What is in salts. Salt. Names and classification of salts
Metal nitrites in the +2 oxidation state form crystal hydrates with one, two or four water molecules. Nitrites form double and triple salts, for example. CsNO2. AgNO 2 or Ba(NO 2) 2 . Ni(NO2)2. 2KNO 2 , as well as complex compounds, such as Na 3 .
Crystal structures are known only for a few anhydrous nitrites. The NO2 anion has a nonlinear configuration; ONO angle 115°, H–O bond length 0.115 nm; the type of bond M—NO 2 is ionic-covalent.
K, Na, Ba nitrites are well soluble in water, Ag, Hg, Cu nitrites are poorly soluble. With increasing temperature, the solubility of nitrites increases. Almost all nitrites are poorly soluble in alcohols, ethers, and low-polarity solvents.
Nitrites are thermally unstable; melt without decomposition only nitrites of alkali metals, nitrites of other metals decompose at 25-300 °C. The mechanism of nitrite decomposition is complex and includes a number of parallel-sequential reactions. The main gaseous decomposition products are NO, NO 2, N 2 and O 2, solid ones are metal oxide or elemental metal. The release of a large amount of gases causes the explosive decomposition of some nitrites, for example NH 4 NO 2, which decomposes into N 2 and H 2 O.
The characteristic features of nitrites are associated with their thermal instability and the ability of the nitrite ion to be both an oxidizing agent and a reducing agent, depending on the medium and the nature of the reagents. In a neutral environment, nitrites are usually reduced to NO, in an acidic environment they are oxidized to nitrates. Oxygen and CO 2 do not interact with solid nitrites and their aqueous solutions. Nitrites contribute to the decomposition of nitrogen-containing organic matter, in particular amines, amides, etc. With organic halides RXH. react to form both RONO nitrites and RNO 2 nitro compounds.
The industrial production of nitrites is based on the absorption of nitrous gas (a mixture of NO + NO 2) with solutions of Na 2 CO 3 or NaOH with successive crystallization of NaNO 2; nitrites of other metals in industry and laboratories are obtained by the exchange reaction of metal salts with NaNO 2 or by the reduction of nitrates of these metals.
Nitrites are used for the synthesis of azo dyes, in the production of caprolactam, as oxidizing and reducing agents in the rubber, textile and metalworking industries, as food preservatives. Nitrites such as NaNO 2 and KNO 2 are toxic, cause headache, vomiting, depress breathing, etc. When NaNO 2 is poisoned, methemoglobin is formed in the blood, erythrocyte membranes are damaged. Perhaps the formation of nitrosamines from NaNO 2 and amines directly in the gastrointestinal tract.
6. Sulfates, salts of sulfuric acid. Medium sulfates with the anion SO 4 2- are known, acidic, or hydrosulfates, with the anion HSO 4 -, basic, containing along with the anion SO 4 2- - OH groups, for example Zn 2 (OH) 2 SO 4. There are also double sulfates, which include two different cations. These include two large groups of sulfates - alum, as well as chenites M 2 E (SO 4) 2. 6H 2 O, where M is a singly charged cation, E is Mg, Zn and other doubly charged cations. Known triple sulfate K 2 SO 4 . MgSO4. 2CaSO4. 2H 2 O (mineral polyhalite), double basic sulfates, such as minerals of the alunite and jarosite groups M 2 SO 4 . Al 2 (SO 4) 3 . 4Al (OH 3 and M 2 SO 4. Fe 2 (SO 4) 3. 4Fe (OH) 3, where M is a singly charged cation. Sulfates can be part of mixed salts, for example. 2Na 2 SO 4. Na 2 CO 3 ( mineral berkeite), MgSO 4. KCl. 3H 2 O (kainite).
Sulfates are crystalline substances, medium and acidic, in most cases they are highly soluble in water. Slightly soluble sulfates of calcium, strontium, lead and some others, practically insoluble BaSO 4 , RaSO 4 . Basic sulfates are usually sparingly soluble or practically insoluble, or hydrolyzed by water. Sulfates can crystallize from aqueous solutions in the form of crystalline hydrates. The crystalline hydrates of some heavy metals are called vitriol; copper sulphate СuSO 4. 5H 2 O, ferrous sulfate FeSO 4. 7H 2 O.
Medium alkali metal sulfates are thermally stable, while acid sulfates decompose when heated, turning into pyrosulfates: 2KHSO 4 \u003d H 2 O + K 2 S 2 O 7. Average sulfates of other metals, as well as basic sulfates, when heated to sufficiently high temperatures, as a rule, decompose with the formation of metal oxides and the release of SO 3 .
Sulfates are widely distributed in nature. They occur as minerals, such as gypsum CaSO 4 . H 2 O, mirabilite Na 2 SO 4. 10H 2 O, and are also part of sea and river water.
Many sulfates can be obtained by the interaction of H 2 SO 4 with metals, their oxides and hydroxides, as well as by the decomposition of salts of volatile acids with sulfuric acid.
Inorganic sulfates are widely used. For example, ammonium sulfate is a nitrogen fertilizer, sodium sulfate is used in the glass, paper industry, viscose production, etc. Natural sulfate minerals are raw materials for the industrial production of compounds of various metals, building materials, etc.
7. Sulfites, salts of sulfurous acid H 2 SO 3. There are medium sulfites with the anion SO 3 2- and acidic (hydrosulfites) with the anion HSO 3 -. Medium sulfites are crystalline substances. Ammonium and alkali metal sulfites are highly soluble in water; solubility (g in 100 g): (NH 4) 2 SO 3 40.0 (13 ° C), K 2 SO 3 106.7 (20 ° C). In aqueous solutions they form hydrosulfites. Sulfites of alkaline earth and some other metals are practically insoluble in water; solubility of MgSO 3 1 g in 100 g (40°C). Crystal hydrates (NH 4) 2 SO 3 are known. H 2 O, Na 2 SO 3. 7H 2 O, K 2 SO 3. 2H 2 O, MgSO 3. 6H 2 O, etc.
Anhydrous sulfites, when heated without access to air in sealed vessels, disproportionate into sulfides and sulfates, when heated in a stream of N 2 they lose SO 2, and when heated in air, they are easily oxidized to sulfates. From SO 2 to aquatic environment medium sulfites form hydrosulfites. Sulfites are relatively strong reducing agents; they are oxidized in solutions with chlorine, bromine, H 2 O 2, etc. to sulfates. They are decomposed by strong acids (for example, HC1) with the release of SO 2.
Crystalline hydrosulfites are known for K, Rb, Cs, NH 4 +, they are unstable. Other hydrosulfites exist only in aqueous solutions. Density NH 4 HSO 3 2.03 g/cm3; solubility in water (g per 100 g): NH 4 HSO 3 71.8 (0 ° C), KHSO 3 49 (20 ° C).
When crystalline hydrosulfites Na or K are heated, or when the slurry solution of the pulp M 2 SO 3 is saturated with SO 2, pyrosulfites (obsolete - metabisulfites) M 2 S 2 O 5 are formed - salts of pyrosulfurous acid unknown in the free state H 2 S 2 O 5; crystals, unstable; density (g/cm3): Na 2 S 2 O 5 1.48, K 2 S 2 O 5 2.34; above ~ 160 °С they decompose with the release of SO 2; dissolve in water (with decomposition to HSO 3 -), solubility (g per 100 g): Na 2 S2O 5 64.4, K 2 S 2 O 5 44.7; form Na 2 S 2 O 5 hydrates. 7H 2 O and ZK 2 S 2 O 5 . 2H 2 O; reducing agents.
Medium alkali metal sulfites are obtained by reacting an aqueous solution of M 2 CO 3 (or MOH) with SO 2 , and MSO 3 by passing SO 2 through an aqueous suspension of MCO 3 ; mainly SO 2 is used from the off-gases of contact sulfuric acid production. Sulfites are used in bleaching, dyeing and printing of fabrics, fibers, leather for grain conservation, green fodder, industrial feed waste (NaHSO 3 ,Na 2 S 2 O 5). CaSO 3 and Ca(HSO 3) 2 - disinfectants in winemaking and sugar industry. NaНSO 3 , MgSO 3 , NH 4 НSO 3 - components of sulfite liquor during pulping; (NH 4) 2SO 3 - SO 2 absorber; NaHSO 3 is an H 2 S absorber from production waste gases, a reducing agent in the production of sulfur dyes. K 2 S 2 O 5 - component of acid fixers in photography, antioxidant, antiseptic.
Food salt is essentially a universal product, a mineral that has been accompanying a person since ancient times. A long time ago, people realized the importance of this seasoning in their lives, which is why there are a number of proverbs and sayings, for example, “Eat a pound of salt with someone” or “Leave without salted bread” and of course many others, reflecting the great respect of the people for this product . And edible salt very often in many civilizations was used as a bargaining chip, for a certain small amount of which you could even buy yourself a slave.
The process of extracting table salt is not much different in our time from the ancient methods. Moreover, the extraction of certain species is carried out in almost every country. The production of edible salt is different, most often carried out in the following three ways:
- Salt is self-planting, which is formed by the natural evaporation of sea water.
- Self-planting salt obtained from the bottom of salt lakes, or in salt cave reservoirs.
- Rock edible salt obtained from the development of mines. Such salt is not subjected to any heat treatment during extraction.
The chemical composition of edible salt
The chemical composition of edible salt according to GOST is actually very simple. It is a compound formed by the interaction of an alkali and an acid, two chemical elements- sodium and chlorine. Therefore, the formula of edible salt is NaCl. This compound is obtained in the form of white crystals (see photo), which we are used to seeing in our salt shakers.
Benefits of edible salt
The benefits of this product are very unlikely to be underestimated in a person's life. Nowadays, the variety of different types of salt on the shelves of shops and supermarkets is incredibly wide. You can see sea, and iodized, and Himalayan, and pink with black, and many other species. All of them differ in the place of extraction, cleaning methods and many other factors that affect the presence of additional useful ingredients in the composition of the salt.
Thanks to all this, this product has a huge number of useful properties. Every day, about five grams of this mineral must enter our body to maintain water balance. It also serves as the basis for the formation of hydrochloric acid in the stomach, which perform the lion's share of the digestive process. This mineral must be present in the blood and liver of a person, and even on cellular level. Thanks to his unique composition It helps to maintain proper electrolyte levels.
Application in cooking
The use of edible salt as an additive in cooking is used all over the world. There is not a single cuisine in the world where this seasoning would not be used. In addition to adding flavor, it is also used as a preservative for the long-term preservation of vegetables, meat, and fish. It is important to remember that it should be used in moderation.
Useful properties and use in treatment
The beneficial properties of edible salt and the use of this composition in the treatment have been known since ancient times and are confirmed by modern research. Sodium chloride, this is exactly what the compound is called, due to its indispensability in biological processes, both human and the rest of the plant and animal world, plays an important role in the life of every organism.
Sodium is, in fact, the main cation involved in maintaining the required level of acid-base balance, moreover, it is he who is responsible for the constancy of osmotic pressure.
The sodium-potassium compound ensures the penetration of glucose and amino acids through the cell membrane. With the insufficiency of this component in the human body, the transmission of nerve impulses and the activity of various muscles, including the heart, will not be able to function properly.
Without sodium, it will be quite difficult for the colon to absorb certain nutrients.
Chlorine is responsible for the formation of hydrochloric acid and some other substances in the body responsible for the breakdown of fats. It is the main stimulant of sexual and nervous systems, and with its insufficient presence in the body, the full formation of bone and muscle tissues is impossible.
The use of salt to benefit the body is possible not only with the help of its ingestion. We can greatly improve our health by applying some topical sodium chloride recipes.
For example, salt baths are very popular to strengthen the nail plate. To get it, dissolve a few tablespoons in a cup of water and dip your fingertips in it for a few minutes.
Also, with a runny nose, it is advised to do such a warm-up: heat a glass of salt in a frying pan, pour it into a bag of gauze or canvas, and warm the bridge of the nose.
Even in the fight against excess weight, extra food salt will become a faithful assistant. Dissolve two kilograms of salt in a bath of hot water and plunge into the resulting solution for fifteen minutes.
In addition to these, there are many other ways to use this product for the benefit of your own body.
Harm of salt and contraindications
There are many theories about the harm of this product. The most important thing that all researchers note is not to overdo it in use. Fifteen grams of sodium chloride per day is considered the optimal norm for a healthy adult. And it should be counted as such. Ten grams enters the body already in the composition of consumed products. And only five grams can be consumed additionally when preparing various dishes.
Extra food salt can in large quantities lead to clogging of the cells of our body with various harmful substances, can cause tissue edema and additional stress on arterial vessels and the heart. It should be borne in mind that excessive consumption of this product can lead to complications in the work of the whole organism. In addition, the nutritional value of edible salt is also quite high, and an excessive amount of salt in the body leads to additional stagnation of water in the body.
Therefore, it is worth being moderate in salting dishes, and, if possible, avoid additional intakes of this mineral, because the benefits and harms of edible salt will always depend only on your prudence. And then this ancient flavoring product will serve only for the benefit of your health.
In order to answer the question of what salt is, you usually don’t have to think for a long time. This chemical compound is Everyday life occurs quite often. There is no need to talk about ordinary table salt. Detailed internal structure salts and their compounds are studied by inorganic chemistry.
Salt definition
A clear answer to the question of what salt is can be found in the works of M. V. Lomonosov. He gave this name to fragile bodies that can dissolve in water and do not ignite under the influence of high temperatures or open flames. Later, the definition was derived not from their physical, but from the chemical properties of these substances.
School textbooks of inorganic chemistry give a fairly clear concept of what salt is. What are substitution products called? chemical reaction, at which the hydrogen atoms of the acid in the compound are replaced by a metal. Examples of typical salt compounds: NaCL, MgSO 4 . It is easy to see that any of this entry can be divided into two halves: the metal will always be written in the left component of the formula, and the acid residue will always be written in the right. The standard salt formula is as follows:
Me n m Acid residue m n .
Physical properties of salt
Chemistry, as an exact science, puts in the name of a substance all possible information about its composition and capabilities. So, all the names of salts in the modern interpretation consist of two words: one part has the name of the metal component in the nominative case, the second contains a description of the acid residue.
These compounds do not have a molecular structure, therefore, under normal conditions, they are solid crystalline substances. Many salts have crystal lattice. The crystals of these substances are refractory, so very high temperatures are needed to melt them. For example, barium sulfide melts at about 2200°C.
According to the solubility of salts are divided into soluble, sparingly soluble and insoluble. Examples of the former are sodium chloride, potassium nitrate. Slightly soluble include magnesium sulfite, lead chloride. Insoluble is calcium carbonate. Information on the solubility of a particular substance is contained in the reference literature.
The chemical reaction product in question is usually odorless and has a variable taste. The assumption that all salts are salty is wrong. Pure salty taste has only one element of this class - our old familiar table salt. There are sweet salts of beryllium, bitter - magnesium and tasteless - for example, calcium carbonate (ordinary chalk).
Most of these substances are colorless, but among them there are those that have characteristic colors. For example, iron (II) sulfate has a characteristic green color, potassium permanganate is purple, and potassium chromate crystals are bright yellow.
Salt classification
Chemistry divides all types of inorganic salts into several main features. Salts resulting from the complete replacement of hydrogen in an acid are called normal or average. For example, calcium sulfate.
Salt, which is a derivative of an incomplete substitution reaction, is called acidic or basic. An example of such formation can be the reaction of potassium hydrogen sulfate:
The basic salt is obtained by such a reaction in which the hydroxo group is not completely replaced by an acid residue. Substances of this type can be formed by those metals whose valency is two or more. A typical salt formula of this group can be derived from this reaction:
Normal, medium and acidic chemical compounds form classes of salts and are the standard classification of these compounds.
Double and mixed salt
An example of a mixed one is the calcium salt of hydrochloric and hypochlorous acid: CaOCl 2.
Nomenclature
Salts formed by metals with variable valency have an additional designation: after the formula, the valency is written in brackets in Roman numerals. So, there is iron sulfate FeSO 4 (II) and Fe 2 (SO4) 3 (III). In the name of salts there is a prefix hydro-, if there are unsubstituted hydrogen atoms in its composition. For example, potassium hydrogen phosphate has the formula K 2 HPO 4 .
Properties of salts in electrolytes
The theory of electrolytic dissociation gives its own interpretation of chemical properties. In the light of this theory, a salt can be defined as a weak electrolyte that, when dissolved, dissociates (breaks down) in water. Thus, a salt solution can be represented as a complex of positive negative ions, and the first ones are not H + hydrogen atoms, and the second ones are not OH - hydroxo group atoms. There are no ions that would be present in all types of salt solutions, so any common properties they don't possess. The lower the charges of the ions that form the salt solution, the better they dissociate, the better the electrical conductivity of such a liquid mixture.
Acid salt solutions
Acid salts in solution decompose into complex negative ions, which are an acid residue, and simple anions, which are positively charged metal particles.
For example, the dissolution reaction of sodium bicarbonate leads to the decomposition of the salt into sodium ions and the rest of HCO 3 -.
Full formula looks like this: NaHCO 3 = Na + + HCO 3 -, HCO 3 - = H + + CO 3 2-.
Solutions of basic salts
The dissociation of basic salts leads to the formation of acid anions and complex cations consisting of metals and hydroxogroups. These complex cations, in turn, are also able to decompose in the process of dissociation. Therefore, in any solution of a salt of the main group, there are OH - ions. For example, the dissociation of hydroxomagnesium chloride proceeds as follows:
Distribution of salts
What is salt? This element is one of the most common chemical compounds. Everyone knows table salt, chalk (calcium carbonate) and so on. Among the carbonate salts, the most common is calcium carbonate. It is an integral part of marble, limestone, dolomite. And calcium carbonate is the basis for the formation of pearls and corals. This chemical compound is essential for the formation of hard integuments in insects and skeletons in chordates.
Salt has been known to us since childhood. Doctors warn against its excessive use, but in moderation it is essential for the implementation of vital processes in the body. And it is needed to maintain the correct composition of the blood and the production of gastric juice. Saline solutions, an integral part of injections and droppers, are nothing more than a solution of table salt.
Definition salts within the framework of the theory of dissociation. Salts are usually divided into three groups: medium, sour and basic. In medium salts, all hydrogen atoms of the corresponding acid are replaced by metal atoms, in acid salts they are only partially replaced, in basic salts of the OH group of the corresponding base they are partially replaced by acid residues.
There are also some other types of salts, such as double salts, which contain two different cations and one anion: CaCO 3 MgCO 3 (dolomite), KCl NaCl (sylvinite), KAl (SO 4) 2 (potassium alum); mixed salts, which contain one cation and two different anions: CaOCl 2 (or Ca(OCl)Cl); complex salts, which include complex ion, consisting of a central atom linked to several ligands: K 4 (yellow blood salt), K 3 (red blood salt), Na, Cl; hydrated salts(crystal hydrates), which contain molecules water of crystallization: CuSO 4 5H 2 O (copper sulfate), Na 2 SO 4 10H 2 O (Glauber's salt).
The name of the salts is formed from the name of the anion followed by the name of the cation.
For salts of oxygen-free acids, a suffix is added to the name of the non-metal id, e.g. sodium chloride NaCl, iron(H) sulfide FeS, etc.
When naming salts of oxygen-containing acids, the Latin root of the name of the element is added in case higher degrees oxidation ending — am, in the case of lower oxidation states, the ending -it. In the names of some acids, the prefix is used to designate the lowest oxidation states of a non-metal hypo-, for salts of perchloric and permanganic acids, use the prefix per-, ex: calcium carbonate CaCO 3, iron (III) sulfate Fe 2 (SO 4) 3, iron (II) sulfite FeSO 3, potassium hypochlorite KOSl, potassium chlorite KOSl 2, potassium chlorate KOSl 3, potassium perchlorate KOSl 4, potassium permanganate KMnO 4, potassium dichromate K 2 Cr 2 O 7 .
Acid and basic salts can be considered as a product of incomplete conversion of acids and bases. According to the international nomenclature, the hydrogen atom, which is part of the acid salt, is denoted by the prefix hydro-, OH group - prefix hydroxy, NaHS - sodium hydrosulfide, NaHSO 3 - sodium hydrosulfite, Mg (OH) Cl - magnesium hydroxychloride, Al (OH) 2 Cl - aluminum dihydroxy chloride.
In the names of complex ions, ligands are first indicated, followed by the name of the metal, indicating the corresponding oxidation state (Roman numerals in brackets). In the names of complex cations, Russian names of metals are used, for example: Cl 2 - tetraammine copper (P) chloride, 2 SO 4 - diammine silver (1) sulfate. In the names of complex anions, the Latin names of metals with the suffix -at are used, for example: K[Al(OH) 4 ] - potassium tetrahydroxyaluminate, Na - sodium tetrahydroxychromate, K 4 - potassium hexacyanoferrate (H) .
Names of hydrated salts (crystalline hydrates) are formed in two ways. You can use the complex cation naming system described above; for example, copper sulfate SO 4 H 2 0 (or CuSO 4 5H 2 O) can be called tetraaquacopper(II) sulfate. However, for the most well-known hydrated salts, most often the number of water molecules (the degree of hydration) is indicated by a numerical prefix to the word "hydrate", for example: CuSO 4 5H 2 O - copper (I) sulfate pentahydrate, Na 2 SO 4 10H 2 O - sodium sulfate decahydrate, CaCl 2 2H 2 O - calcium chloride dihydrate.
Solubility of salts
According to their solubility in water, salts are divided into soluble (P), insoluble (H) and slightly soluble (M). To determine the solubility of salts, use the table of the solubility of acids, bases and salts in water. If there is no table at hand, then you can use the rules. They are easy to remember.
1. All salts of nitric acid are soluble - nitrates.
2. All salts of hydrochloric acid are soluble - chlorides, except for AgCl (H), PbCl 2 (M).
3. All salts of sulfuric acid - sulfates are soluble, except for BaSO 4 (H), PbSO 4 (H).
4. Sodium and potassium salts are soluble.
5. All phosphates, carbonates, silicates and sulfides do not dissolve, except for Na salts + and K + .
Of all chemical compounds, salts are the most numerous class of substances. These are solids, they differ from each other in color and solubility in water. IN early XIX V. Swedish chemist I. Berzelius formulated the definition of salts as reaction products of acids with bases or compounds obtained by replacing hydrogen atoms in an acid with a metal. On this basis, salts are distinguished as medium, acidic and basic. Medium, or normal, salts are products of the complete replacement of hydrogen atoms in an acid with a metal.
For example:
Na 2 CO 3 - sodium carbonate;
CuSO 4 - copper (II) sulfate, etc.
Such salts dissociate into metal cations and anions of the acid residue:
Na 2 CO 3 \u003d 2Na + + CO 2 -
Acid salts are products of incomplete replacement of hydrogen atoms in an acid by a metal. Acid salts include, for example, baking soda NaHCO 3 , which consists of a metal cation Na + and an acidic singly charged residue HCO 3 - . For an acidic calcium salt, the formula is written as follows: Ca (HCO 3) 2. The names of these salts are made up of the names of medium salts with the addition of the prefix hydro- , For example:
Mg (HSO 4) 2 - magnesium hydrosulfate.
Dissociate acid salts as follows:
NaHCO 3 \u003d Na + + HCO 3 -
Mg (HSO 4) 2 \u003d Mg 2+ + 2HSO 4 -
Basic salts are products of incomplete substitution of hydroxo groups in the base for an acid residue. For example, such salts include the famous malachite (CuOH) 2 CO 3, which you read about in the works of P. Bazhov. It consists of two basic cations CuOH + and a doubly charged anion of the acid residue CO 3 2- . The CuOH + cation has a +1 charge, therefore, in the molecule, two such cations and one doubly charged CO 3 2- anion are combined into an electrically neutral salt.
The names of such salts will be the same as for normal salts, but with the addition of the prefix hydroxo-, (CuOH) 2 CO 3 - copper (II) hydroxocarbonate or AlOHCl 2 - aluminum hydroxochloride. Most basic salts are insoluble or sparingly soluble.
The latter dissociate like this:
AlOHCl 2 \u003d AlOH 2 + + 2Cl -
Salt properties
The first two exchange reactions have been discussed in detail previously.
The third reaction is also an exchange reaction. It flows between salt solutions and is accompanied by the formation of a precipitate, for example:
The fourth reaction of salts is associated with the position of the metal in the electrochemical series of metal voltages (see "Electrochemical series of metal voltages"). Each metal displaces from salt solutions all other metals located to the right of it in a series of voltages. This is subject to the following conditions:
1) both salts (both reacting and formed as a result of the reaction) must be soluble;
2) metals should not interact with water, therefore, metals of the main subgroups of groups I and II (for the latter, starting with Ca) do not displace other metals from salt solutions.
Methods for obtaining salts
Ways to get and Chemical properties salts. Salts can be obtained from inorganic compounds of almost any class. Along with these methods, salts of anoxic acids can be obtained by direct interaction of a metal and a non-metal (Cl, S, etc.).
Many salts are stable when heated. However, ammonium salts, as well as some salts of low-active metals, weak acids and acids in which elements exhibit higher or lower oxidation states, decompose when heated.
CaCO 3 \u003d CaO + CO 2
2Ag 2 CO 3 \u003d 4Ag + 2CO 2 + O 2
NH 4 Cl \u003d NH 3 + HCl
2KNO 3 \u003d 2KNO 2 + O 2
2FeSO 4 \u003d Fe 2 O 3 + SO 2 + SO 3
4FeSO 4 \u003d 2Fe 2 O 3 + 4SO 2 + O 2
2Cu(NO 3) 2 \u003d 2CuO + 4NO 2 + O 2
2AgNO 3 \u003d 2Ag + 2NO 2 + O 2
NH 4 NO 3 \u003d N 2 O + 2H 2 O
(NH 4) 2 Cr 2 O 7 \u003d Cr 2 O 3 + N 2 + 4H 2 O
2KSlO 3 \u003d MnO 2 \u003d 2KCl + 3O 2
4KClO 3 \u003d 3KSlO 4 + KCl
