the bottle upside down, holding it by the neck, and twist it clockwise. Then we stop and look at the resulting vortex. Before the “tornado” starts working, you will have to spin the bottle 3-4 times.

Why does a “tornado” appear in an ordinary bottle?

When a child makes circular movements, a whirlwind appears, similar to a tornado. The rotation of water around the center occurs due to the action of centrifugal force. The teacher tells the children about how scary tornadoes are in nature.

Such an experience is absolutely safe, but after it, chemistry for children becomes a truly fabulous science. To make the experiment more vivid, you can use a coloring agent, for example, potassium permanganate (potassium permanganate).

Experiment "Soap Bubbles"

Do you want to tell your children what fun chemistry is? Programs for children do not allow the teacher to pay due attention to experiments in lessons; there is simply no time for this. So, let's do this optionally.

For elementary school students, this experiment will bring a lot of positive emotions, and it can be done in a few minutes. We will need:

• liquid soap;
• jar;
• water;
• thin wire.

In a jar, mix one part liquid soap with six parts water. We bend the end of a small piece of wire into a ring, dip it into the soap mixture, carefully pull it out and blow out of the mold a beautiful soap bubble of our own making.

For this experiment, only wire that does not have a nylon layer is suitable. Otherwise, children will not be able to blow soap bubbles.

To make it more interesting for the children, you can add food coloring to the soap solution. You can arrange soap competitions between schoolchildren, then chemistry for children will become a real holiday. The teacher thus introduces the children to the concept of solutions, solubility and explains the reasons for the appearance of bubbles.

Entertaining experience “Water from plants”

To begin with, the teacher explains how important water is for cells in living organisms. It is with its help that nutrients are transported. The teacher notes that if there is not enough water in the body, all living things die.

For the experiment you will need:

• alcohol lamp;
• test tubes;
• green leaves;
• test tube holder;
• copper sulfate (2);
• beaker.

This experiment will require 1.5-2 hours, but as a result, chemistry for children will be a manifestation of a miracle, a symbol of magic.

Green leaves are placed in a test tube and secured in a holder. In the flame of an alcohol lamp, you need to heat the entire test tube 2-3 times, and then do this only with the part where the green leaves are located.

The glass should be placed so that the gaseous substances released in the test tube fall into it. As soon as heating is completed, add grains of white anhydrous copper sulfate to the drop of liquid obtained inside the glass. Gradually the white color disappears, and the copper sulfate becomes blue or dark blue.

This experience brings children into complete delight, because before their eyes the color of substances changes. At the end of the experiment, the teacher tells the children about such a property as hygroscopicity. It is due to its ability to absorb water vapor (moisture) that white copper sulfate changes its color to blue.

Experiment "Magic Wand"

This experiment is suitable for an introductory lesson in an elective course in chemistry. First you need to make a star-shaped blank and soak it in a solution of phenolphthalein (indicator).

During the experiment itself, the star attached to the “magic wand” is first immersed in an alkali solution (for example, in a solution of sodium hydroxide). Children see how in a matter of seconds its color changes and a bright crimson color appears. Next, the colored form is placed in an acid solution (for the experiment, using a hydrochloric acid solution would be optimal), and the crimson color disappears - the star becomes colorless again.

If the experiment is carried out for children, during the experiment the teacher tells a “chemical tale”. For example, the hero of a fairy tale could be an inquisitive mouse who wanted to find out why there are so many bright flowers in a magical land. For students in grades 8-9, the teacher introduces the concept of “indicator” and notes which indicators can determine the acidic environment, and which substances are needed to determine the alkaline environment of solutions.

"Genie in a Bottle" Experience

This experiment is demonstrated by the teacher himself, using a special fume hood. The experience is based on the specific properties of concentrated nitric acid. Unlike many acids, concentrated nitric acid is capable of chemical interaction with metals located after hydrogen (with the exception of platinum and gold).

You need to pour it into a test tube and add a piece of copper wire there. Under the hood, the test tube is heated, and the children observe the appearance of “red gin” vapors.

For students in grades 8-9, the teacher writes an equation for a chemical reaction and identifies signs of its occurrence (change in color, appearance of gas). This experiment is not suitable for demonstration outside the walls of a school chemistry laboratory. According to safety regulations, it involves the use of vapors of nitrogen oxide (“brown gas”) that pose a danger to children.

Home experiments

In order to whet the interest of schoolchildren in chemistry, you can offer a home experiment. For example, conduct an experiment on growing table salt crystals.

The child must prepare a saturated solution of table salt. Then place a thin twig in it, and as the water evaporates from the solution, crystals of table salt will “grow” on the twig.

The jar of solution should not be shaken or rotated. And when the crystals grow after 2 weeks, the stick must be very carefully removed from the solution and dried. And then, if desired, you can coat the product with colorless varnish.

Conclusion

There is no more interesting subject in the school curriculum than chemistry. But in order for children not to be afraid of this complex science, the teacher must devote sufficient time in his work to entertaining experiences and unusual experiments.

It is the practical skills that are formed during such work that will help stimulate interest in the subject. And in the lower grades, entertaining experiments are considered according to the Federal State Educational Standards as independent project and research activities.

CONTENT

Introduction.

Chapter 1. Chemical experiment in the process of teaching chemistry.

§ 1.1. Chemical experiment as a source of knowledge and a means of education.
.

Chapter 2. Issues of organizing a chemical experiment.

§ 2.1. Preparation of a chemical experiment by a teacher.
§ 2.2. Preparing students to perform a chemical experiment.
§ 2.3. Responsibilities of a laboratory assistant in preparing and conducting a chemical experiment.

Chapter 3. Chemical experiment technique.

§ 3.1. Demonstration technology.
§ 3.2. Performing laboratory experiments.
§ 3.3. Carrying out practical work.
§ 3.4. Solving experimental problems.
§ 3.5. Thought experiment.
§ 3.6. Chemical experiment in problem-based learning.
§ 3.7. Chemical experiment and technical teaching aids.

Chapter 4. Methodology for developing experimental skills and abilities.

§ 4.1. Classification of experimental skills and abilities.
§ 4.2. The role of observation in the process of developing experimental skills.

If you mentally trace the historical path of chemical science, you can be convinced that experiment plays a huge role in its development. All significant theoretical discoveries in chemistry are the result of a generalization of a large number of experimental facts. Knowledge of the nature of substances is achieved through experiment; it helps to reveal the relationships and interdependencies between them.
If experiment is so important in chemical science, then it plays an equally important role when teaching the basics of this science at school. The formation of ideas and concepts about substances and their transformations in a chemistry course, and on the basis of this, theoretical generalizations, is impossible without concrete observation of these substances and without a chemical experiment. At the same time, to explain the essence of observed chemical phenomena and processes occurring during a chemical experiment, students are required to have a deep knowledge of laws and theories. In addition, a chemical experiment plays an important role in developing skills for conducting experiments.
Consequently, only in close interaction between experiment and theory in the educational process can one achieve high quality of students’ knowledge in chemistry.
A chemical experiment should be considered as a process that includes two active parties - the teacher and the student. In this regard, a chemical experiment during training can be considered as a creative activity of a teacher aimed at “equipping” students with a certain system of knowledge, skills and abilities, and as a cognitive activity of students aimed at mastering a system of knowledge, skills and abilities. In the first case, the student acts as an object that is influenced, in the second - as a subject connecting both types of activities. Only in this way is a student able to penetrate into the essence of chemical phenomena and processes, master them at the level of general patterns, leading ideas and theories, and use the acquired knowledge for further knowledge of the subject of chemistry.
Issues of chemical experiments are considered in a number of works on methods of teaching chemistry. But in most cases, they pay attention to the technique of setting up experiments and much less often to the methods of using them in lessons. There are no special manuals specifically devoted to the methodology of a chemical experiment. Hence the main idea of ​​this manual is to show the methodology of a chemical experiment as an integral system and determine its significance in the process of teaching and upbringing in chemistry lessons and in extracurricular activities. From this position, the methodology is considered as an integral part of a chemical experiment, which will help improve the scientific and methodological training of chemistry teachers, and the implementation of its recommendations will help to activate students in the process of teaching chemistry.
The internal relationship between the activities of the teacher and students in the process of a chemical experiment will allow organizing the process of knowledge of chemistry not at the level of descriptive familiarization with phenomena and processes, but at the level of mastering their essence, explaining the cause-and-effect relationships between them from the standpoint of modern chemical science.
The methodological manual does not contain the development of all lessons on the topics, but provides only general recommendations that can be useful to the teacher when preparing and conducting a chemical experiment in the classroom, taking into account the content of the educational material and learning objectives.
A novice teacher in his work can use the recommendations from this manual to successfully master the technique of a chemical experiment. An experienced teacher, comparing his experience with the proposed methodology and showing a creative approach, can think through and improve the methodology for conducting a chemical experiment in his lessons.

Chapter I.
Chemical experiment
in the process of teaching chemistry

§ 1.1. Chemical experiment
as a source of knowledge and a means of education

When studying chemistry, chemical experiment plays an important role - an integral part of the educational process.
The experimental nature of chemistry is manifested primarily in the fact that every scientific concept must logically follow from the task at hand and be justified practically. Cognition begins with the sensation and perception of specific objects, phenomena, processes, facts and then proceeds to generalization and abstraction. A chemical concept is generalized knowledge about the essential features of chemical phenomena and processes that are formed on the basis of their perception. Their analysis makes it possible to find the essential features inherent in all of them and, on this basis, to establish chemical laws. Using various types of chemical experiments, the teacher teaches how to concretize theoretical knowledge and find the general in the individual, concrete. A chemical experiment helps students fill the chemical concepts they are learning with living, concrete content and see general patterns in individual facts.
A chemical experiment promotes the development of independence and increases interest in chemistry, because in the process of performing it, students become convinced not only of the practical significance of such work, but also have the opportunity to creatively apply their knowledge.
A chemical experiment develops students' thinking and mental activity; it can be considered as a criterion for the correctness of the results obtained and the conclusions drawn. Very often, an experiment becomes a source of formed ideas, without which productive mental activity cannot take place. In mental development, theory plays a leading role, but in unity with experiment and practice. The experience of chemistry teachers shows that one of the reasons for lagging behind in studies is the difficulty caused by the transition from visual images to abstract concepts. Systematically conducting experiments, during which children train in this skill, can help improve academic performance, in particular in chemistry. Students use the acquired skills and abilities not only for independent and active acquisition of knowledge while studying at a secondary educational institution, but also after graduation during self-education.
A chemical experiment is carried out in several stages:
first – justification for setting up the experiment,
second – planning and execution,
third – evaluation of the results obtained.
It is possible to carry out an experiment only based on previously acquired knowledge. The theoretical justification of experience contributes to its perception, which becomes more focused and active, and comprehension of its essence.
Conducting an experiment usually involves developing a hypothesis. Involving students in this work develops their thinking, forces them to apply existing knowledge to formulate a hypothesis, and as a result of testing it, the children gain new knowledge.
A chemical experiment opens up great opportunities both for creating and solving problem situations, and for testing the correctness of the hypothesis put forward.
Consequently, the experiment has a positive effect on the mental development of students, and the teacher has the opportunity to control the processes of thinking, learning and knowledge acquisition.
Chemistry programs make extensive use of chemistry experimentation—demonstrations, laboratory experiments, practical exercises, and experimental problems—throughout all years of study.
A chemical experiment can perform various didactic functions, be used in various forms and be combined with different methods and means of teaching. It is a system that uses the principle of gradually increasing the independence of students: from demonstrating phenomena through conducting frontal laboratory experiments under the guidance of a teacher to independent work when performing practical exercises and solving experimental problems.
Conducting demonstrations makes it possible to introduce students to various chemical phenomena and the connections between them, the generalization of which can form the basis of a law or theoretical conclusion; with the design and principle of operation of devices and installations; with the essence of the processes occurring in them, which can act as criteria for the correctness of conclusions.
A demonstration experiment is carried out for various purposes, for example, it can serve as the initial stage of mastering a theoretical position. Thus, when considering the conditions on which the degree of dissociation of electrolytes depends, the teacher suggests answering the question: “Does the degree of dissociation depend on the concentration of the solution?” An experience based on testing the electrical conductivity of concentrated and dilute solutions of acetic acid is demonstrated. Comparing the results of the experiment, students come to the conclusion that the degree of dissociation of the electrolyte depends on the concentration of the solution, and establish a pattern - with dilution of the solution, the degree of dissociation increases.
The demonstration experiment illustrates the correctness of the theoretical position stated by the teacher. For example, to prove that when some salts are heated, volatile acids are released, the teacher obtains nitric acid from nitrates and shows its specific properties or, speaking about the chemical properties of metals, shows experiments on the interaction of metals with non-metals and water. In this case, each time the teacher must clearly formulate the purpose of the experiment. His explanations help to analyze the results obtained, highlight the main thing, and establish connections between theoretical principles and experimental data illustrating them.
By performing laboratory experiments and practical work, students independently investigate chemical phenomena and laws and in practice become convinced of their validity, which contributes to the conscious acquisition of knowledge. Sometimes, when conducting these experiments, a creative approach is manifested - the application of knowledge in new conditions. This allows you to repeat, consolidate, deepen, expand and systematize knowledge from different sections of chemistry. In addition, schoolchildren develop experimental skills in handling reagents and equipment. All this helps to improve theoretical knowledge and polytechnic training of students.
By solving experimental problems, students improve their skills and abilities, learn to apply the acquired theoretical knowledge to solve specific problems.
You can also offer children experiments to perform at home. Home experiments and observations are simple experiments performed without teacher supervision. Conducting them teaches you to independently apply the acquired knowledge, skills and abilities.
Observation as a method of cognition is widely used when conducting chemical experiments. Students’ activities become purposeful and take on an active form, provided that the problem is clearly stated and a method for solving it is developed. For example, if the guys are observing the electrolysis of copper(II) sulfate, then the main thing is to monitor the change in color of the salt solution and the appearance of a red coating on one carbon electrode and gas bubbles near the other. Students interpret the results of observations taking into account their existing theoretical knowledge.
When monitoring the implementation of experiments (laboratory and practical classes), as well as during solving experimental problems, all analyzers function. With their help, children can determine the color, smell, taste, density and other properties of the objects under study, by comparing which they learn to identify essential features and learn their nature.
The experiment should become a necessary part of the lesson when studying specific issues. Students must know why to conduct an experiment, what theoretical position it confirms, and what question it will help answer. For example, when explaining the chemical properties of metals, the teacher brings up for discussion the question: “Do all metals interact with water?” After the teacher demonstrates the experiments, the children independently draw a conclusion: metals located in the voltage series to the right of hydrogen do not interact with water.
It is very important to analyze the results of experiments in order to obtain a clear answer to the question posed at the beginning of the experiment, to establish all the reasons and conditions that led to the receipt of these results. In addition, a properly organized experiment fosters conscious discipline, develops creative initiative, and respect for property.
The working environment in the laboratory and the exemplary order in it also have an educational effect on students and improve discipline. The laboratory must be constantly kept clean, there must be a strictly thought-out system for storing equipment and reagents: solids - in cabinets according to groups of the periodic table; solutions - by main classes of compounds or by cations or anions; organic substances - also by main classes of compounds or functional groups. Dishes and equipment are neatly arranged in cabinets.
Preliminary preparation of theoretical material for the upcoming practical work increases interest in the latter, which means that the children will be active and disciplined during the lesson. A meaningful understanding of the essence of the experiments, as well as careful execution of the completed work, have a positive effect on the behavior of students during the experiments.
It is necessary to ensure that all students complete practical work and obtain the desired results, so that they feel confident in their abilities and strive to overcome difficulties.
It is very important to provide differentiated assistance: carefully monitor the work of each person, note how he plans and organizes his work, how he masters the skills and techniques of conducting an experiment, whether he can observe, explain the essence of the phenomena occurring, and draw correct conclusions and generalizations. It is necessary that each student independently comprehend the material, use theoretical knowledge to explain ongoing phenomena and processes, draw conclusions and generalizations. When performing experiments, careful use of reagents and materials should be required, and the significance of their savings for the educational institution and the state should be explained.
Particular attention is paid to the technique of performing the work: how to dissolve substances, heat the solution in a test tube or flask, add indicator solutions, etc.
Safety instructions must be posted in a visible place. This teaches you to be organized and disciplined during classes.
The systematic use of experiments in chemistry lessons helps combat formalism in knowledge, develops the ability to observe facts and phenomena and explain their essence in the light of studied theories and laws; forms and improves experimental skills; instills the skills to plan your work and exercise self-control; fosters respect and love for work. This work contributes to general education, comprehensive personal development, and prepares for activities in modern production.

§ 1.2. Types of chemical experiment

Chemical experiment is important in studying chemistry. There are educational demonstration experiment, performed primarily by the teacher on a demonstration table, and student experiment– practical work, laboratory experiments and experimental tasks that students carry out at their workplaces. A unique type of experiment is a thought experiment.

Demonstration experiment is carried out mainly when presenting new material to create in schoolchildren specific ideas about substances, chemical phenomena and processes, and then to form chemical concepts. It allows you to make clear important conclusions or generalizations from the field of chemistry in a short period of time, teach you how to perform laboratory experiments and individual techniques and operations.
Students' attention is directed to performing the experiment and studying its results. They will not passively observe the conduct of experiments and perceive the material presented if the teacher, demonstrating the experiment, accompanies it with explanations. Thus, he focuses attention on experience and teaches him to observe the phenomenon in all its details. In this case, all the teacher’s techniques and actions are perceived not as magical manipulations, but as a necessity, without which it is almost impossible to complete the experiment. During demonstration experiments, compared to laboratory experiments, observations of phenomena take place in a more organized manner. But demonstrations do not develop the necessary experimental skills and abilities, and therefore must be supplemented by laboratory experiments, practical work and experimental tasks.

The demonstration experiment is carried out in the following cases:

it is impossible to provide the required amount of equipment at the disposal of students;

the experiment is complex and cannot be carried out by schoolchildren themselves;

students do not have the necessary equipment to conduct this experiment;

experiments with small amounts of substances or on a small scale do not give the desired result;

experiments are dangerous (working with alkali metals, using high voltage electric current, etc.);

It is necessary to increase the pace of work in the lesson.

Naturally, each demonstration experience has its own characteristics depending on the nature of the phenomenon being studied and the specific educational task. At the same time, the chemical demonstration experiment must meet the following requirements:

The pedagogical effectiveness of a demonstration experiment, its influence on knowledge and experimental skills depend on the experimental technique. This refers to a set of instruments and devices specially created and used in a demonstration experiment. The teacher should study the classroom equipment as a whole and each device separately, and practice demonstration techniques. The latter is a set of techniques for handling instruments and apparatus in the process of preparing and conducting demonstrations, which ensure their success and expressiveness. Demonstration methodology is a set of techniques that ensure the effectiveness of the demonstration and its best perception. The methodology and demonstration technique are closely related and can be called the technology of demonstration experiment.
When conducting demonstration experiments, a preliminary check of each experiment is very important in terms of technique, quality of reagents, good visibility by students of instruments and the phenomena occurring in them, and guarantees of safety. Sometimes it is advisable to display two devices on a demonstration table: one – assembled and ready for use, the other – disassembled, so that, using it, it is better to explain the structure of the device, for example, a Kipp apparatus, a refrigerator, etc.
You must always remember that any experiment that fails during demonstration undermines the authority of the teacher.

Laboratory experiments – a type of independent work that involves performing chemical experiments at any stage of the lesson for more productive learning of the material and obtaining specific, conscious and lasting knowledge. In addition, during laboratory experiments, experimental skills are improved, since students work mainly independently. Performing experiments does not take up the entire lesson, but only part of it.
Laboratory experiments are most often carried out to get acquainted with the physical and chemical properties of substances, as well as to clarify theoretical concepts or provisions, and less often to obtain new knowledge. The latter always contain a certain cognitive task that students must solve experimentally. This introduces an element of research that activates the mental activity of schoolchildren.
Laboratory experiments, unlike practical work, introduce a small number of facts. In addition, they do not fully capture the attention of students, like practical exercises, because after a short period of time independently completing the work (experience), students must again be ready to perceive the teacher’s explanation.
Laboratory experiments accompany the presentation of educational material by the teacher and, just like demonstrations, create in students visual representations of the properties of substances and chemical processes, and teach them to generalize observed phenomena. But unlike demonstration experiments, they also develop experimental skills. However, not every experiment can be carried out as a laboratory one (for example, ammonia synthesis, etc.). And not every laboratory experiment is more effective than a demonstration one - many laboratory experiments require more time, and the duration directly depends on the quality of the developed experimental skills. The purpose of laboratory experiments is to acquaint students with the specific phenomenon (substance) being studied as quickly as possible. The technique used is reduced to students performing 2-3 operations, which naturally limits the possibilities of developing practical skills.
The preparation of laboratory experiments should be carried out more carefully than demonstration ones. This is due to the fact that any negligence and omission can lead to a violation of the discipline of the entire class.
We must strive to ensure that each student performs laboratory work individually. As a last resort, you can allow no more than two people to have one set of equipment. This contributes to better organization and activity of children, as well as to the achievement of the goal of laboratory work.
After completing the experiments, they should be analyzed and a brief record of the work done should be made.

Practical work – a type of independent work when students perform chemical experiments in a specific lesson after studying a topic or section of a chemistry course. It helps to consolidate acquired knowledge and develop the ability to apply this knowledge, as well as the formation and improvement of experimental skills.
Practical work requires students to be more independent than laboratory experiments. This is due to the fact that the children are invited to get acquainted at home with the content of the work and the order of their implementation, and repeat theoretical material that is directly related to the work. The student performs practical work independently, which helps to increase discipline, composure and responsibility. And only in some cases, if there is a lack of equipment, can you be allowed to work in groups of two people, but preferably no more.
The role of the teacher in practical work is to monitor the correct execution of experiments and safety rules, the order on the work table, and the provision of individually differentiated assistance.
During practical work, students write down the results of experiments, and at the end of the lesson they draw appropriate conclusions and generalizations.

§ 1.2. Types of chemical experiment

(continuation)

Experimental tasks - a type of independent work that contains only a task, and students determine the choice of solution and conduct an experiment independently. This requires from them not only the active application of theoretical knowledge, but also the ability to perform relevant experiments. The main goals of experimental tasks are systematic exercises related to the application of knowledge in practice, as well as the development of experimental skills necessary for various studies.
In contrast to practical classes and laboratory experiments, experimental problems can be solved in every lesson throughout all years of chemistry education when studying and consolidating new material, monitoring students’ knowledge and at home. They can be done individually, in separate groups, or by all students at the same time. By solving experimental problems, schoolchildren not only improve previously acquired skills and abilities, but also learn to apply the acquired knowledge. This facilitates independent finding of a theoretical solution to the problem with mandatory experimental verification of the correctness of the result obtained.
Compared to computational problems, experimental problems are more cognitively valuable. This is explained by the fact that to solve such problems, a correct theoretical justification is not enough - you still need to carry out an experiment and explain its essence. Solving experimental problems allows the teacher to assess in a very short time how much the material has been mastered and how the student knows how to apply the acquired knowledge in practice. Discussion of the results makes it possible to detect errors or shortcomings in the solution, establish their causes, achieve their correction, provide students with differentiated assistance and outline ways to improve experimental skills.
According to their content, experimental tasks are divided into the following.

Tasks on observing physical and chemical phenomena and the ability to explain their essence. For example: “How can you determine from the physical and chemical properties of polyethylene and polystyrene which of the test tubes contains pieces of these plastics? Explain the essence of the observed phenomena."

Tasks on the implementation of the synthesis of substances and the ability to explain or anticipate the conditions for reactions. For example: “From the reagents available on the table - copper(II) oxide, water, copper(II) chloride, solutions of sodium hydroxide and hydrochloric acid - obtain copper(II) hydroxide in two ways. In each case, indicate the reaction conditions.”

Tasks on recognizing substances and the ability to explain their characteristic properties. For example: “Using characteristic reactions, determine which test tube contains glucose and starch. List their characteristic properties."

Tasks to confirm the qualitative composition of substances and the ability to characterize their properties. For example: “Use characteristic reactions to establish that this substance is aluminum chloride. List its characteristic chemical properties.”

Tasks to determine impurities in a given product and the ability to explain the reason for the chosen method of determining mixtures. For example: “Prove that copper sulfate contains sodium chloride impurities. Explain why the method you have chosen to determine the impurity is the most rational.”

Tasks on isolating a substance in its pure form from a mixture and the ability to explain the reason for the chosen method of separating mixtures. For example: “Isolate table salt in its pure form from a mixture containing iron(III) hydroxide and pieces of polyethylene. Explain why the method you chose to separate substances is correct.”

Tasks to consolidate the classification of substances and the ability to define them. For example: “Prove that aminoacetic acid is an amino acid. Define this class of substances."

Tasks on carrying out characteristic reactions and the ability to explain their typical properties. For example: “Identify glucose using characteristic reactions. List its typical chemical properties."

Tasks on preparing solutions of substances with different mass fractions and the ability to explain their preparation. For example: “Prepare 300 g of sodium bicarbonate solution, the mass fraction of which is 0.03, or 3%. Explain why you should first dissolve a substance and then add solvent to a certain mark. Why can’t you do it the other way around?”

Combined tasks that require in-depth knowledge and strong skills to perform.

Experimental tasks distinguish quality And computational and experimental. Qualitative problems are solved empirically; they lack quantitative data and, therefore, mathematical calculations, for example: “Prove experimentally the presence of sulfate ion in iron(III) sulfate.” To solve computational and experimental problems, in addition to setting up the experiment, it is necessary to process certain experimentally obtained data. It is proposed, for example, to obtain a precipitate of iron(III) hydroxide and, based on the resulting mass of the precipitate, calculate the mass of the solution for its preparation with a mass fraction of potassium hydroxide of 0.1 (10%).
The highest form of computational and experimental problems is computational-experimental, which combines the best qualities of both problems.

Thought experiment as a method of activating students’ cognitive activity, it has been unfairly forgotten, and chemistry teachers practically do not use it. This is most likely due to the lack of information about it in the numerous and varied methodological literature on chemistry and in the training of future chemistry teachers at universities. As a result, it turned out that the thought experiment, which contains great opportunities for developing students’ abstract thinking, does not find its proper application in the practice of teaching chemistry.
This situation could be to some extent justified and tolerable when a real chemical experiment was carried out constantly throughout all the years of studying chemistry at school. Currently, as a result of the current unfavorable social conditions, when a real chemical experiment is very expensive, and many reagents, equipment and accessories are missing and it is used less and less, or even not carried out at all, the question arises about the need to more widely use thought experiments as an alternative real.
A thought experiment costs nothing from a financial point of view; all it takes is a student's head to think. Since the thought experiment is carried out theoretically, it requires very little time. During this short period, active mental activity occurs: the goal of the experiment is set, a problem is created, a hypothesis is put forward, and ways to find and solve the problem are determined. In the absence of reagents and equipment, students theoretically discuss the progress of the experiment and its results and draw conclusions.
The role of the teacher when conducting a thought experiment is very important. He carefully monitors the correctness of the students’ reasoning and acts as an arbiter, assessing the possibility of implementing the student’s proposed way of completing the experiment and obtaining the final result.
In cases where the chemistry classroom has everything necessary to conduct an experiment, the students test their theoretical assumptions practically.
Thus, a thought experiment can be carried out in its pure form, that is, without experiments, and in close unity with a real experiment. In both cases, a thought experiment activates the cognitive activity of students and in every possible way deserves to be in the collection of methods that the teacher uses in his work.

Chapter 2.
Organizational issues
chemical experiment

The quality and effectiveness of a chemical experiment depend on the preparation and organization of it by the teacher, the preparedness of students and the assistance of a laboratory assistant.

§ 2.1.
Chemical preparation
experiment by teacher

The need for the teacher to prepare an experiment is determined by the educational tasks that are presented to the experiment by the content of the subject of chemistry and the methodology of its teaching.
The effectiveness of chemistry teaching is closely related to the overall planning of educational material. The main tasks that are solved during the planning process are optimizing the educational process, determining the volume of educational material, selecting tasks for the lesson and for home; allocating time to conduct laboratory experiments and practical classes, solving experimental and computational problems; control of knowledge, skills and abilities of students; consolidation and repetition of material.
A chemistry teacher must be able to plan an experiment on the entire topic and for a specific lesson, apply it methodically correctly, select experimental options, guide the cognitive activity of students, analyze and evaluate their own activities during demonstrations and the activities of students when they independently perform experimental work.
A chemical experiment is planned. To do this, at the beginning of the academic year, in a long-term plan, in accordance with the curriculum, the sequence of demonstrations, laboratory experiments, practical exercises and solving experimental problems on topics and their connection with theoretical classes is established; a list of experimental skills and abilities that students must acquire, and didactic means to achieve their goals are determined; extracurricular types of chemical experiments are established that have a professional orientation and significance for extracurricular activities.
Before starting to study the topic, a thorough and detailed analysis of the educational material is carried out to clearly determine, firstly, the amount of knowledge that the teacher himself should possess, and, secondly, the types of experiment that allow the best possible formation and improvement of skills in each lesson when studying this topic.
Promising And thematic planning together is necessary for the most rational and timely preparation for these classes.
Knowing in advance the timing of the experiment, the teacher has the opportunity to prepare equipment, teaching aids, etc. for lessons in advance.
Preparation for a lesson depends on the type of lesson and the didactic goal set. First, the teacher clarifies the educational objectives of the lesson and thinks over the methodology for its implementation. In order for a chemical experiment to provide solid and deep knowledge, it is necessary to foresee what experimental skills and abilities will be acquired by students, with the help of what techniques can be used to achieve their understanding of the observed chemical transformations. The teacher is recommended to review the relevant methodological literature, outline questions that will help identify students’ theoretical knowledge on the topic, and highlight points that should be focused on, since they contribute to the acquisition of skills and abilities and facilitate the perception of educational material in the future.
The teacher needs to think about at what stage of the lesson, in what sequence, with what reagents and instruments to conduct the experiments, determine their place during the lesson depending on the significance of the tasks, as well as the form for recording the results obtained (figure, table, reaction equation, etc.). d.).
Before the lesson, it is very important to rehearse the technique for performing each demonstration experiment, check the availability and quality of reagents, and also make sure that the operation of the device and the phenomena occurring are clear, since problems discovered during the lesson affect not only the students’ discipline, but also achieving the set goal. If necessary, reagents should be replaced, instruments adjusted, or other suitable equipment used.
For example, to burn ethylene, acetylene and other gases, it is not necessary to have a straight gas outlet pipe with an extended end. You can use a gas outlet tube at a right angle, keeping in mind that the flow of gases in this case will be sufficient to maintain uniform combustion of gases. Lime water, which becomes unusable due to improper or long-term storage, can be completely replaced with barite water (Ba(OH) 2 solution), the properties of which do not undergo any changes even after long-term storage. If for some reason there is no phenolphthalein in the office, then it can be replaced with purgen (a laxative), which contains phenolphthalein and sugar. Purgen acts similarly to pure phenolphthalein. Instead of silver nitrate, you can use lapis, etc.
In other cases, missing reagents can be obtained in various ways from substances available in the office. It is recommended to involve students for this type of work. This helps the teacher and develops students’ interest in a more in-depth study of chemistry.
When preparing for an experiment, it is also recommended to use cards on which all the necessary data about the experiment is entered: the names of devices, reagents, and accessories are marked on one side, and the drawing of the device and installation diagram are marked on the other. To better preserve and extend the life of the cards, you can place them in a cellophane envelope or print them on two pages of notebook paper and then stick them on cardboard or thick paper.
These cards are intended for a laboratory assistant preparing an experiment (demonstrations, laboratory experiments, practical exercises and experimental problems), and the teacher checks his work.
In some cases, it is advisable to have two identical devices, one of which, disassembled, is used to explain its structure, and the other, assembled, is used to demonstrate it in action.
It is also necessary to show students the physical state of the substances from which their solutions are prepared. This applies to the most commonly used substances such as sodium hydroxide, calcium hydroxide, indicators, barium chloride, etc. This repeated comparison allows students to remember that all bases and salts are solids under normal conditions. But in everyday practice they are more often used in the form of solutions of a certain concentration.
The devices that were shown during the demonstration are not disassembled, but are used when questioning students in subsequent lessons.
The study of the physical properties of simple substances and the most important compounds of elements presupposes familiarity with their most important characteristics. To do this, the teacher needs to have sets of handouts for each table. Samples of substances with names and indicated composition are placed in cardboard boxes, they are distributed during the lesson, when it is necessary to familiarize students with them, and immediately after that they are removed. Liquid or solid substances in the form of crystals (or powder), respectively, are poured or poured into jars, flasks or test tubes and in this form are given to students to become familiar with their external characteristics.
For surveys on topics such as “Nitrogen and Phosphorus”, “Carbon and Silicon”, “Metals” and others, it is good to have thematic collections of samples of substances and minerals without their names inscribed.
It is necessary to familiarize students in advance with the list of names of practical work that they will perform in subsequent lessons, so that the children can prepare in advance. In the lesson preceding the practical lesson, the teacher informs the topic, purpose and content of the work, and indicates pages in the textbook for repetition of theoretical material. Students at home carefully read the instructions for the lesson, think through the progress of the work and report on its implementation. In case of any difficulties, it is recommended to refer to the text of the textbook or notes in the notebook.
Before completing the work, the teacher invites students to carefully read its contents again and repeat the progress.
During the conversation, the teacher first checks the degree of preparation for the practical lesson: how theoretically the experiment makes sense. He clarifies the purpose and content of the work to be done, the order in which its individual elements are performed, safety precautions, and the form and content of the report.
Students are given the opportunity to carry out experiments on their own, and the teacher only observes the progress of the work and intervenes if the student makes a serious mistake or fails to complete the task. When walking around students (primarily low-achieving students) in the classroom, the teacher gives the necessary instructions. But help should be provided in such a form that students learn to overcome difficulties on their own, analyze their mistakes, correct them, and show initiative.
Written reports drawn up as the work progresses must contain a drawing of the device, recordings of observations, explanations of the results, answers to questions, instructions, and conclusions.
If the work is small in volume or students have a stable skill in preparing a report, then it is necessary to require the preparation of a report in this lesson. In cases where students do not have time to complete a progress report, they may be allowed to submit rough notes. The teacher checks and signs these notes and returns them to the students for final registration at home during the next lesson. Writing a report at home should be permitted in exceptional cases and only for selected students.

Sketching of instruments or equipment is necessary when the drawing reveals the feature or essence of a given experience and also facilitates recording. For example, when producing ammonia, the opening of the gas outlet tube should be directed upward (Fig. 1). This makes it possible to more conveniently and completely collect ammonia in test tubes, since its relative density is almost half that of air. When producing carbon(IV) monoxide, the opening of the gas outlet tube is directed downward, since its relative density is 1.5 times greater than air (Fig. 2). This position of the tube allows you to collect more carbon monoxide (IV) and better study its properties. From these examples it is clear that in both cases there is a close relationship between the physical properties of gases and the peculiarities of their production, which should be displayed in the report using a figure.
Summing up the results of practical exercises should be carried out in the next lesson. The best works are read out (in part or in full), typical errors are analyzed, the best drawings are shown through an epidiascope, some students are interviewed orally, etc.
A chemistry teacher in secondary schools is faced with the need to independently compile the content of experimental problems on the topics of a chemistry course, and in evening secondary schools also with production content. This is due to the fact that there are no such problems in textbooks, and also because workers of various professions are trained in evening secondary schools.
When selecting experimental tasks, the teacher must comply with the following requirements:

tasks must cover all educational material for the chemistry course;

the content of the tasks should take into account the different levels of students’ preparation and the individual characteristics of their development;

tasks should contribute not only to improving the quality of knowledge in chemistry and improving experimental skills, but also to improving the professional training of workers;

the time allocated for solving problems must be strictly limited;

the conditions of the tasks must be clearly formulated.

Exam papers in chemistry must include laboratory experiments and experimental tasks, the purpose of which is to test the presence of experimental skills of students.
Examples of experiments and tasks for each ticket are prepared by the teacher.
The effectiveness of conducting lessons with a chemical experiment largely depends on how modern requirements of the scientific organization of work (SLO), ergonomics, safety precautions and aesthetics are taken into account when equipping the teacher’s workplace.
The chemistry teacher, who is also the head of the chemistry laboratory, is responsible for organizing all the work to equip his office with new equipment and devices. Under his leadership, a list of necessary equipment and inventory is compiled for the current and subsequent years. To troubleshoot equipment and produce new manuals in the office, it is advisable to create a circle and involve students in participating in its work.

§ 2.2.
Preparing students to perform
chemical experiment

Correct and quick implementation of practical work in the classroom depends to a large extent on the good preparation of students and the organization of classes.
Preparing students involves doing homework before the practical lesson, namely: repeating the relevant theoretical material from the textbook, becoming familiar with the content of the experimental work in order to know what practical skills will be necessary to complete it.
For example, to complete the practical work “Preparation of ethylene and experiments with it,” students repeat material about the structure of the molecule, production, physical and chemical properties of ethylene, paying special attention to the dependence of these properties on the structure of the molecule; get acquainted with the picture, which shows a device for producing ethylene; remember how to properly assemble, check for leaks and strengthen the device for producing gases; repeat what precautions must be taken when working with starting substances.
To maintain correct posture and good vision, students must be provided with comfortable workplaces in accordance with the requirements of the scientific organization of labor (SLO) and ergonomics. The equipment must be made taking into account the anthropometric characteristics of students and the nature of work activity. Workstations are equipped with the necessary equipment and reagents and are assigned to students for a certain period of time. They are required to maintain order on the table while doing work and after it is completed.
During the experiment, students, following the instructions, carefully observe the signs and conditions of the reactions and record all the changes that occur in their notebooks.
Reports on practical exercises are prepared in separate notebooks. Reports are compiled approximately according to the following scheme: name and date of work; list of instruments and equipment; description of the progress of work (assembly of the device, reagents, observations, explanation of results, etc.); diagrams and drawings reflecting the essence of the observed phenomena; generalization and conclusions; short answers to the questions posed in the assignment.
It is advisable that the report be submitted on the day of the practical work. Writing a report teaches students to analyze their actions, make generalizations and conclusions.
After the practical lesson, the equipment is removed, which is controlled by the laboratory assistant: each student collects from the table and puts on a tray (or cuvette) all the individual objects and reagents and takes them to the laboratory room. The attendants check the cleanliness of student tables. All this is done quickly and does not interfere with the next lesson. Then the laboratory assistant and students disassemble the trays, wash test tubes and other utensils, and place laboratory supplies and reagents in their permanent places (in cabinets and on shelves).
Conducting experiments in practical classes requires composure, precision and accuracy. If you are poorly prepared for the work or perform it carelessly, the experiments may not work out. During the work itself, students become convinced that successful implementation of experiments is possible only with a deep understanding of the material studied and the ability to apply theoretical knowledge in practice.
As a rule, in practical classes, students repeat experiments that the teacher has already demonstrated when studying a given topic. But, observing these experiments from a distance, the guys cannot always understand the details. After theoretical training, they have the opportunity to repeat the experiments on their own, delve into all the details of the experiments and explain their essence. This creates interest in the work, and knowledge, supported by practical work, becomes more durable and effective.
As they acquire knowledge and experimental skills, children should be given more independence in conducting chemical experiments in practical classes. You can offer to independently analyze the experimental technique, draw up a work plan, conduct observations and explain the results obtained. This method of performing experiments is close to solving experimental problems, which in a practical lesson should also be preceded by careful home preparation. The course of solving problems is thought through, a plan for conducting relevant experiments is developed, and a list of necessary reagents, materials, utensils and accessories is compiled. This allows students to come to the laboratory and immediately begin performing the experiment. Experimental tasks are performed without instructions, so they require significantly more independence from students.
Not all students finish practical work at the same time, which is understandable. Everyone has their own skills, individual characteristics, their own level of preparedness, and hence the unequal pace of work. Some do not meet the allotted time, others finish work ahead of schedule. For those who cope with the task earlier, you can offer task cards with the content of new experiences. This helps maintain a working environment in the classroom and stimulates students' thinking.
In contrast to practical classes, laboratory experiments are performed by all students under the guidance of a teacher; this contributes to a conscious and specific understanding of the new educational material. Little time is allocated for them, so attention, diligence and discipline are required from students. Experiments are carried out according to the teacher’s verbal instructions or according to task cards, the content of which can be projected using an epidiascope or overhead projector onto the screen.
A special stand should indicate what general skills and abilities students should master while studying a course in inorganic and organic chemistry. Using individual examples, you can demonstrate the importance of any specific skill acquired.
For example, what you need to know when working with a gas burner. Natural gas is poisonous, so releasing it indoors is unacceptable; when the burner is not in use, the taps must be closed; the greatest amount of heat is released when a non-luminous flame is formed. When lighting a gas burner, you should adhere to the following order: connect the burner with a rubber tube to the tap; close the air access using a disk or clip; ignite the gas a few seconds after it starts; adjust the air supply so that the flame becomes non-luminous; during operation, make sure that there is no “breakthrough” of the flame - the gas ignites in the lower part of the tube and burns inside it, and not in the upper part of the tube; If a “slip” is detected, the burner must be extinguished immediately, allowed to cool and re-ignited with the vent closed.
It is recommended to indicate literature on this topic at the same stand.
It is very good to keep records in the classroom of the development of experimental skills and abilities by year of study, which serves as a kind of control and self-control. Accounting consists of a list of developed and practiced skills and abilities of each student in inorganic and organic chemistry.
During the exam, the student occupies one of five tables, which are equipped specifically for performing laboratory experiments and solving experimental problems. At this table, he prepares answers to the theoretical questions on the ticket and plans the sequence of the experiment. First, the student writes down the equation of a chemical reaction, then makes a list of the reagents and equipment that he intends to use in a given experiment or experimental task, and also, if necessary, makes a drawing or diagram. Only after the teacher has checked the notes does the student begin to perform the experiment.
When assessing the performance of laboratory experiments and solving experimental problems, they take into account the ability to test devices for leaks, assemble them and strengthen them in a laboratory stand, use reagents and equipment, use reagents economically, consistently perform operations when recognizing or obtaining substances, observe safety precautions, etc.
Students who already have well-developed work skills should be involved in the work of equipping the classroom. They can produce the missing tables on the production of substances, installation diagrams, drawings of devices, operating installations and instruments, collections, and also take part in collecting jars and bottles. Parents and children who graduated from this school can provide great assistance in this work.

§ 3.3. Carrying out practical work

The approximate timing of practical work is determined according to the thematic plan.
In the lesson plan, the teacher outlines how he will observe and control the work of the entire class and individual students, what technical and theoretical difficulties the children may encounter when performing experiments, and what differentiated assistance they need to provide to successfully complete and complete the work.
The plan also records the possible replacement of reagents or equipment, changes in the content of any experiment, lists questions on which students’ theoretical preparedness for the lesson will be tested, and also provides instructions on the technique of performing experiments.
Practical skills are successfully developed if schoolchildren already have sufficient theoretical knowledge. In this case, individual operations are performed more meaningfully and strong skills are acquired. Therefore, the teacher first of all needs to check the theoretical preparation of students for the upcoming work. For this purpose, questions are proposed with the help of which the teacher controls the strength and depth of knowledge and at the same time activates mental activity.
Questions, naturally, should follow from the content of the practical work itself. If any changes in the work are planned, this will also be announced at the very beginning of the lesson. Then the teacher answers questions that arose while preparing for the lesson at home, explains and shows the techniques that will be used for the first time. Less time is devoted to explaining the techniques for carrying out already known operations and techniques, which the children are once again familiar with according to the instructions for practical work. But much more time is devoted to monitoring the implementation of these operations during work.
After this, students carry out experiments, and the teacher monitors the quality of their implementation and, if there are difficulties, provides differentiated assistance. If an error is discovered, there is no need to rush to correct it; the student must be given the opportunity to think and do it on their own.
If the chemistry laboratory is equipped with everything necessary for an experiment, then during practical classes each student performs experiments independently. If such conditions are absent, then the practical work is performed by two students in turn: each conducts approximately half of the intended experiments. But even if schoolchildren perform experiments in pairs, each student submits a report on the work done separately. This forces them to delve into the essence of the work being carried out by their comrade, observe, and draw conclusions.
When conducting experiments, you should ensure that each student is an active performer, and not a passive contemplator. Only under this condition are experimental skills consolidated and improved.
The teacher records his observations in a notebook where the names of students, elements of operations, as well as skills and abilities that are acquired or improved in this lesson are recorded. Some comments are briefly recorded in the “Notes” column.
For example, during practical work on the topic “Recognition of polymeric materials - plastics, chemical fibers,” the teacher monitors the correct development of the following experimental skills:

light and extinguish burners (alcohol lamps);

identify plastics and fibers by appearance;

determine the density of plastic;

identify plastics and fibers by their combustion patterns;

use crucible tongs;

work with lookup tables.

As the students complete their experiments, they record their results in notebooks and then compile a written report. In any form of report, it should contain a brief record of observations, their explanation and conclusions. Students think through the order of performing experiments at home in preparation for class, so they spend significantly less time on writing a report during practical work. You should not transfer the preparation of reports to home, as this discourages students in class. In addition, the results obtained during observation are quickly forgotten, which leads to cheating.
Student laboratory assistants provide great assistance in preparing practical work. They help display and put away all the sets on trays. These students can be called upon to observe the work of their comrades and help them when difficulties arise. To ensure success, it is advisable to give these students the opportunity to complete practical work in advance and provide them with a list of questions on which they should conduct observations.
Students' performance in practical work is assessed on the basis of a written report and observation results. Such criteria could be:

error-free and accurate execution of experiments;

correct recording of explanations, conclusions and reaction equations;

skillful handling of reagents and equipment;

quality of report design;

compliance with safety precautions and discipline during classes.

Typical mistakes made when performing experiments are discussed in the next lesson. Individual students are invited to carry out some practical experiments at the demonstration table. The whole class participates in discussing their results.
Practical work carried out according to textbook instructions limits the independence of students, since the content of these works involves mainly executive activity. Issues related to the development of students' thinking should be resolved on the basis of their increasing independence in carrying out this work. A lot can be done in this direction without changing the topics and the amount of practical work provided for in the program.
Let's take a practical example as an example. on the topic “Determination of mineral fertilizers”, the implementation of which requires great activity and independence.

Research objectives.
1. Using characteristic reactions, determine ammonium nitrate, sodium nitrate and potassium salt located under numbers in test tubes (in bags).
2. Prove that the composition of ammonium nitrate includes ammonium ions and nitrate ions of sodium nitrate - sodium ions Na + and nitrate ions, potassium salt - potassium ions K + and
chloride ions Cl – .

Research plan.
1. Consider the appearance of the fertilizer.
2. Check the solubility of fertilizers in water.
3. Pour a concentrated solution of sulfuric acid into test tubes with solid fertilizers, lower the pieces of copper ( for what purpose?) and warm up slightly ( Why?).
4. Pour into test tubes with fertilizer solutions:
a) a solution of barium chloride and acetic acid ( For what?);
b) alkali solution ( for what purpose?) and heat ( Why?);
c) silver nitrate solution ( For what?).
5. Apply fertilizer crystals ( How?) into the flame of a burner or alcohol lamp ( for what purpose?).
6. Carefully observe the phenomena occurring.
7. Write down reaction equations.
8. Note the characteristic coloring of the flame of a burner or alcohol lamp when applying fertilizers to it.
9. Draw appropriate conclusions.

Questions to check.
1. How to determine the ions Na + , K + , , , Cl – ?
2. Is it possible to distinguish Na + and ions by the color of the flame? Why? How should they be defined?
3. For what purpose is concentrated sulfuric acid added to fertilizers simultaneously with pieces of copper? Give a reasoned answer.
4. Why is acetic acid added along with barium chloride?
5. How can we explain that many fertilizers turn the flame yellow?
6. How can we explain the unequal degree of heating of fertilizers with concentrated sulfuric acid and copper, as well as with sodium hydroxide solution?
7. How else can you determine the nitrate ion in alkali metal salts?

Determining the objectives of the experiment and drawing up a research plan helps students focus on the most important thing during experiments. With the help of test questions for practical work, they find out the degree of their understanding of the essence of phenomena and processes, as well as the ability to apply the acquired knowledge in new situations.
The teacher can, by analogy, independently compose the content of other practical works.
At the final lessons, practical work of new content is not carried out. However, it is advisable to devote the last two lessons only to a chemical experiment. On one of them, students obtain gases known to them (oxygen, ammonia, carbon monoxide (IV), hydrogen, ethylene, etc.) and prove their presence, on the other, they solve experimental problems to recognize inorganic and organic substances. Despite the fact that students have performed these experiments before, they are repeated on a new and higher quality basis. This is expressed not only in the ability to quickly and independently conduct experiments, but also in greater demands on evaluating the results of work.
The quality and strength of acquired skills and abilities depend on the frequency of their use in practical work. The fact that some skills and abilities are used during training only once or twice, and then with a long break, does not exclude the fact that students, if necessary, will apply and improve them in their work activities.

Chapter 4. Methodology for developing experimental skills and abilities

§ 4.1. Classification of experimental skills and abilities

The unity of theory and practice, as is known, most contributes to the solid assimilation of educational material, therefore theoretical knowledge in chemistry should be based on experiment, and a chemical experiment should involve the application of theoretical knowledge. In the learning process, both of these links must be in close relationship, and neither of them can be belittled or exalted.
Experimental skills and abilities must be developed systematically by performing laboratory experiments, conducting practical classes and solving experimental problems. The success of this work largely depends on the teacher’s knowledge of the structure and content of experimental skills, as well as on the conditions for the effective use of various types of educational chemical experiments.
According to the form of student activity, the experimental skills that are formed in the process of teaching chemistry can be divided into five groups:
organizational;
technical;
measuring;
intellectual;
design.

Based on the chemistry curriculum, it is possible to establish the content of skills and abilities for each of these groups.

Organizational skills:
1) planning the experiment;
2) selection of reagents and equipment;
3) rational use of time, means, methods and techniques in the process of performing work;
4) exercising self-control;
5) keeping the workplace clean and tidy;
6) independence in work.

Technical skills:
1) handling of reagents and equipment;
2) assembly of devices and installations from finished parts and assemblies;
3) performing chemical operations;
4) compliance with labor safety rules.

Measuring skills:
1) measuring volumes of liquids and gases;
2) weighing;
3) measurements of temperature and density of liquids;
4) processing of measurement results.

Intellectual skills:
1) clarifying the purpose and defining the objectives of the experiment;
2) putting forward a hypothesis;
3) use of existing knowledge;
4) description of observed phenomena and processes;
5) analysis of the experimental results;
6) establishing cause-and-effect relationships;
7) generalization and conclusions.

Design skills:
1) repair of equipment, instruments and installations;
2) improvement of equipment, instruments and installations;
3) manufacture of equipment, instruments and installations;
4) graphic design (in the form of drawings and diagrams) of equipment, instruments and installations.
Dividing skills into five separate groups cannot yet solve the problem of students successfully mastering them. Some children will master organizational skills and abilities well and quickly, others - intellectual, others - technical, etc. Therefore, in accordance with the chemistry program, it is necessary to determine lists of skills that students must master depending on their level of training and individual characteristics. In this regard, all experimental skills can be divided into three levels.
TO first level These include the typical skills and abilities necessary for all students to master the content of the chemistry curriculum. At this level, students perform practical exercises or laboratory experiments according to instructions and still need supervision and assistance from the teacher. As they master the required skills, it is necessary to require students to demonstrate increasing independence when performing experiments.
Second level involves the acquisition by students of such skills and abilities that would allow them to perform a chemical experiment without detailed instructions, under changed conditions, to use algorithmic instructions for experiments, and to demonstrate independence in their work. At the same time, such students occasionally need the supervision and help of a teacher.
Third level constitute skills and abilities characteristic of students who show a deep interest in chemistry, independence and a creative approach when performing a chemical experiment. These students do not need the teacher’s control and assistance.
Below is an approximate list of experimental skills for each level by group.

Organizational skills

First level:
1) drawing up an experimental plan according to the instructions;
2) determination of the list of reagents and equipment according to the instructions;
3) preparation of a report form according to instructions;
4) performing the experiment at a given time, using familiar means, methods and techniques in work;
5) carrying out self-control according to instructions;
6) knowledge of the requirements for written documentation of experimental results;
7) the lack, as a rule, of cleanliness and order in the workplace;
8) the need for systematic control and assistance in work from the teacher.
Second level:
1) drawing up an experimental plan without detailed instructions;
2) determination of the list of reagents and equipment without detailed instructions;
3) preparing a report form without detailed instructions;
4) rational use of time, means, methods and techniques in the course of performing work;
5) carrying out self-control without instructions;
6) written documentation of the results of the experiment using reference literature, with a drawing or diagram;
7) keeping the workplace clean and tidy;
8) occasional need for control and assistance in work from the teacher.
Third level:
1) independent planning of the experiment and its theoretical justification;
2) independent determination of the list of reagents and equipment;
3) making changes to the report form;
4) economical use of time and selection of the most effective means, methods and techniques in the process of performing work;
5) increasing the number of self-control criteria;
6) written documentation of the experiment results using reference and scientific literature, drawings;
7) keeping the workplace clean and tidy throughout the experiment;
8) independent execution of the experiment.

Technical skills

Second level:
1) proper handling of various reagents and equipment;
2) assembly of devices and installations from finished parts according to a drawing or diagram without detailed instructions;
3) establishing the order of operations without detailed instructions;
4) constant compliance with all labor safety rules.
Third level:
1) correct handling of various reagents and equipment and replacement of one with another;
2) assembly of devices and installations from finished parts according to the drawing;
3) independently drawing up the order of all operations and performing them during the experiment;
4) strict compliance with all labor safety rules.

Measuring skills

First level:
1) work with measuring instruments in accordance with the instructions;
2) knowledge and use of measurement methods according to instructions;
3) processing of measurement results according to instructions.
Second level:
1) working with measuring instruments without detailed instructions;
2) knowledge and use of measurement methods without detailed instructions;
3) processing of measurement results without detailed instructions.
Third level:
1) independent work with various measuring instruments;
2) use of various measurement methods;
3) involvement of computer equipment, tables, reference literature, etc. in the processing of measurement results.

Intellectual skills

First level:
1) clarifying the purpose and defining the objectives of the experiment according to the instructions;
2) putting forward an experiment hypothesis with the help of a teacher;
3) selection and use of theoretical knowledge as directed by the teacher;
4) observation and identification of characteristic signs of phenomena and processes according to instructions;
5) comparison, analysis, establishment of cause-and-effect relationships, generalization of the results obtained and formulation of conclusions under the guidance of a teacher.
Second level:
1) defining the purpose and objectives of the experiment without detailed instructions;
2) putting forward a hypothesis and determining the content of the experiment with minor help from the teacher;
3) use of theoretical knowledge by analogy;
4) observation and establishment of characteristic signs of phenomena and processes without detailed instructions;
5) comparison, analysis, establishment of cause-and-effect relationships, generalization of the results obtained and formulation of conclusions with minor participation of the teacher.
Third level:
1) independent determination of the purpose and objectives of the experiment;
2) independently putting forward a hypothesis and drawing up an algorithm for conducting an experiment;
3) independent use of theoretical knowledge in new conditions;
4) independent observation and identification of characteristic signs of phenomena and processes;
5) independent implementation of synthesis, analysis, establishment of cause-and-effect relationships, generalizations, formulation and comparison of conclusions with the purpose and objectives of the experiment.

Design skills

First level:
1) correcting simple problems in equipment, devices and installations according to instructions under the supervision of a teacher;
2) use of ready-made equipment, instruments and installations;
3) production of simple equipment, instruments and installations under the guidance of a teacher;
4) image of equipment, instruments and installations in the form of a drawing.
Second level:
1) repair of equipment, instruments and installations as directed by the teacher;
2) making some changes to the design of equipment, instruments and installations;
3) production of simple equipment, instruments and installations according to instructions;
4) image of equipment, instruments and installations in the form of a diagram.
Third level:
1) independent repair of equipment, devices and installations;
2) improvement of the design of equipment, instruments and installations;
3) production of devices according to drawings;
4) image of equipment, instruments and installations in the form of a drawing.

Students’ work performance at the first level can be assessed with a mark of “3”, at the second – with a mark of “4” and at the third level – with a mark of “5”.
Let's consider the formation of experimental skills using the proposed levels of mastery when performed by 8th grade students practical lesson “Production and properties of oxygen”.

The first group of students completes a not very difficult task (first level).

Option 1
Job objectives:
1) obtain oxygen by decomposing potassium permanganate when heated and collect it by displacing air;
2) prove that the resulting gas is oxygen;
3) check the combustion of coal in oxygen.
Work plan:
1) assemble a device for producing oxygen;
2) check it for leaks (how?);
3) insert a ball of cotton wool into the device (for what?);
4) prepare test tubes, jars or flasks to fill them with oxygen;
5) carefully heat the entire length of the test tube (why?) containing potassium permanganate, and then heat the place where the reagent is located;
6) monitor the beginning of oxygen release (by what sign?);
7) collect the released gas;
8) test the resulting gas in a test tube (how?);
9) study the combustion of coal in air and oxygen;
10) pour a little lime or barite water into the jar or flask in which the coal was burned (what is observed?);
11) draw up an equation for the chemical reaction of coal combustion and draw the appropriate conclusions;
12) draw up a report on the work done.
Questions for self-control.
1) How to check the tightness of a device for producing gases?
2) What role does cotton wool play in a device for producing oxygen from potassium permanganate?
3) How to determine the beginning of oxygen release?
4) How can you recognize oxygen among other gases?
5) How can we explain the different combustion of substances in air and oxygen?

The content of the task for this group of students is similar to the instructions given in the textbook. At the same time, it differs from it in that it contains questions that require students not to perform, but to create creative activities. Students complete such tasks in the first lesson, after which they are ready for more complex independent work.

The second group of students completes a more complex task (second level).
Option 2
Job task: consider ways to collect oxygen depending on its solubility and density.
Work plan:
1) obtain oxygen and collect it by displacing water and air;
2) find out the differences in devices for collecting oxygen above water and displacing air;
3) draw up a report on the work done.
Questions for self-control.
1) In what cases can both methods of collecting gases be used with equal success?
2) How does the solubility of gases affect the choice of method for collecting them?
3) How does the density of gases affect the choice of method for collecting them?
4) Is it possible to determine the method of collecting gases by the shape of the gas outlet tube?

Students in the second group are required to justify the feasibility and necessity of their actions before they begin the experiment. Its description is given in general form, and they must not only be able to conduct an experiment, but also draw independent conclusions from the results obtained. This task requires students to be independent in their work and elements of creative activity.

The third group of students is offered the most difficult task (third level).
Option 3
Job objectives:
1) check the possibility of obtaining oxygen from the following substances: KNO 3, H 2 O 2, KMnO 4;
2) find out the conditions for the decomposition reaction for each of these substances;
3) establish which of these substances is most suitable for producing oxygen in the laboratory.
Work plan:
1) list the substances from which oxygen can be obtained in the laboratory;
2) name (or assume) optimal conditions for obtaining oxygen from the substances listed above;
3) develop a plan and independently conduct an experiment to test theoretical assumptions;
4) draw up a report on the work done.
Questions for self-control.
1) What substances can be used to produce oxygen in the laboratory and in practice?
2) What factors influence the choice of substances to produce oxygen in the laboratory and in practice?

Completing this task requires students not only to be able to theoretically substantiate phenomena and generalize the results obtained, but also to obtain the necessary information from scientific and popular science literature. This task is creative in nature.

§ 4.2. The role of observation in the formation process
experimental skills

Observation promotes direct sensory perception of the substances and phenomena being studied. The information obtained in the process of contemplation arouses cognitive interest and contributes to the formation of independence in the knowledge of the surrounding reality. Observation develops observation, logical thinking, and speech. However, observation gives only an external idea of ​​substances and phenomena and does not reveal their inner essence. Attention is concentrated primarily on individual substances and phenomena, and the cause-and-effect relationships between them are not sufficiently disclosed, which limits one’s horizons.
Closely related to observation is experiment, which makes up for this deficiency. With its help, students find out not only the external features of substances and phenomena, but also the internal structure of substances, reveal the essence and patterns of chemical phenomena.
Consequently, if on the basis of observations mainly substantive concepts are formed, then on the basis of experiment - chemical concepts.
The ability to observe ongoing phenomena and processes should be taught continuously. At the same time, it is necessary to ensure that students pay attention not only to external changes, but also at the same time comprehend the inner essence of the occurring phenomena.
By observing, under the guidance of a teacher, the conditions of experiments, signs of reactions and the resulting products and analyzing the results obtained, students enrich their understanding of chemical transformations and processes, and by explaining the reasons that caused them, they learn to apply the acquired theoretical knowledge in practice.

TABLE OF CONTENTS

Functions and forms of school chemical experiment
Requirements for educational equipment intended for conducting chemical experiments
Functions of a school chemistry experiment
Forms of school chemical experiment
Requirements for educational equipment for a school chemistry experiment

Setting up demonstration experiments
Equipment for demonstration experiments,
Specialized instruments, apparatus, installation
1. Devices for demonstrating experiments with substances harmful to health without exhaust devices
2. Set for demonstrating experiments in electrochemistry
3. Devices for demonstrating experiments using high voltage electric current
4. Piezoelectric high voltage source
5. Device for demonstrating the dependence of the rate of a chemical reaction on various conditions
6. Devices for the production of haloalkanes and esters
7. Equipment for projecting experiences and objects onto a screen
8. Attachment to a graphic projector for demonstrating quantitative experiments
9. Measuring instruments
10. Electric heating devices
11. Electrical supply kit for the chemistry room KEH-10

Demonstration experiments in standard devices and installations
Synthesis of hydrogen chloride and production of hydrochloric acid
Preparation of sulfur (IV) oxide and its oxidation to sulfur oxide
Ammonia synthesis
Catalytic oxidation of ammonia
Obtaining ammonium nitrate
Interaction of iron with water
Study of the electrochemical voltage series of metals
Metal corrosion and corrosion protection
Catalytic decomposition of hydrogen peroxide
Kerosene cracking

Demonstration experiment in special devices and installation
Illustration of the law of conservation of mass of substances
Determination of oxygen content in air
Liquid distillation
Water synthesis
Diffusion of gases through a porous vessel
Adsorption
Electrolysis of water and aqueous solutions
Determination of electrical conductivity of substances
Observing the movement of ions
Experiments in electrical discharges
Obtaining ozoia
Obtaining nitrogen oxides from air
Decomposition of methane in a spark discharge
Study of thermal phenomena
Dependence of the rate of a chemical reaction on conditions
Experiments with toxic substances
Preparation of halondoalcaps and esters
Quantitative experiments projected on a screen

Technique and methodology of student experiment

Characteristics of equipment for student experiment 103
Laboratory experiments and practical exercises 113

Topic 1. Initial chemical concepts
Practical lesson. For an introduction to laboratory equipment, see Safety rules for working in a chemical laboratory
sweat
Practical lesson. Techniques for handling heaters and heaters
Laboratory work. Consideration of substances' chemical properties
Practical lesson. Cleaning contaminated

Topic 2. Oxygen, oxides, combustion
Practical lesson. Production and properties of oxygen

Topic 3. Hydrogen, oxygen, salts
Laboratory work. Production of hydrogen and study of its properties
Practical lesson. Exchange reaction between copper oxide (11) and sulfuric acid 136

Topic 4. Water, solutions, bases 138
Laboratory experience. Electrolysis plants
Practical lesson. Preparation of a solution with a certain mass fraction of the dissolved substance and a given molar concentration 139

Topic 5. Generalization of information about the most important classes of inorganic compounds 141
Solving experimental problems on the topic: Generalization of information about the most important classes of inorganic compounds

Topic 8. Halogens 142
Laboratory experience. Displacement of halogens by each other from solutions of their compounds
Practical lesson. Preparation of hydrochloric acid and experiments with it 143 Practical lesson. Solving experimental problems on the topic “Halogens” 146

Topic 1. Electrolytic dissociation
Laboratory experiments. Testing substances for electrical conductivity
Laboratory experience. Movement of ions in an electric field
Practical lesson. Solving experimental problems on the topic “Electrolytic dissociation”

Topic 2. Oxygen subgroup
Laboratory experience. Preparation and properties of ozone.
Practical lesson. Solving experimental problems on the topic “Oxygen subgroup”

Topic 3. Basic laws of chemical reactions. Sulfuric acid production 155
Laboratory work. Dependence of the rate of chemical reactions on conditions

Topic 4. Nitrogen subgroup
Laboratory experiments. Familiarization with nitrogen and phosphorus fertilizers.
Practical lesson. Preparation of ammonia and experiments with it, Understanding the properties of an aqueous solution of ammonia. Practical lesson. Determination of mineral fertilizers Practical lesson. Solving experimental problems on the topic “Nitrogen subgroup”

Topic 5. Subgroup of carbon
Practical lesson. Obtaining carbon monoxide and studying its properties
Carbonate recognition

Topic 6. General properties of metals
Laboratory experience. Electrolysis of solutions of copper (P) chloride and potassium iodide
Laboratory experience. Electrochemical corrosion of metals Practical lesson. Solving experimental problems in the sections “Alkali metals. Calcium"
Practical lesson. Iron and its compounds Practical lesson. Solving experimental problems on topics 6, 7, 8

Topic 2. Saturated hydrocarbons
Practical lesson. Qualitative determination of carbon, hydrogen and chlorine in organic substances

Topic 3. Unsaturated hydrocarbons
Practical lesson. Preparation of ethylene and experiments with it

Topic 6. Alcohols and phenols
Practical lesson. Synthesis of the bromine phase from alcohol

Topic 7. Aldehydes and carboxylic acids
Practical lesson. Preparation and properties of carboxylic acids Practical lesson. Solving experimental problems on the recognition of organic substances

Topic 8. Esters. Fats
Practical lesson. Synthesis of ethyl acetate Practical lesson Solving experimental problems on obtaining and recognizing organic substances

Topic 12. Synthetic high-molecular substances and polymer materials based on them
Laboratory experiments. Experiments with samples of thermoplastic polymers
Practical lesson. Plastic recognition
Laboratory experiments. The relationship of synthetic fibers to solutions of acids and alkalis
Practical lesson. Fiber recognition
Practical lessons. Solving experimental problems on the completed course

General chemistry

Topic 2. Structure of matter
Laboratory experiments. Preparation and properties of complex compounds of copper, zinc, aluminum, silver and iron
Workshop
Work 1. Determination of the equivalent mass of zinc
Work 2. Determination of the molar mass of carbon monoxide (IV)
Work 3. Softening water using ion exchangers
Work 4. Hydrolysis is salty
Work 5. Study of the reactivity of metals using the semi-micro method
Work 6. Manufacturing a galvanic cell 206
Work 7. Determination of the chemical activity of acids and comparison with the degree of their dissociation 207
Work 8. Study of the effectiveness of inhibitors 208
Work 9. Determination of the heat of solution 210
Work 10. Determination of the heat of hydration 211
Work 11. Hydrolysis of starch 212
Work 12. Production of ethane by electrolysis of a solution of sodium acetate 213
Work 13. Preparation of tetraammine copper (II) sulfate 214
Applications 216
Literature for teachers 235

INTRODUCTION
Teaching the basics of chemistry at school cannot be improved without the appropriate organization of a school chemical experiment.
A chemical experiment - a source of knowledge about matter and chemical reactions - is an important condition for enhancing the cognitive activity of students, cultivating a sustainable interest in the subject, forming a dialectical-materialistic worldview, as well as ideas about the practical application of chemical knowledge.
In the improved chemistry program, the role of all types of school chemical experiments, especially student ones, has been strengthened.
The implementation of the experimental part of the program requires high and comprehensive professional training from the chemistry teacher, a deep understanding of the role of chemical experiment in the educational process, and creative activity in the application of effective teaching methods.
Of course, to conduct an experiment at a high scientific, theoretical and methodological level, a variety of equipment is needed, including the latest technical means.
The presence of a set of educational equipment necessary for the implementation of the chemistry program, the teacher’s ability to use it rationally and effectively, select the necessary tools for the lesson, independently produce some of them and correctly include them in the lesson also constitute the most important conditions for organizing a chemical experiment at school.
The book focuses on the issues of material support for a school chemical experiment, the influence of scientific and technological progress on modern equipment, techniques and methods for conducting various types of experiments using traditional and new equipment.
The manual reflects the requirements of the school reform for the chemistry experiment, namely: to include new equipment for the chemical experiment, developed taking into account scientific and technical achievements and the best practices of schools; show the organization and conduct of a chemical experiment based on kits and sets of standardized units and parts for the installation of various instruments and installations; provide for variability in setting up a chemical experiment, carried out using new and modernized equipment, as well as taking into account local conditions and requirements for self-equipment, which is especially important in teaching chemistry; identify the possibilities of using various equipment to implement interdisciplinary connections.
All this is aimed at optimizing chemistry teaching and provides for: reducing the time for preparing and conducting an experiment; convenience, reliability, safety of chemical experiments; expanding the didactic possibilities of student experiment.
In the methodological literature, considerable attention is paid to the chemical experiment. The characteristics of the chemical experiment are carried out in three aspects: equipment for the school chemical experiment; experimental technique; experimental technique. Despite some differences between these works, they discuss the technique and methodology of the experiment simultaneously.
In this manual, to familiarize teachers with the modern arsenal of equipment for chemical experiments, the characteristics of the educational and material base for demonstration and student experiments are given separately from the methods and techniques for performing experiments, many of which can be carried out using kits and multifunctional devices. The characteristics of the educational and material base of chemical experiments include modernized, new and most important promising developments of equipment created on the basis of school practice, analysis of Soviet and foreign literature on this problem, as well as research work of the Scientific Research Institute of Shotso of the Academy of Pedagogical Sciences of the USSR.
Since the issues of equipping a school chemical laboratory are described quite fully in the book “Chemistry Cabinet”, this manual will focus only on those requirements for the classroom and its equipment that determine the inclusion of new and modernized equipment.
The book is intended for chemistry teachers familiar with laboratory techniques. Therefore, it does not contain instructions for performing basic operations. In case of difficulties, readers will be able to refer to numerous manuals on laboratory work techniques, for example, the book by P. I. Voskresensky “Laboratory Work Techniques”. However, when new experiments or experiments with upgraded equipment are recommended, instructions for their implementation are given in sufficient detail. In all cases, great attention is paid to the conditions that ensure the safe execution of experiments.
The manual presents experiments included in the school chemistry curriculum, as well as those that go beyond its scope. The teacher can use them in extracurricular activities and extracurricular activities. The proposed experimental options make it possible to expand the use of experiments in various conditions, to study the features of chemical processes, and to present them in a variety of ways. This approach will allow teachers to use chemical experiment more effectively, taking into account the specific conditions of each school.
The numbers in square brackets are the numbers of literary sources given at the end of the book.

FUNCTIONS AND FORMS OF SCHOOL CHEMISTRY EXPERIMENT. REQUIREMENTS FOR TRAINING EQUIPMENT DESIGNED FOR CHEMICAL EXPERIMENTS
FUNCTIONS OF SCHOOL CHEMISTRY EXPERIMENT
An experiment allows you to identify and study the most significant aspects of an object or phenomenon using various tools, instruments, and technical means under given conditions. The experiment can be repeated by the researcher if necessary. This largely determines the main function of a scientific experiment: obtaining reliable data about the surrounding reality. An educational experiment differs from a scientific experiment in that its results are known, the conditions for its conduct are selected so that in the process of conducting experiments or observing them, students must detect known signs of a reaction and arrive at the expected results.
A training experiment is technically simpler and, as a rule, limited in time. In a school chemistry course, experiment is a unique object of study, a research method, a source and means of new knowledge. It is characterized by three main functions: cognitive - for mastering the basics of chemistry, posing and solving practical problems, identifying the meaning of chemistry in modern life; educational - for the formation of a materialistic worldview, conviction, ideological need for work, orientation of students towards working professions; developmental - for acquiring and improving general scientific and practical skills.
Chemical reactions are the main object of study of chemistry. Experiment and related observations are necessary already in the formation of initial chemical concepts. Their role increases in the study of theoretical issues of chemistry (the law of conservation of mass of substances, the laws of the flow of chemical reactions, etc.), in determining the properties of simple substances and compounds of elements of groups I - VIII of the periodic table, the most important classes of organic substances, as well as in identifying the genetic connections of the most important classes of inorganic and organic substances.
Familiarization with chemical experiment as a method of scientific research, mastering the skills of chemical experimentation to obtain new knowledge and apply it in practical activities play an important role for the formation of a materialistic worldview of students, understanding the role of science and scientific facts in the construction of a communist society.
The school chemical experiment is also of great educational importance for the polytechnic training of students: familiarizing them with the basics of chemical production, its features, the conditions for the occurrence of chemical reactions, and the chemicalization of the national economy.
Based on the perception of observed phenomena, students form ideas and then concepts. This inductive path of knowledge is characteristic of the initial stage of learning chemistry. Gradually, this relatively slow path of knowledge is complemented by another - deductive. After students have armed themselves with theory and acquired practical skills, the experiment becomes not only a source of knowledge of new facts, but also a method of testing judgments and finding the unknown (for example, when solving experimental problems).
The same experiment is used differently at different levels of student preparation. It follows from this that it is advisable to repeat chemical experiments, paying special attention to those aspects of them that are the subject of study in a given educational situation.
In some experiments, the phenomenon is accessible to direct perception. In others, the objects and phenomena being studied are not directly perceived by the senses and can only be detected with the help of instruments or special instruments.
To understand the essence of the subject or phenomenon being studied, a chemical experiment is often supplemented with other visual aids - tables, models, screen aids.
Thus, the chemical experiment permeates all the topics of the school chemistry course, contributing to the disclosure of its content and being a unique teaching method. For the successful manifestation of the cognitive, educational and developmental functions of a chemical experiment, its technical equipment, rational organization of experiments and their inclusion in the educational process play an important role.
It is obvious that the effectiveness of the experiment depends on: setting a specific goal and task that must be solved with the help of experiment; building a rational observation plan; ability to record observation results; ability to analyze and summarize the data obtained; the presence and rational selection of tools and means with which the teacher stimulates and manages student observation. Therefore, organizing targeted observation, developing observation skills, the ability to comprehend the results of observations and retain processed information in memory constitute one of the most important tasks of a chemical experiment.
Comprehension and understanding of educational material involve not only the registration and accumulation of observational and experimental data, but also their correct interpretation, the establishment of cause-and-effect relationships, patterns, and the essence of the objects and phenomena being studied. The success of the work largely depends on how correctly the nature of the activity of the teacher and students, the location of the chemical experiment, and the most appropriate forms and methods of its implementation in the classroom are determined.

FORMS OF SCHOOL CHEMISTRY EXPERIMENT
In the practice of teaching chemistry, it is traditional to divide a chemical experiment into a demonstration experiment, carried out by a teacher, and a student experiment, performed by schoolchildren in the form of laboratory experiments, practical exercises, and solving experimental problems. This classification is based on the activities of the teacher and students.
Demonstrations are used primarily in cases where students have not previously encountered the objects and phenomena being studied and are not prepared for observation. In these cases, one should not only show the object being studied, but also organize observation and direct it in the right direction. Students do not always perceive what is necessary, even with good visibility of an object or phenomenon, if the observation is not organized.
Demonstration is necessary if the objects being studied are dangerous or complex and, therefore, cannot be used for independent work by students.
Correctly conducting demonstrations in chemistry lessons is a necessary prerequisite for organizing various types of independent work. During the process of demonstration, especially a demonstration experiment, the teacher organizes student observation, shows the correct techniques for handling laboratory equipment, and focuses students’ attention on the feasibility and principle of its operation, the conditions for conducting experiments, and safety precautions.
A demonstration is a kind of visual instruction, on which the teacher has to spend a lot of time during the teaching process. Visual instruction based on imitation of the teacher, implemented with the help of various aids, including instruments, tables, diagrams, and screen aids, reduces the time for developing chemical experiment skills and contributes to the correct execution of the student experiment.
The leading role of demonstration also remains in the case when the time allotted by the curriculum does not allow organizing independent work, which usually takes two to three times more time than demonstration. The lack of educational equipment for conducting student experiments and the poor organization of the chemistry laboratory, which does not allow proper independent work, also force teachers to turn to demonstration experiments.
The student experiment consists of laboratory experiments performed frontally or in a group in the process of studying, consolidating and testing new material, as well as practical exercises, solving experimental problems according to options after studying individual topics of the program. A promising form is a workshop conducted in the form of separate generalizing works after completion of the entire chemistry course. Experimentation occupies a special place in elective classes and in extracurricular activities.
In a chemical experiment, both demonstration and student, various masses of substances taken for experiments are used in solid, liquid and gaseous states, which requires appropriate equipment and the ability to handle it.
Conventionally, the following masses of the substance taken for work are distinguished: macroquantities (0.05 - 0.5 g), semi-microquantities (0.01 - 0.05 g), microquantities (0.1 - 10 mg). In this regard, they talk about macro-, semi-micro- and micromethods for determining (analysis) of a substance. In all these cases, the same chemical reactions are carried out, the same concentrations of solutions are used, but in different volumes and equipment of different sizes. Thus, in the semi-micro method, volumes of 0.1 - 1 ml of solution are used, for which miniature pipettes, burettes, test tubes (conical), porcelain or glass plates with recesses (for drop analysis), and reactive paper strips (for example, indicator) are used.
As is known, in student experiments they traditionally use the macromethod, in which ordinary test tubes and devices made on their basis are used. Recently, along with the macromethod, school chemistry classrooms have been equipped with devices for conducting experiments with small amounts of substances in small test tubes, on glass or porcelain plates with indentations, etc.
The method of small quantities of substances allows you to combine the macromethod and droplet analysis in a student experiment, while achieving maximum safety of the experiments and their clarity. Solid reagents are taken with special dispensing spoons. The mass of reagents on average does not exceed 1 - 1.5 g (one dispenser contains on average 0.5 g of dry matter). Measuring liquid substances is carried out using pipettes that allow you to take from 1 - 2 drops to 5 ml (the approximate volume of a whole pipette is 1 ml).
Working with small quantities of substances has advantages over the macromethod: the time of conducting the experiment is reduced, the consumption of reagents and materials is reduced, and the possibility of using expensive and highly pure reagents opens up.
Small amounts of substances are also used in demonstration experiments, if experiments are projected onto a screen (for example, in Petri dishes using a graphic projector).
When characterizing an experiment, not only masses are taken into account, but also the features of carrying out physical, physicochemical and chemical operations with solid, liquid and gaseous substances.
In the school chemical laboratory, when preparing an experiment in lessons, elective classes, and club activities, the teacher, laboratory assistant, and students carry out the above operations. Knowledge of these operations and the correct techniques for performing them is necessary for the selection of equipment, proper installation of instruments and installations, and the safe performance of experiments.
Operations with solids: weighing, drying, sublimation, grinding, cracking (dry distillation), heating, determination of physical properties and constants (dielectric properties of polymers, density, melting or solidification temperature, thermal effect of reaction, hardness, electrical conductivity) , calcination, separation of mixtures, grinding (in a mortar), decomposition (pyrolysis), mixing, adding to the flame (determination of lithium, sodium, potassium, calcium, barium, copper ions by the color of the flame).
Operations with solids and gases: roasting, oxidation of metals, adsorption of gases (and vapors), gas chromatography.
Operations with liquid substances: evaporation and evaporation, drying, distillation, heating, purification, determination of density (with a hydrometer, etc.), determination of boiling point, stirring, introduction into a flame (flame coloring), determination of active acidity (with indicators, etc.), obtaining absolute (anhydrous) alcohol, separation of liquids (separating funnel, distillation, chromatography), cracking (pyrolysis), determination of electrical conductivity, electrolysis (water, salts, solutions), storage and transfusion of liquids.
Operations with liquids and gases: dissolution of gases, separation of gases from liquids, atomization of liquids with a gas stream, washing and drying of gases.
Operations with solid and liquid substances: adsorption of solutes, weighing, evaporation, drying, diffusion, ion exchange, crystallization from solution, neutralization, preparation of solutions, dissolution of solids, melting and solidification, precipitation, complexation, separation of mixtures (filtration, chromatography, extraction), production of colloids, coagulation.
Operations with gases: adsorption, handling of flammable gases, heating, purification and absorption of gases, drying of gases, determination of air composition, production, collection of gases (over water, air displacement), gasometer charging, combustion of gases, interaction of gases with liquids and solids , diffusion, thermal decomposition of gases, electrical discharges in gases, gas corrosion of metals.
This manual does not cover equipment and techniques for performing the listed operations. These issues are covered in detail in laboratory practice manuals. Many of the operations are given below in the description of various experiments.

REQUIREMENTS FOR TEACHING EQUIPMENT FOR A SCHOOL CHEMISTRY EXPERIMENT
The equipment requirements for a school chemical experiment are dictated by the content and features of its organization in a chemistry classroom. Therefore, before determining what school equipment for a chemical experiment should be, it is necessary to consider the general and specific requirements for staging demonstration experiments, organizing laboratory and practical work, as well as the question of the rational combination of these types of experiments in the classroom.
Visualization and expressiveness of experiments is the first requirement for a chemical experiment. Since any chemical experiment is aimed at realizing the clarity of the objects and phenomena being studied, it is necessary to determine in what form it will be most effective: in the form of a laboratory experiment, a regular demonstration, projection on a screen, or in a certain combination thereof.
The educational and material base must provide conditions for the rational choice of the necessary forms of chemical experiment. The purpose of the performance and the content of the experiments should be clear to every student. The experiment must be clearly visible; the dimensions of the instruments, parts, and their placement on the work table must ensure good visibility of the observed phenomena.
The second requirement: chemical experiments must be accessible to perception and always convincing, and should not give students a reason for misinterpretation.
Educational equipment must therefore ensure that chemical experience is simple, demonstrable and reliable. When choosing a device, its design features must be taken into account. So, for example, demonstrating the interaction of sodium with water in a crystallization glass or bowl, as is usually done in schools, does not reveal all the signs of the reaction: the melting of sodium as a result of the released heat of reaction, the transformation of sodium into a ball, its movement along the surface of the water, the release of gas . This makes it difficult to explain the experiment and study the properties of the alkali metal. The combination of conventional demonstration and screen projection makes the experience visual and authentic.
The design of a device or installation must provide not only the conditions for conducting a chemical reaction, but also the ability to identify and display visible and hidden signs of the ongoing process. When demonstrating a neutralization reaction, for example, by pouring an acid solution into an alkali solution using litmus or phenolphthalein, the neutralization process is detected by a change in the color of the indicators: litmus becomes violet, and the crimson color of phenolphthalein becomes colorless. The release of heat remains hidden from the observer. The use of an electric thermometer in a demonstration experiment makes it possible to characterize the reaction more conclusively.
The clarity and reliability of the demonstration of experiments is determined by the technique of its production.
In the school chemistry experiment, there were previously no precise measuring instruments. However, today it is impossible to introduce students to scientific methods without them. To use such devices, it is enough to be able to use them correctly, without delving into the details of their design.
These are primarily electrical and electronic devices used in conducting a number of experiments in electrochemistry, including those involving the use of high voltage current.
Each experiment carried out by a teacher or student must be trouble-free, and the equipment for its implementation must be expensive. A failed demonstration disrupts the flow of the lesson, causes frustration among students, and often leads to distrust of the teacher. The reasons for failed experiments are varied. One of them is the technical imperfection of devices, as well as their individual parts and assemblies.
The reliability of instruments and installations thus depends on their technical perfection. To do this, it is necessary to have in each chemistry classroom sets of standardized utensils in strictly necessary and sufficient quantities to carry out various types of chemical experiments; sets of universal units and connecting parts ensuring tightness and ease of installation. These include a variety of connections: rubber, glass joints (ground and bent), rubber and plastic seals.
The reliability of devices and installations also depends on their correct storage and transportation. For example, glassware and accessories often fail due to improper storage in the cabinet (without stacking them in cabinets).
The reliability and technical excellence of shizhio instruments and installations ensure compliance with safety regulations when carrying out chemical experiments. The implementation of this requirement depends, of course, not only on the state of the educational and material base of the chemistry classroom, but also on the extent to which the teacher has mastered the technique of chemical experiment, on his knowledge of the entire arsenal of educational equipment necessary for the experiments, pt precision and work culture.
The devices in which experiments are carried out must be prepared in advance, tested repeatedly, and the operating manuals or passports of devices and installations must be carefully studied by the teacher.
Safe work is determined by regulatory documents, in particular “Safety rules for chemistry classrooms (laboratories) in secondary schools of the USSR MP system.” It should be noted that in most cases the danger is caused by the negligence of the experimenter, violation or direct disregard of the operating instructions for devices or installations. Heating flammable liquids over an open flame, incorrect selection of quantities, concentrations and volumes of reacting substances, storing flammable and explosive gases in glass gasometers, demonstrating the explosion of gases in glass vessels, connecting electrical appliances designed for low voltage to the network, using technically imperfect home-made electrical appliances - the most common causes of dangerous situations.
In industrial devices and installations, safety requirements are determined by the relevant regulatory documents V. are reflected in the design features of this device. For example, providing electrical appliances with protective covers, pole plugs (preventing the device from being plugged into a regular power outlet), mechanical locking of sockets (locking them in the desired position), etc.
Homemade devices and installations can be used in school only in cases where they are technically reliable and safe. One of the requirements for a school chemical experiment is its short duration, which is determined by the limited time of the lesson.
When setting up an experiment in a lesson, the following must be taken into account: the feasibility of including experiments at a certain stage of the lesson, the need to explain them (including using other teaching tools), the possibility of repeating the experiment to correct the observation and obtain reliable results.
The rational design of devices and installations, their correct use in accordance with the pace and stages of the lesson ensure the achievement of set goals in a precisely calculated time frame. For example, savings in teaching time can be achieved not only by reducing auxiliary operations when installing a device or installation, but also due to the convenience and speed of their implementation. This is greatly facilitated by the well-thought-out design of the device. For example, heating is one of the most frequently repeated operations. Therefore, it is necessary to create heaters that would provide the ability to operate in predetermined modes.
The average duration of a laboratory experiment and a separate demonstration should not exceed 5 - 6 minutes of a lesson, and when performing practical work - 15 - 20 minutes. Delaying the experiment time beyond the given norms reduces interest in the experiment, disrupts the rhythm and structure of the lesson, and does not allow the results of the research to be formalized.
Some experiments (for example, on metal corrosion) require a long time. Such an experiment is carried out in stages; in the first lesson, the conditions of the experiment are discussed and the implementation is carried out; in the next one or two lessons, the results obtained are recorded. To carry out such experiments in parallel classes, a larger amount of equipment of the same type is required, which can be replaced with a similar one for its intended purpose (for example, beakers can be used instead of flasks).
It must be taken into account that educational equipment for a chemical experiment can function successfully if certain conditions are created in the chemistry classroom; in particular, there are appropriate communications connections, halo, water and electricity supplies have been established, teacher and student workplaces have been rationally organized, and the system for placing and storing educational equipment has been carefully thought out.
These and other questions are covered in the book “Chemistry Cabinet”. Therefore, here we consider mainly new issues regarding the implementation of methodological requirements and safety rules when performing a chemical experiment. These primarily include modern electrical equipment in the chemistry classroom, since conducting experiments in electrochemistry, as well as the operation of electric heaters, require not only reliable, but also safe instruments, as well as appropriate conditions for their use in the learning process.
The composition of electrical equipment and the rules for its operation in a school chemistry classroom are determined by the following regulatory documents; “Standard lists of educational visual aids and educational equipment for secondary schools” for the XII five-year plan (hereinafter referred to as “Lists-12”), Section; chemistry; Safety regulations for chemistry classrooms (laboratories) in secondary schools of the USSR Ministry of Education; GOST “School equipment. General safety requirements."
The electrical equipment of the chemistry classroom includes stationary equipment (electrical supply kits for the chemistry classroom, KHE, power input panel, water distillation apparatus) and portable equipment (various electrical appliances and installations, projection equipment). All electrical appliances are divided into four classes according to the method of protection against electric shock: OT, I, II, III. In the chemistry classroom, the teacher works with electrical equipment belonging to classes I, II, III.
The first class includes stationary devices and installations that require grounding. The second class includes all kinds of electrical appliances (stoves, demonstration heaters) that are connected to the network, but they are not grounded, since they have double or reinforced insulation.
The third class includes devices that do not have either internal or external electrical circuits with a voltage above 42 V (laboratory heaters such as NLSH, NPU, NPESH, see, pp. 108, 109).
Teachers and laboratory assistants work with instruments and installations of the first and second grades. Students use only third grade equipment for laboratory and practical work.
In new-built schools, stationary equipment powered by three-phase current is installed by construction organizations. However, in most schools, specialists have yet to install it. The most convenient for this purpose is the wall adjacent to the laboratory room.
Using the power supply kit for the chemistry classroom (KEH), the teacher's demonstration table is powered with an electric current of alternating voltage 220 V and 42 V and the students' workplaces with an electric current of alternating voltage 42 V. The KEH is equipped with a residual current device of the UZOSH type.
To perform experiments in electrochemistry that require a DC voltage of up to 12 V, you should use the “Practicum” power supply (from the physics room).
To power electrical appliances, two sockets are installed on the demonstration table specialized for the chemistry classroom: 220 V and 42 V at a distance of at least 1.5 m from the water tap (for example, on the side wall of the demonstration part of the table).
To power electrical appliances, one 42 V outlet is placed at students’ workplaces (for example, on the side panel of the table). It has slot-like holes located perpendicular to each other and designed to accept a plug with a corresponding arrangement of flat plugs.
When creating and using homemade and industrial devices, you must remember the following safety requirements (according to the above GOST):
1. In closed current-carrying systems, the permissible voltage for students is no higher than 42 V AC and DC; for the teacher - -220 V AC and 110 V DC.
2. In open current-carrying systems (in devices with bare parts of conductors and when working with electrolytes), a voltage of no higher than 12V AC and DC is allowed for teachers and students.
3. When working with electrolytes in vessels closed with special devices (casings, lids, etc.), voltage for student experiments is allowed up to 42 V AC and DC and for teacher experiments - PO V.
4. The maximum value of electric power consumption in the chemistry classroom should not exceed 2.2 kW (for example, 20 test tube heaters, a projection apparatus and a distillation apparatus cannot be turned on simultaneously).
The teacher should take note that in the chemistry classroom, sockets (220 V) and switches, according to the rules for electrical installations, must be located at a height of 1.8 m from the floor.
A mandatory requirement when working with electrical equipment is a preliminary thorough study of the instructions for its operation.
It must also be remembered that electric current is turned on at students’ laboratory tables only during experiments. During non-working hours, workplaces must be de-energized.
The electric current is switched on using a switchboard located in the laboratory room. The shield is equipped with a general power switch and a power indicator.
To carry out all types of experiments, it is necessary that in each office sets of instruments, installations, glassware and laboratory supplies are created, always ready for use.
The equipment supplied to schools in accordance with the current List of educational equipment allows each chemistry classroom to independently create such kits if it was not possible to purchase them ready-made.
To successfully implement a chemical experiment using the new program, the following kits are required.
For the demonstration experiment: a set of low-inertia electric heaters for liquids and solids up to a temperature of 300°C (in flasks, beakers, crucibles, cups); a set of utensils, parts and assemblies for the installation of devices and installations in which chemical reactions are carried out under normal conditions; a set of parts and assemblies for experiments with harmful substances without traction; counting and measuring kit (measurement of mass, temperature, time, voltage, pI and carrying out arithmetic calculations on a demonstration light display); a kit for carrying out catalytic reactions (a set of catalyst tubes and heaters, catalysts on carriers); kit for experiments with gases (flammable and explosive); kit for experiments with high voltage electric current; a set of specialized instruments and apparatus (for obtaining and storing gases, obtaining distilled water, illustrating some laws, etc.); a set of components and parts for projecting experiments on the screen; a set of 250 ml bottles for reagent solutions; a set of bottles with a lower tube of 1 - 2 liters for storing a supply of reagent solutions.
For a student experiment: a set for laboratory experiments and practical work, including a set of dry reagents in jars and their solutions in flasks for constant and occasional use; small set of accessories; small volume set of dishes (25 - 50 ml); a set of joints and assemblies for mounting various instrument options; a set of auxiliary laboratory equipment (washing bowls, waste jars, test tube racks and laboratory racks for fixing instruments, glassware and accessories).
These kits should provide the opportunity for students to variably and safely perform laboratory and practical work in various ways: using macro and micro amounts of reagents, the drop method, using substances in various states of aggregation.
When organizing students’ workplaces, the teacher must determine the equipment placement option that best suits his style of work: sets permanently attached to the laboratory table or handouts provided in trays before practical work.
The system for placing reagents, glassware and accessories on laboratory tables or when stored in a laboratory should provide students with a quick and correct selection of bottles with reagents, the necessary components for installing instruments, order and convenience in the workplace.
The same requirements apply to the teacher’s workplace, and above all to the demonstration table.
Particular attention should be paid to the organization of the preparation table in the laboratory, storage and placement of reagents, glassware, accessories, trays with handouts in sectional cabinets.
Dishes and glassware must be stored in containers (made of foam rubber or polystyrene), which can be made by students under the guidance of chemistry and vocational education teachers.
According to the requirements of the school reform, the range of demonstration experiments (projecting chromatography experiments on a screen, etc.) and student experiments (electrolysis, ozone production, etc.) has been expanded.
The requirements of scientific and technological progress - to raise experiment as the basis for the study of chemistry to a higher level, to ensure its clarity, evidence, reliability, safety, to show with the help of educational equipment the application of the laws of chemistry in chemical technology, as well as the connection of chemistry with physics and biology - determine the main directions for the development of educational equipment for school chemical experiments:
creation of multifunctional devices that allow several experiments to be carried out in one device. These devices include standardized units and parts (modules), which provide the student teacher with the opportunity to quickly and conveniently install the necessary installations for demonstrations and independent work of students;
creation of new electrical appliances: specialized low-inertia heaters; automatic and auxiliary devices (for forced ventilation, lighting control, curtains, etc.);
optimal miniaturization of educational equipment, which ensures savings in materials and allows students to rationally carry out independent work with small quantities of substances;
the use of electronic technology to record not only qualitative, but also quantitative results of experiments;
creation of instruments and installations for interdisciplinary connections between chemistry and physics and biology;
the use of new structural materials and technologies in the production of educational equipment: germanium semiconductors, strain gauges that convert gas pressure into an electrical signal, plastics, glass parts with a curved surface, and in the future - liquid crystals, optical fiber materials;
carrying out a school chemical experiment on the basis of typical, standard equipment, ensuring rational compatibility of individual parts and assemblies, sets as a whole and the ability to quickly and correctly install various options for devices and installations in a school chemistry classroom.
In this manual, the authors focus mainly on the use of new and modernized equipment, which makes it possible to improve the technique and methodology of school chemical experiments.

CONSTITUTION OF DEMONSTRATION EXPERIMENTS

EQUIPMENT FOR DEMONSTRATION EXPERIMENTS
Typical components and parts, sets of utensils and accessories for installation of devices and installations
In school practice, various chemical laboratory glassware and laboratory supplies (glass and rubber tubes, taps, screw and spring clamps, fireproof gaskets, triangles for crucibles, etc.) are used to conduct a chemical demonstration experiment. This equipment is used to conduct both simple and more complex experiments in devices and installations. The first group of experiments includes: separation of a mixture of substances; interaction of water with phosphorus and calcium oxides and testing of the resulting hydroxides with indicators; sublimation of iodine; exchange reactions (production of insoluble hydroxides and study of their properties, salt precipitation, etc.); the ratio of saturated hydrocarbons to potassium permanganate solution, alkalis, acids; interaction of glycerol with sodium; solubility of phenol in water at normal temperature and when heated; the ratio of stearic and oleic acids to bromine water and a solution of potassium permanganate and some other experiments. To set them up, flasks, beakers, cylinders with plates, demonstration tubes with a capacity of 50 ml (type PH-21), crucibles, evaporation bowls, etc. are used.
The technique for working with this equipment is simple and well known to the chemistry teacher, and therefore the authors do not disclose it.
Another group of demonstration experiments (about 40) requires the use, along with chemical glassware and laboratory supplies, of special parts and assemblies, which are usually installed by the teacher (laboratorian) himself, if the school does not have special industrial kits.
The preparation of such parts and assemblies in the form of kits for various purposes, their rational placement in the chemistry classroom are necessary conditions for the successful implementation of experiments of varying complexity.
Typical components of educational instruments and installations include various reactors, devices for transferring reaction products (plugs with tubes, joints, extensions, cones, etc.), and receivers. Somewhat less commonly used are vessels for cleaning, drying gases, refrigerators, a Buchner funnel and a Bunsen flask for filtering under vacuum (Fig. 1).
Reactors. Among the reactors, the most common are two types: the first type is a reactor in the form of various flasks (round-bottom flasks, flasks with an extension - Wurtz flasks, etc.); the second type is a reactor in the form of a tube located horizontally or vertically (see flyleaf I).
In complex installations, both types of reactors are sometimes used.
Flyleaf I presents reactors in the form of various flasks with the most commonly used components: a stopper with tubes, a funnel, a thermometer. In devices assembled using the appropriate parts, it is possible to carry out a number of demonstration experiments with the production of gases or volatile substances: the production of chlorine, hydrogen chloride, ammonia, sulfur oxide (IV), acetylene by the carbide method, nitration of benzene, etc. (see flyleaf P).
The choice of reactor flask is determined by the nature of the demonstration experiment. As a rule, round-bottomed flasks (flask capacity 200 - 250 ml) are used because they are more durable and can withstand gentle heating directly from the burner flame. For many experiments (distillation of liquids, production of gases, etc.), flasks with an extension (Wurtz flasks) are convenient. The flasks must be tightly closed with rubber stoppers or stoppers with the necessary parts.
A dropping funnel with a stopper (endpaper G) is the part most often used in the production of gases. Often, to equalize the pressure inside the flask and atmospheric pressure, the end of the funnel is immersed in a small test tube located at the bottom of the reactor flask. However, the most convenient to use is a reactor flask, equipped with a spherical funnel with a gas outlet tube (endpaper I): In a two-neck flask, an industrially manufactured funnel for working with harmful substances (type VVRV) is used (endpaper I) The presence of a thin section, unfortunately, limits it application, since the funnel is supplied to schools complete with a flask that has the same grind.
In some cases - (for the distillation of liquids) a thermometer inserted into the stopper is required (endpaper I). A stopper connected by a small test tube through glass and rubber tubes is convenient for introducing small amounts of powdery substances into the reactor flask.
* Using an electric spiral, you can perform a number of experiments in flasks, for example, the thermal decomposition of wood, peat, oil shale, coal, and petroleum products.
Various types of tubes v (see flyleaf I) can also be used as a reactor: straight, calcium chloride (with a ball and arc-shaped), straight reaction tubes with a length of 200 mm and a diameter of 15 - 20 mm (for some experiments longer tubes are required - 400 mm with 25 mm in diameter) made of heat-resistant or quartz glass, as well as iron (straight and curved at right angles) and porcelain.
A number of experiments can be carried out in ordinary glass tubes (tubular reactors) using heating with an open flame. They carry out, for example; demonstrating the decomposition of basic copper carbonate; reduction of copper (II) oxide with hydrogen; catalytic oxidation of sulfur oxide (IV) to sulfur oxide and ammonia to nitrogen oxide (II); quantitative experiment: determination of the mass of sulfur (IV) oxide formed during the combustion of a certain mass of sulfur by increasing the mass of sodium hydroxide that absorbed the resulting reaction product.
Tubular reactors are needed, as a rule, for high-temperature experiments, for reactions in a flow (gas, liquid).
It is not possible to use gas burners in all cases; Therefore, electric heaters have long been used, the description of which is given in manuals for chemical experiments.
It is often recommended to use asbestos to make homemade electrically heated tube furnaces. However, its use in school chemistry classrooms has recently been prohibited. Electric heating using a spiral. Can be used without asbestos. Some experiments are carried out in electrically heated glass tubes (oxidation of sulfur oxide (IV) to sulfur oxide (VI) in the presence of a solid catalyst, ammonia synthesis, catalytic oxidation of ammonia).
The electric spiral can be used in another way. The tube through which the electric spiral is pulled (endpaper L) is filled with a catalyst. In such a reactor, ammonia is oxidized to nitrogen oxides, in the presence of the same catalyst - chromium (III) oxide.
On a ceramic carrier in the same reactor, sulfur oxide (IV) can be oxidized into sulfur oxide (VI).
Reactors should also include special devices for burning gases in each other. They own a universal industrial burner.
Devices for transferring and collecting reaction products. For quick and reliable assembly and disassembly of devices, connecting elements are used in the form of transitions, bends, couplings, lengths, closures, and attachments. From a limited number of such parts, especially when they have ground surfaces, a whole range of devices can be assembled. The most common are interchangeable cone joints. Cones can be made not thick by grinding methods, but also by hot calibration - bending. Thus, a distinction is made between cones with a ground surface (KS) and cones with an unpolished surface (KN). Bent products have a number of advantages over ground ones: greater mechanical strength, do not jam and are easily separated, become less dirty, can work even without lubrication, and are transparent.
Various washing bottles are used to clean and dry gases (see flyleaf I). They are filled with liquid (concentrated sulfuric acid and an alkali solution are most often used) with solid (sodium and calcium hydroxides, calcium chloride) absorbers.
For solid absorbers, calcium chloride tubes with a ball and absorption columns are also used. The latter can be receivers of reaction products, for example, hydrogen chloride and synthetic hydrochloric acid. Various chemical vessels can also be used as receivers: test tubes, flasks, beakers.
Bottles for liquid washers (Drexel, two-necked and three-necked Wulf) are used like this. same as safety vessels for vacuum filtration. To perform this operation, you must have a thick-walled flask with an extension (Bunsen) and a porcelain funnel with holes (Buchner).
Typical units for collecting gases and dissolving them are presented on flyleaf II.
Currently, all typical parts and assemblies for the installation of various instruments and installations are included in special sets produced by industry: a set of chemical laboratory glassware and accessories for demonstration experiments in chemistry (NPH) for incomplete and complete secondary schools and a set of parts and assemblies for installation of devices illustrating chemical production (NDHP-M).
These kits include more than 50 different parts that ensure the installation of not only traditional, but also special instruments and installations for staging all demonstration chemical experiments in chemistry courses in junior and senior high schools.

Specialized instruments, devices, installations
To carry out certain demonstration experiments, specialized instruments, devices, and installations are used. As a rule, these are stationary instruments: an apparatus for producing gases (Kippa), a gasometer, an instrument for electrolysis, a device for demonstrating the dependence of the rate of chemical reactions on conditions, etc.
The installations are assembled from instruments, parts and assemblies of kits and sets of industrial production (sets for experiments with electric current, kits for projecting experiments onto a screen, etc.).
1. Devices for demonstrating experiments with substances harmful to health without exhaust devices. In the school chemistry course there are many experiments on studying the properties of volatile substances harmful to health (chlorine, bromine, hydrogen chloride, hydrogen sulfide, nitrogen oxides, ammonia, carbon monoxide (I) , some organic substances).
It is usually recommended to obtain these substances and become familiar with their properties using iodine traction. The distance of fume hoods from students' work stations and the presence of glare on the glazed surface of the cabinet impair the visibility of demonstrations, but ensure their safety.
One of the directions for improving such demonstrations was the creation of devices closed to an absorber. The use of these devices achieves clarity, reliability, safety, accessibility, and simplicity of the demonstration experiment.
In connection with the new technology for manufacturing glass parts and units with curved surfaces, it has become possible to implement all of the specified requirements, including the idea of ​​vertical installation of educational instruments in chemistry.
It should be noted that the instruments and devices that make up the system closed on the absorber seem to be more complex compared to conventional devices due to the introduction of new design details, but from a methodological point of view this is advisable.
The number of new structural elements is small, and they can be used in many devices for carrying out reactions with volatile substances.

END OF PARAGMEHTA BOOKS

State budgetary educational institution of secondary school No. 1 “Education Center” urban settlement. Construction ceramics of the municipal district of Volzhsky, Samara region

Subject: " Chemical experiment as a means of developing interest in chemistry"

Chemistry teacher

Lyukshina Natalia Alexandrovna

Introduction

Chemistry is a theoretical-experimental science. Therefore, in the process of studying it, the most important method is experiment as a means of obtaining specific ideas and solid knowledge.

Entertaining experiments, being part of the experiment, instill a love of chemistry, create interest in the subject in extra time from classes, contribute to more successful mastery of chemistry, deepening and expanding knowledge, developing skills for independent creative work, and instilling practical experience in working with chemical reagents and equipment.

Demonstration experiments, having an element of entertainment, contribute to the development of students’ skills in observing and explaining chemical phenomena. A chemical experiment is the most important method and the main means of visualization in the lesson. Experiment is a complex and powerful tool of knowledge. The widespread use of experiment in teaching chemistry is one of the most important conditions for students’ conscious and solid knowledge of chemistry. A chemical experiment is the most important way to connect theory with practice by transforming knowledge into beliefs.
The main goal of this report is to awaken students’ interest in chemistry from the first lessons and to show that this science is not only theoretical.

A chemical experiment based on creative independent activity helps to introduce students to the basic methods of chemical science. This occurs when the teacher often uses it in a way that resembles the inquiry process in chemical science, which works particularly well where experimentation is the basis of a problem-based approach to teaching chemistry. In these cases, experiments help confirm or reject the assumptions made, as happens in scientific research in chemistry. One of the goals of this report is to show how interesting even the most basic information from a school chemistry course can turn out to be, if only you take a closer look at it. I conducted demonstration experiments during lessons in eighth grade. As evidenced by a survey of students, the work carried out aroused interest in studying chemistry. During the experiments, schoolchildren began to think and reason logically. While carrying out this work, I realized that a chemical experiment is the core on which chemical education rests. The movement towards truth begins with surprise, and for most schoolchildren it arises precisely in the process of experimentation, when the experimenter, like a wizard, transforms one substance into another, observing amazing changes in their properties. In these cases, experiments help confirm or reject the assumptions made, as happens in scientific research in chemistry. A passion for chemistry almost always begins with experiments, and it is no coincidence that almost all famous chemists from childhood loved to experiment with substances, thanks to which many discoveries were made in chemistry, which can only be learned from history.

Throughout the history of chemistry as an experimental science, various theories have been proven or disproven, various hypotheses have been tested, new substances have been obtained and their properties have been revealed. Currently, chemical experiment is still the main tool for testing the reliability of knowledge. A chemical experiment is always carried out with a specific purpose, it is clearly planned, special conditions, necessary equipment and reagents are selected for its implementation.

Of particular importance is the question of the place of experiment in the learning process. Learning experiences are the means of learning. In one case, an experiment can be carried out after an explanation and, with its help, answer certain questions. The experiment should lead students to an understanding of the most important laws of chemistry.

In the process of teaching chemistry, an experiment is

firstly, a unique object of learning,

secondly, by research method,

thirdly, the source and means of new knowledge.

Therefore, it is characterized by three main functions:

educational, because it is important for students to master the basics of chemistry, pose and solve practical problems, and identify the importance of chemistry in modern life;

educating, because it contributes to the formation of the scientific worldview of schoolchildren, and is also important for orienting schoolchildren to relevant professions;

developing, since it serves to acquire and improve general scientific and practical skills.

Teaching chemistry at school should be visual and based on chemical experiments.

The real and virtual experiment should complement each other. A virtual chemical experiment is possible when working with toxic reagents.

Theoretical part of the experience

Chemistry is an experimental science. The Latin word "experiment" means "test", "experience". A chemical experiment is a source of knowledge about matter and chemical reactions and is an important condition for enhancing students’ cognitive activity and cultivating interest in the subject. Even the brightest image on a screen is no substitute for real-life experience, as students must observe and study the phenomena themselves.

Visualization and expressiveness of experiments is the first and main requirement for an experiment.

The short duration of the experiments is the second requirement for the experiment.

Convincingness, accessibility, reliability - this is the third requirement for an experiment.

A very important requirement is the safety of the experiments performed. In the chemistry classroom there is a stand with safety rules that must be strictly followed.

Through observation and experimentation, students learn the diverse nature of substances, accumulate facts for comparisons, generalizations, and conclusions.

From a cognitive point of view, a chemical experiment can be divided into two groups:

1. Educational experiment , which gives students knowledge about the subject being studied (for example, experiments characterizing the chemical properties of substances).

2. Visual experiment , confirming the teacher’s explanations.

Cognitive experiences can be divided into the following groups according to their meaning:

Experiments are the starting source of knowledge of the properties of substances, conditions and the mechanism of chemical reactions. Carrying out such experiments is associated with posing and solving problems of a problematic nature, and conclusions from observations act as generalizations, rules, definitions, patterns, etc.

Experiments, the cognitive value of which consists in confirming or denying the stated hypothesis. Generalized conclusions from such experiments help to solve fundamental questions about the school chemistry course, for example, the question of genetic relationships between classes of chemical compounds, etc.

Experiments illustrating conclusions and conclusions drawn from the study of theoretical principles.

Experiments that improve conclusions and consolidate students’ knowledge about the properties of substances and their transformations.

Experiments, the cognitive significance of which at a given stage is indirect in nature (examples of chemical transformations without revealing the essence of the processes).

Test experiments and experimental tasks. Their cognitive significance for students is expressed in the elements of self-control.

If an experiment is used to create problematic situations or to solve problematic problems, it should be vivid and memorable, unexpected and convincing for students, it should capture the imagination and have a strong influence on the emotional sphere. When organizing and performing a chemical experiment in this way, students delve deeply into the essence of the experiments, think about the results and try to answer questions that arise during the experiment.

A correctly conducted experiment and clear conclusions from it are the most important means of developing the scientific worldview of students.

In addition, a chemical experiment plays an important role in the successful solution of educational tasks in teaching chemistry:

As the original source of knowledge of phenomena;

As the only means of proving a hypothesis, a conclusion;

As the only means for developing the improvement of practical skills;

As an important means for developing, improving and consolidating theoretical knowledge;

As a method of testing students' knowledge and skills;

As a means of developing students’ interest in studying chemistry, developing their powers of observation, inquisitiveness, initiative, desire for independent search, improving knowledge and applying it in practice.

The school chemical experiment is of great educational importance for the polytechnic training of students.

In the practice of teaching chemistry, it is traditional to divide a chemical experiment into a demonstration experiment, carried out by a teacher, and a student experiment, performed by schoolchildren.

Demonstration experiments are a necessary type of experiment. It is used in the following cases:

when students, especially at the first stages of training, do not sufficiently master the technique of performing experiments, and therefore are not able to perform them independently;

when the technical equipment of the experience is difficult for students or there is no appropriate equipment in sufficient quantity;

when individual laboratory experiments are replaced by demonstration ones in order to save time and in case of insufficient quantities of reagents;

when the demonstration surpasses the experience performed by students in terms of external effect and persuasiveness;

when, due to safety regulations, students are prohibited from using certain substances (bromine, solid potassium permanganate, etc.).

The main requirement for any chemical experiment is the requirement that it be completely safe for students.

The teacher is responsible for the accident both morally and legally. Therefore, preliminary verification of experiments and compliance with all safety requirements are mandatory for everyone working in the chemistry room. The main guarantee of the safety of demonstration experiments is the high technical literacy of the teacher, armed with appropriate safety skills.

Student experimentation is usually divided into laboratory experiments, practical exercises, and home experiments.

The didactic purpose of laboratory experiments is to acquire new knowledge, as they are carried out while studying new material. Practical work is usually carried out at the end of studying a topic, and their goal is to consolidate and systematize knowledge, form and develop students’ experimental skills. According to the form of organization of laboratory experiments: 1) individual, 2) group, 3) collective. The results of experiments should be recorded in workbooks.

Practical classes are:

carried out according to instructions,

experimental tasks.

Practical exercises are a complex type of lesson. Students perform the experiments in pairs according to the instructions in the textbooks.

The teacher needs to monitor the entire class and correct the actions of students. After completing the experiments, each student fills out a report on the form.

Experimental problems do not contain instructions, they only have conditions. Preparation for solving experimental problems is carried out in stages. First, the problems are solved theoretically by the whole class. The student then conducts an experiment. After this, the class begins to perform similar tasks in the workplace.

A home experiment is one of the types of independent work that is of great importance both for developing interest in chemistry and for consolidating knowledge and many practical skills.

SchemeClassification of educational chemical experiment

Educational chemical experiment

Demo

Student

Laboratory experiments

Practical lessons

Workshops

Home experiments

Research

Illustrative

In addition to research work in the form of homework, there are also extracurricular research activities.

Extracurricular research activities of students can be represented by the following forms of participation of schoolchildren in them: school non-governmental educational institution; Olympiads, competition, project activities; intellectual marathons; research conferences of various types; electives, elective courses, elective courses; examination papers.

Research work is possible and effective only on a voluntary basis, like any creativity. Therefore, the topic of scientific research should be: interesting to the student, fascinating for him; feasible; original (it requires an element of surprise, unusualness); accessible; must correspond to the age characteristics of the students.

Educational and research activities contribute to: developing interest, expanding and updating knowledge on the subject, developing ideas about interdisciplinary connections; development of intellectual initiatives creating prerequisites for the development of a scientific way of thinking; mastering a creative approach to any type of activity; training in information technology and working with communications media; receiving pre-professional training; meaningful organization of children's free time. The most common form of defense of research work is the creative defense model.

The creative model of protection assumes:

Design of a stand with documents and illustrative materials on the stated topic, their commentary;

Demonstration of video recordings, slides, listening to audio recordings, presenting a fragment as the basis of a part of the study;

Conclusions on the work, made in the form of a presentation of the results;

Scientific work should be:

Research;

Current;

Have practical significance for the author himself and the school.

Creative discoveries and methodological achievements of the teacher

The role of chemistry in solving environmental problems is enormous. In my work I use active learning methods: non-traditional lessons, elective courses, environmental projects, seminars, conferences. The greening of a chemical experiment involves experimental testing of the purity of food products and serves as the basis for creating problematic situations.

2010-2011 academic year

In 2010, I received a certificate of winner of 1st place in the regional scientific and practical conference from the Municipal Educational Institution of Educational Institution TsVR of the Volzhsky municipal district of the Samara region in the 11th grade