A salt can be defined as a compound that is formed by the reaction between an acid and a base, but is not water. In this section, those properties of salts that are associated with ionic equilibria will be considered.
salt reactions in water
Somewhat later it will be shown that solubility is a relative concept. However, for the purposes of the following discussion, we can roughly classify all salts into water-soluble and water-insoluble salts.
Some salts, when dissolved in water, form neutral solutions. Other salts form acidic or alkaline solutions. This is due to the occurrence of a reversible reaction between salt ions and water, as a result of which conjugate acids or bases are formed. Whether a salt solution is neutral, acidic, or alkaline depends on the type of salt. In this sense, there are four types of salts.
Salts formed by strong acids and weak bases. Salts of this type, when dissolved in water, form an acidic solution. Let's take ammonium chloride NH4Cl as an example. When this salt is dissolved in water, the ammonium ion acts as
The excess amount of H3O+ ions formed in this process determines the acidic properties of the solution.
Salts formed by a weak acid and a strong base. Salts of this type, when dissolved in water, form an alkaline solution. As an example, let's take sodium acetate CH3COONa1 The acetate ion acts as a base, accepting a proton from water, which in this case acts as an acid:
An excess of OH- ions formed in this process determines the alkaline properties of the solution.
Salts formed by strong acids and strong bases. When salts of this type are dissolved in water, a neutral solution is formed. Let's take sodium chloride NaCl as an example. When dissolved in water, this salt is completely ionized, and, therefore, the concentration of Na+ ions is equal to the concentration of Cl- ions. Since neither ion enters into acid-base reactions with water, there is no formation of an excess amount of H3O + or OH ions in the solution. Therefore, the solution is neutral.
Salts formed by weak acids and weak bases. An example of salts of this type is ammonium acetate. When dissolved in water, the ammonium ion reacts with water as an acid, and the acetate ion reacts with water as a base. Both of these reactions are described above. An aqueous solution of a salt formed by a weak acid and a weak base can be weakly acidic, slightly alkaline, or neutral, depending on the relative concentrations of H3O+ and OH- ions formed as a result of the reactions of cations and anions of the salt with water. It depends on the ratio between the values of the dissociation constants of the cation and anion.
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, in the case of higher oxidation states, the ending is added to the Latin root of the name of the element — 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. At the beginning of the XIX century. 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
Methods for obtaining and chemical properties of 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
The solubility table of salts, acids and bases is the foundation, without which it is impossible to fully master chemical knowledge. The solubility of bases and salts helps in teaching not only schoolchildren, but also professional people. The creation of many life products cannot do without this knowledge.
Table of solubility of acids, salts and bases in water
The table of solubility of salts and bases in water is a manual that helps in mastering the basics of chemistry. The following notes will help you understand the table below.
- P - indicates a soluble substance;
- H is an insoluble substance;
- M - the substance is slightly soluble in the aquatic environment;
- RK - a substance can dissolve only when exposed to strong organic acids;
- The dash will say that such a creature does not exist in nature;
- NK - does not dissolve in either acids or water;
- ? - a question mark indicates that today there is no exact information about the dissolution of the substance.
Often, the table is used by chemists and schoolchildren, students for laboratory research, during which it is necessary to establish the conditions for the occurrence of certain reactions. According to the table, it turns out to find out how the substance behaves in a hydrochloric or acidic environment, whether a precipitate is possible. Precipitate during research and experiments indicates the irreversibility of the reaction. This is a significant point that can affect the course of the entire laboratory work.
Table salt is sodium chloride used as a food additive and food preservative. It is also used in the chemical industry, medicine. It serves as the most important raw material for the production of caustic soda, soda and other substances. The formula for table salt is NaCl.
Formation of an ionic bond between sodium and chlorine
The chemical composition of sodium chloride reflects the conditional formula NaCl, which gives an idea of the equal number of sodium and chlorine atoms. But the substance is formed not by diatomic molecules, but consists of crystals. When an alkali metal interacts with a strong non-metal, each sodium atom gives off more electronegative chlorine. There are sodium cations Na + and anions of the acid residue of hydrochloric acid Cl - . Oppositely charged particles are attracted, forming a substance with an ionic crystal lattice. Small sodium cations are located between large chloride anions. The number of positive particles in the composition of sodium chloride is equal to the number of negative ones, the substance as a whole is neutral.
Chemical formula. Table salt and halite
Salts are complex ionic substances whose names begin with the name of the acid residue. The formula for table salt is NaCl. Geologists call a mineral of this composition “halite”, and sedimentary rock is called “rock salt”. An obsolete chemical term that is often used in industry is "sodium chloride". This substance has been known to people since ancient times, it was once considered "white gold". Modern schoolchildren and students, when reading the equations of reactions involving sodium chloride, call chemical signs ("sodium chloride").
We will carry out simple calculations according to the formula of the substance:
1) Mr (NaCl) \u003d Ar (Na) + Ar (Cl) \u003d 22.99 + 35.45 \u003d 58.44.
The relative is 58.44 (in amu).
2) The molar mass is numerically equal to the molecular weight, but this value has units of g / mol: M (NaCl) \u003d 58.44 g / mol.
3) A 100 g sample of salt contains 60.663 g of chlorine atoms and 39.337 g of sodium.
Physical properties of table salt
Brittle crystals of halite are colorless or white. In nature, there are also deposits of rock salt, painted in gray, yellow or blue. Sometimes the mineral substance has a red tint, which is due to the types and amount of impurities. The hardness of halite is only 2-2.5, the glass leaves a line on its surface.
Other physical parameters of sodium chloride:
- smell - absent;
- taste - salty;
- density - 2.165 g / cm3 (20 ° C);
- melting point - 801 ° C;
- boiling point - 1413 ° C;
- solubility in water - 359 g / l (25 ° C);
Obtaining sodium chloride in the laboratory
When metallic sodium interacts with gaseous chlorine in a test tube, a white substance is formed - sodium chloride NaCl (common salt formula).
Chemistry gives an idea of the different ways to obtain the same compound. Here are some examples:
NaOH (aq.) + HCl \u003d NaCl + H 2 O.
Redox reaction between metal and acid:
2Na + 2HCl \u003d 2NaCl + H 2.
Action of acid on metal oxide: Na 2 O + 2HCl (aq.) = 2NaCl + H 2 O
Displacement of a weak acid from a solution of its salt by a stronger one:
Na 2 CO 3 + 2HCl (aq.) \u003d 2NaCl + H 2 O + CO 2 (gas).
All of these methods are too expensive and complicated to be applied on an industrial scale.
Salt production
Even at the dawn of civilization, people knew that after salting, meat and fish last longer. Transparent, regular-shaped halite crystals were used in some ancient countries instead of money and were worth their weight in gold. The search and development of halite deposits made it possible to meet the growing needs of the population and industry. The most important natural sources of table salt:
- deposits of the mineral halite in different countries;
- water of the seas, oceans and salt lakes;
- layers and crusts of rock salt on the banks of salt water bodies;
- halite crystals on the walls of volcanic craters;
- salt marshes.
In industry, four main methods of obtaining table salt are used:
- leaching of halite from the underground layer, evaporation of the resulting brine;
- mining in ;
- evaporation or brine of salt lakes (77% of the mass of dry residue is sodium chloride);
- use of a by-product of desalination of salt water.
Chemical properties of sodium chloride
In its composition, NaCl is a medium salt formed by an alkali and a soluble acid. Sodium chloride is a strong electrolyte. The attraction between ions is so strong that only highly polar solvents can destroy it. In water, substances decompose, cations and anions (Na +, Cl -) are released. Their presence is due to the electrical conductivity, which has a solution of common salt. The formula in this case is written in the same way as for dry matter - NaCl. One of the qualitative reactions to the sodium cation is the yellow coloring of the burner flame. To obtain the result of the experiment, you need to collect a little solid salt on a clean wire loop and add it to the middle part of the flame. The properties of table salt are also associated with the feature of the anion, which consists in a qualitative reaction to the chloride ion. When interacting with silver nitrate in solution, a white precipitate of silver chloride precipitates (photo). Hydrogen chloride is displaced from the salt by stronger acids than hydrochloric: 2NaCl + H 2 SO 4 = Na 2 SO 4 + 2HCl. Under normal conditions, sodium chloride does not undergo hydrolysis.
Areas of application of rock salt
Sodium chloride lowers the melting point of ice, which is why a mixture of salt and sand is used on roads and sidewalks in winter. It absorbs a large amount of impurities, while thawing pollutes rivers and streams. Road salt also accelerates the corrosion process of car bodies and damages trees planted next to roads. In the chemical industry, sodium chloride is used as a raw material for the production of a large group of chemicals:
- of hydrochloric acid;
- metallic sodium;
- gaseous chlorine;
- caustic soda and other compounds.
In addition, table salt is used in the manufacture of soaps and dyes. As a food antiseptic, it is used in canning, pickling mushrooms, fish and vegetables. To combat thyroid disorders in the population, the table salt formula is enriched by adding safe iodine compounds, for example, KIO 3 , KI, NaI. Such supplements support the production of thyroid hormone, prevent the disease of endemic goiter.
The value of sodium chloride for the human body
The formula of table salt, its composition has become vital for human health. Sodium ions are involved in the transmission of nerve impulses. Chlorine anions are necessary for the production of hydrochloric acid in the stomach. But too much salt in food can lead to high blood pressure and increase the risk of developing heart and vascular diseases. In medicine, with a large blood loss, patients are injected with physiological saline. To obtain it, 9 g of sodium chloride is dissolved in one liter of distilled water. The human body needs a continuous supply of this substance with food. Salt is excreted through the excretory organs and skin. The average content of sodium chloride in the human body is approximately 200 g. Europeans consume about 2-6 g of table salt per day, in hot countries this figure is higher due to higher sweating.
SALT, a class of chemical compounds. A generally accepted definition of the concept of “Salts”, as well as the terms “acids and bases”, the products of the interaction of which salts are, currently does not exist. Salts can be considered as products of substitution of acid hydrogen protons for metal ions, NH 4 + , CH 3 NH 3 + and other cations or base OH groups for acid anions (eg, Cl - , SO 4 2-).
Classification
The products of complete substitution are medium salts, for example. Na 2 SO 4 , MgCl 2 , partially acidic or basic salts, for example KHSO 4 , СuСlOH. There are also simple salts, including one type of cations and one type of anions (for example, NaCl), double salts containing two types of cations (for example, KAl (SO 4) 2 12H 2 O), mixed salts, which include two types of acid residues ( e.g. AgClBr). Complex salts contain complex ions such as K 4 .
Physical properties
Typical salts are crystalline substances with an ionic structure, such as CsF. There are also covalent salts, such as AlCl 3 . In fact, the nature of the chemical bond v of many salts is mixed.
By solubility in water, soluble, slightly soluble and practically insoluble salts are distinguished. Soluble include almost all salts of sodium, potassium and ammonium, many nitrates, acetates and chlorides, with the exception of salts of polyvalent metals that hydrolyze in water, many acidic salts.
Solubility of salts in water at room temperature
| Cations | anions | |||||||||
| F- | Cl- | br- | I- | S2- | NO 3 - | CO 3 2- | SiO 3 2- | SO 4 2- | PO 4 3- | |
| Na+ | R | R | R | R | R | R | R | R | R | R |
| K+ | R | R | R | R | R | R | R | R | R | R |
| NH4+ | R | R | R | R | R | R | R | R | R | R |
| Mg2+ | RK | R | R | R | M | R | H | RK | R | RK |
| Ca2+ | NK | R | R | R | M | R | H | RK | M | RK |
| Sr2+ | NK | R | R | R | R | R | H | RK | RK | RK |
| Ba 2+ | RK | R | R | R | R | R | H | RK | NK | RK |
| sn 2+ | R | R | R | M | RK | R | H | H | R | H |
| Pb 2+ | H | M | M | M | RK | R | H | H | H | H |
| Al 3+ | M | R | R | R | G | R | G | NK | R | RK |
| Cr3+ | R | R | R | R | G | R | G | H | R | RK |
| Mn2+ | R | R | R | R | H | R | H | H | R | H |
| Fe2+ | M | R | R | R | H | R | H | H | R | H |
| Fe3+ | R | R | R | - | - | R | G | H | R | RK |
| Co2+ | M | R | R | R | H | R | H | H | R | H |
| Ni2+ | M | R | R | R | RK | R | H | H | R | H |
| Cu2+ | M | R | R | - | H | R | G | H | R | H |
| Zn2+ | M | R | R | R | RK | R | H | H | R | H |
| CD 2+ | R | R | R | R | RK | R | H | H | R | H |
| Hg2+ | R | R | M | NK | NK | R | H | H | R | H |
| Hg 2 2+ | R | NK | NK | NK | RK | R | H | H | M | H |
| Ag+ | R | NK | NK | NK | NK | R | H | H | M | H |
Legend:
P - the substance is highly soluble in water; M - slightly soluble; H - practically insoluble in water, but easily soluble in weak or dilute acids; RK - insoluble in water and soluble only in strong inorganic acids; NK - insoluble neither in water nor in acids; G - completely hydrolyzes upon dissolution and does not exist in contact with water. A dash means that such a substance does not exist at all.
In aqueous solutions, salts completely or partially dissociate into ions. Salts of weak acids and/or weak bases undergo hydrolysis. Aqueous salt solutions contain hydrated ions, ion pairs, and more complex chemical forms, including hydrolysis products, etc. A number of salts are also soluble in alcohols, acetone, acid amides, and other organic solvents.
From aqueous solutions, salts can crystallize in the form of crystalline hydrates, from non-aqueous solutions - in the form of crystalline solvates, for example CaBr 2 3C 2 H 5 OH.
Data on various processes occurring in water-salt systems, on the solubility of salts in their joint presence depending on temperature, pressure and concentration, on the composition of solid and liquid phases can be obtained by studying the solubility diagrams of water-salt systems.
General methods for the synthesis of salts.
1. Obtaining medium salts:
1) metal with non-metal: 2Na + Cl 2 = 2NaCl
2) metal with acid: Zn + 2HCl = ZnCl 2 + H 2
3) metal with a salt solution of a less active metal Fe + CuSO 4 = FeSO 4 + Cu
4) basic oxide with acid oxide: MgO + CO 2 = MgCO 3
5) basic oxide with acid CuO + H 2 SO 4 \u003d CuSO 4 + H 2 O
6) bases with acidic oxide Ba (OH) 2 + CO 2 = BaCO 3 + H 2 O
7) bases with acid: Ca (OH) 2 + 2HCl \u003d CaCl 2 + 2H 2 O
8) acid salts: MgCO 3 + 2HCl = MgCl 2 + H 2 O + CO 2
BaCl 2 + H 2 SO 4 \u003d BaSO 4 + 2HCl
9) a base solution with a salt solution: Ba (OH) 2 + Na 2 SO 4 \u003d 2NaOH + BaSO 4
10) solutions of two salts 3CaCl 2 + 2Na 3 PO 4 = Ca 3 (PO 4) 2 + 6NaCl
2. Obtaining acid salts:
1. Interaction of an acid with a lack of a base. KOH + H 2 SO 4 \u003d KHSO 4 + H 2 O
2. Interaction of a base with an excess of acid oxide
Ca(OH) 2 + 2CO 2 = Ca(HCO 3) 2
3. Interaction of an average salt with acid Ca 3 (PO 4) 2 + 4H 3 PO 4 \u003d 3Ca (H 2 PO 4) 2
3. Obtaining basic salts:
1. Hydrolysis of salts formed by a weak base and a strong acid
ZnCl 2 + H 2 O \u003d Cl + HCl
2. Addition (drop by drop) of small amounts of alkalis to solutions of medium metal salts AlCl 3 + 2NaOH = Cl + 2NaCl
3. Interaction of salts of weak acids with medium salts
2MgCl 2 + 2Na 2 CO 3 + H 2 O \u003d 2 CO 3 + CO 2 + 4NaCl
4. Obtaining complex salts:
1. Reactions of salts with ligands: AgCl + 2NH 3 = Cl
FeCl 3 + 6KCN] = K 3 + 3KCl
5. Getting double salts:
1. Joint crystallization of two salts:
Cr 2 (SO 4) 3 + K 2 SO 4 + 24H 2 O \u003d 2 + NaCl
4. Redox reactions due to the properties of the cation or anion. 2KMnO 4 + 16HCl = 2MnCl 2 + 2KCl + 5Cl 2 + 8H 2 O
2. Chemical properties of acid salts:
Thermal decomposition to medium salt
Ca (HCO 3) 2 \u003d CaCO 3 + CO 2 + H 2 O
Interaction with alkali. Obtaining medium salt.
Ba(HCO 3) 2 + Ba(OH) 2 = 2BaCO 3 + 2H 2 O
3. Chemical properties of basic salts:
Thermal decomposition. 2 CO 3 \u003d 2CuO + CO 2 + H 2 O
Interaction with acid: formation of an average salt.
Sn(OH)Cl + HCl = SnCl 2 + H 2 O
4. Chemical properties of complex salts:
1. Destruction of complexes due to the formation of poorly soluble compounds:
2Cl + K 2 S \u003d CuS + 2KCl + 4NH 3
2. Exchange of ligands between the outer and inner spheres.
K 2 + 6H 2 O \u003d Cl 2 + 2KCl
5. Chemical properties of double salts:
Interaction with alkali solutions: KCr(SO 4) 2 + 3KOH = Cr(OH) 3 + 2K 2 SO 4
2. Recovery: KCr (SO 4) 2 + 2H ° (Zn, diluted H 2 SO 4) \u003d 2CrSO 4 + H 2 SO 4 + K 2 SO 4
The raw materials for the industrial production of a number of chloride salts, sulfates, carbonates, Na, K, Ca, Mg borates are sea and ocean water, natural brines formed during its evaporation, and solid deposits of salts. For a group of minerals that form sedimentary salt deposits (sulfates and chlorides of Na, K and Mg), the code name “natural salts” is used. The largest deposits of potassium salts are located in Russia (Solikamsk), Canada and Germany, powerful deposits of phosphate ores - in North Africa, Russia and Kazakhstan, NaNO3 - in Chile.
Salts are used in food, chemical, metallurgical, glass, leather, textile industries, agriculture, medicine, etc.
The main types of salts
1. Borates(oxoborates), salts of boric acids: metaboric HBO 2, orthoboric H 3 BO 3 and polyboric acids not isolated in the free state. According to the number of boron atoms in the molecule, they are divided into mono-, di, tetra-, hexaborates, etc. Borates are also called according to the acids that form them and according to the number of moles of B 2 O 3 per 1 mole of the basic oxide. So various metaborates can be called monoborates if they contain an anion B (OH) 4 or a chain anion (BO 2) n n-diborates - if they contain a double chain anion (B 2 O 3 (OH) 2) n 2n-triborates - if they contain ring anion (B 3 O 6) 3-.
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