Salts and their types. Names and formulas of salts

Salts are the product of replacing hydrogen atoms in an acid with a metal. Soluble salts in soda dissociate into a metal cation and an acid residue anion. Salts are divided into:

· Average

· Basic

· Complex

· Double

· Mixed

Medium salts. These are products of complete replacement of hydrogen atoms in an acid with metal atoms, or with a group of atoms (NH 4 +): MgSO 4, Na 2 SO 4, NH 4 Cl, Al 2 (SO 4) 3.

The names of medium salts come from the names of metals and acids: CuSO 4 - copper sulfate, Na 3 PO 4 - sodium phosphate, NaNO 2 - sodium nitrite, NaClO - sodium hypochlorite, NaClO 2 - sodium chlorite, NaClO 3 - sodium chlorate, NaClO 4 - sodium perchlorate, CuI - copper(I) iodide, CaF 2 - calcium fluoride. You also need to remember a few trivial names: NaCl - table salt, KNO3 - potassium nitrate, K2CO3 - potash, Na2CO3 - soda ash, Na2CO3∙10H2O - crystalline soda, CuSO4 - copper sulfate, Na 2 B 4 O 7 . 10H 2 O - borax, Na 2 SO 4 . 10H 2 O-Glauber's salt. Double salts. This salt , containing two types of cations (hydrogen atoms polybasic acids are replaced by two different cations): MgNH 4 PO 4, KAl (SO 4) 2, NaKSO 4 .Double salts as individual compounds exist only in crystalline form. When dissolved in water they are completelydissociate into metal ions and acidic residues (if the salts are soluble), for example:

NaKSO 4 ↔ Na + + K + + SO 4 2-

It is noteworthy that the dissociation of double salts in aqueous solutions occurs in 1 step. To name salts of this type, you need to know the names of the anion and two cations: MgNH4PO4 - magnesium ammonium phosphate.

Complex salts.These are particles (neutral molecules orions ), which are formed as a result of joining to a given ion (or atom ), called complexing agent, neutral molecules or other ions called ligands. Complex salts are divided into:

1) Cationic complexes

Cl 2 - tetraammine zinc(II) dichloride
Cl2- di hexaammine cobalt(II) chloride

2) Anion complexes

K 2 - potassium tetrafluoroberyllate(II)
Li-lithium tetrahydridealuminate(III)
K 3 -potassium hexacyanoferrate(III)

The theory of the structure of complex compounds was developed by the Swiss chemist A. Werner.

Acid salts– products of incomplete replacement of hydrogen atoms in polybasic acids with metal cations.

For example: NaHCO 3

Chemical properties:
React with metals located in the voltage series to the left of hydrogen.
2KHSO 4 +Mg→H 2 +Mg(SO) 4 +K 2 (SO) 4

Note that for such reactions it is dangerous to take alkali metals, because they will first react with water with a large release of energy, and an explosion will occur, since all reactions occur in solutions.

2NaHCO 3 +Fe→H 2 +Na 2 CO 3 +Fe 2 (CO 3) 3 ↓

Acid salts react with alkali solutions and form medium salt(s) and water:

NaHCO 3 +NaOH→Na 2 CO 3 +H 2 O

2KHSO 4 +2NaOH→2H 2 O+K 2 SO 4 +Na 2 SO 4

Acid salts react with solutions of medium salts if gas is released, a precipitate forms, or water is released:

2KHSO 4 +MgCO 3 →MgSO 4 +K 2 SO 4 +CO 2 +H 2 O

2KHSO 4 +BaCl 2 →BaSO 4 ↓+K 2 SO 4 +2HCl

Acid salts react with acids if the acid product of the reaction is weaker or more volatile than the one added.

NaHCO 3 +HCl→NaCl+CO 2 +H 2 O

Acid salts react with basic oxides to release water and medium salts:

2NaHCO 3 +MgO→MgCO 3 ↓+Na 2 CO 3 +H 2 O

2KHSO 4 +BeO→BeSO 4 +K 2 SO 4 +H 2 O

Acid salts (in particular bicarbonates) decompose under the influence of temperature:
2NaHCO 3 → Na 2 CO 3 +CO 2 +H 2 O

Receipt:

Acid salts are formed when an alkali is exposed to an excess solution of a polybasic acid (neutralization reaction):

NaOH+H 2 SO 4 →NaHSO 4 +H 2 O

Mg(OH) 2 +2H 2 SO 4 →Mg(HSO 4) 2 +2H 2 O

Acid salts are formed by dissolving basic oxides in polybasic acids:
MgO+2H 2 SO 4 →Mg(HSO 4) 2 +H 2 O

Acid salts are formed when metals are dissolved in an excess solution of a polybasic acid:
Mg+2H 2 SO 4 →Mg(HSO 4) 2 +H 2

Acidic salts are formed as a result of the interaction of an average salt and an acid, which forms the anion of the average salt:
Ca 3 (PO 4) 2 +H 3 PO 4 →3CaHPO 4

Basic salts:

Basic salts are a product of incomplete replacement of the hydroxo group in the molecules of polyacid bases with acidic residues.

Example: MgOHNO 3,FeOHCl.

Chemical properties:
Basic salts react with excess acid to form a medium salt and water.

MgOHNO 3 +HNO 3 →Mg(NO 3) 2 +H 2 O

Basic salts are decomposed by temperature:

2 CO 3 →2CuO+CO 2 +H 2 O

Preparation of basic salts:
Interaction of salts of weak acids with medium salts:
2MgCl 2 +2Na 2 CO 3 +H 2 O→ 2 CO 3 +CO 2 +4NaCl
Hydrolysis of salts formed by a weak base and a strong acid:

ZnCl 2 +H 2 O→Cl+HCl

Most basic salts are slightly soluble. Many of them are minerals, e.g. malachite Cu 2 CO 3 (OH) 2 and hydroxyapatite Ca 5 (PO 4) 3 OH.

The properties of mixed salts are not discussed in school course chemistry, but the definition is important to know.
Mixed salts are salts in which the acid residues of two different acids are attached to one metal cation.

A good example is Ca(OCl)Cl bleaching lime (bleach).

Nomenclature:

1. Salt contains a complex cation

First, the cation is named, then the ligands included in the inner sphere are the anions, ending in “o” ( Cl - - chloro, OH - -hydroxy), then ligands, which are neutral molecules ( NH 3 -amine, H 2 O -aquo).If there are more than 1 identical ligands, their number is denoted by Greek numerals: 1 - mono, 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa, 9 - nona, 10 - deca. The latter is called the complexing ion, indicating its valence in parentheses if it is variable.

[Ag (NH 3 ) 2 ](OH )-silver diamine hydroxide ( I)

[Co (NH 3 ) 4 Cl 2 ] Cl 2 -chloride dichloro o cobalt tetraamine ( III)

2. The salt contains a complex anion.

First, the ligands - anions - are named, then the neutral molecules entering the inner sphere ending in “o” are named, indicating their number with Greek numerals. The latter is called a complexing ion in Latin, with the suffix “at”, indicating the valency in brackets. Next, the name of the cation located in the outer sphere is written; the number of cations is not indicated.

Potassium K 4 -hexacyanoferrate (II) (reagent for Fe 3+ ions)

K 3 - potassium hexacyanoferrate (III) (reagent for Fe 2+ ions)

Na 2 -sodium tetrahydroxozincate

Most complexing ions are metals. The d elements exhibit the greatest tendency to complex formation. Around the central complexing ion are oppositely charged ions or neutral molecules - ligands or addends.

The complexing ion and ligands make up the inner sphere of the complex (in square brackets); the number of ligands coordinated around the central ion is called the coordination number.

The ions that do not enter the inner sphere form the outer sphere. If the complex ion is a cation, then there are anions in the outer sphere and vice versa, if the complex ion is an anion, then there are cations in the outer sphere. The cations are usually ions of alkali and alkaline earth metals, ammonium cation. When dissociated, complex compounds give complex complex ions that are quite stable in solutions:

K 3 ↔3K + + 3-

If we are talking about acidic salts, then when reading the formula the prefix hydro- is pronounced, for example:
Sodium hydrosulfide NaHS

Sodium bicarbonate NaHCO 3

With basic salts the prefix is used hydroxo- or dihydroxo-

(depends on the oxidation state of the metal in the salt), for example:
magnesium hydroxychlorideMg(OH)Cl, aluminum dihydroxychloride Al(OH) 2 Cl

Methods for obtaining salts:

1. Direct interaction metal with non-metal . This method can be used to obtain salts of oxygen-free acids.

Zn+Cl 2 →ZnCl 2

2. Reaction between acid and base (neutralization reaction). Reactions of this type have a large practical significance(qualitative reactions to most cations), they are always accompanied by the release of water:

NaOH+HCl→NaCl+H 2 O

Ba(OH) 2 +H 2 SO 4 →BaSO 4 ↓+2H 2 O

3. Interaction of a basic oxide with an acidic one :

SO 3 +BaO→BaSO 4 ↓

4. Reaction between acid oxide and base :

2NaOH+2NO 2 →NaNO 3 +NaNO 2 +H 2 O

NaOH+CO 2 →Na 2 CO 3 +H 2 O

5. Reaction between basic oxide and acid :

Na 2 O+2HCl→2NaCl+H 2 O

CuO+2HNO 3 =Cu(NO 3) 2 +H 2 O

6. Direct interaction of metal with acid. This reaction may be accompanied by the evolution of hydrogen. Whether hydrogen will be released or not depends on the activity of the metal, the chemical properties of the acid and its concentration (see Properties of concentrated sulfuric and nitric acids).

Zn+2HCl=ZnCl 2 +H 2

H 2 SO 4 +Zn=ZnSO 4 +H 2

7. Interaction of salt with acid . This reaction will occur provided that the acid forming the salt is weaker or more volatile than the acid that reacted:

Na 2 CO 3 +2HNO 3 =2NaNO 3 +CO 2 +H 2 O

8. Interaction of salt with acid oxide. Reactions occur only when heated, therefore, the oxide that enters the reaction must be less volatile than the one formed after the reaction:

CaCO 3 +SiO 2 =CaSiO 3 +CO 2

9. Interaction of non-metal with alkali . Halogens, sulfur and some other elements, interacting with alkalis, give oxygen-free and oxygen-containing salts:

Cl 2 +2KOH=KCl+KClO+H 2 O (reaction occurs without heating)

Cl 2 +6KOH=5KCl+KClO 3 +3H 2 O (the reaction occurs with heating)

3S+6NaOH=2Na 2 S+Na 2 SO 3 +3H 2 O

10. Interaction between two salts. This is the most common method of obtaining salts. To do this, both salts that entered into the reaction must be highly soluble, and since this is an ion exchange reaction, in order for it to proceed to completion, one of the reaction products must be insoluble:

Na 2 CO 3 +CaCl 2 =2NaCl+CaCO 3 ↓

Na 2 SO 4 + BaCl 2 = 2NaCl + BaSO 4 ↓

11. Interaction between salt and metal . The reaction occurs if the metal is in the metal voltage series to the left of the one contained in the salt:

Zn+CuSO 4 =ZnSO 4 +Cu↓

12. Thermal decomposition of salts . When some oxygen-containing salts are heated, new ones are formed, with less oxygen content, or containing no oxygen at all:

2KNO 3 → 2KNO 2 +O 2

4KClO 3 → 3KClO 4 +KCl

2KClO 3 → 3O 2 +2KCl

13. Interaction of a nonmetal with salt. Some non-metals are capable of combining with salts to form new salts:

Cl 2 +2KI=2KCl+I 2 ↓

14. Reaction of base with salt . Since this is an ion exchange reaction, in order for it to proceed to completion, it is necessary that 1 of the reaction products be insoluble (this reaction is also used to convert acidic salts to intermediate ones):

FeCl 3 +3NaOH=Fe(OH) 3 ↓ +3NaCl

NaOH+ZnCl 2 = (ZnOH)Cl+NaCl

KHSO 4 +KOH=K 2 SO 4 +H 2 O

Double salts can also be obtained in this way:

NaOH+ KHSO 4 =KNaSO 4 +H 2 O

15. Interaction of metal with alkali. Metals that are amphoteric react with alkalis, forming complexes:

2Al+2NaOH+6H 2 O=2Na+3H 2

16. Interaction salts (oxides, hydroxides, metals) with ligands:

2Al+2NaOH+6H 2 O=2Na+3H 2

AgCl+3NH 4 OH=OH+NH 4 Cl+2H 2 O

3K 4 +4FeCl 3 =Fe 3 3 +12KCl

AgCl+2NH 4 OH=Cl+2H 2 O

Editor: Galina Nikolaevna Kharlamova

Salts are electrolytes that dissociate in aqueous solutions to form a metal cation and an acid residue anion.
The classification of salts is given in table. 9.

When writing formulas for any salts, you must be guided by one rule: the total charges of cations and anions must be equal in absolute value. Based on this, indexes should be placed. For example, when writing the formula for aluminum nitrate, we take into account that the charge of the aluminum cation is +3, and the pitrate ion is 1: AlNO 3 (+3), and using indices we equalize the charges (the least common multiple for 3 and 1 is 3. Divide 3 on absolute value charge of the aluminum cation - the index is obtained. We divide 3 by the absolute value of the charge of the NO 3 anion - we get index 3). Formula: Al(NO 3) 3

Medium, or normal, salts contain only metal cations and anions of the acid residue. Their names are derived from the Latin name of the element forming the acidic residue by adding the appropriate ending depending on the oxidation state of that atom. For example, the sulfuric acid salt Na 2 SO 4 is called (oxidation state of sulfur +6), salt Na 2 S - (oxidation state of sulfur -2), etc. In the table. Table 10 shows the names of salts formed by the most widely used acids.

The names of the middle salts underlie all other groups of salts.

■ 106 Write the formulas of the following average salts: a) calcium sulfate; b) magnesium nitrate; c) aluminum chloride; d) zinc sulfide; d) ; f) potassium carbonate; g) calcium silicate; h) iron (III) phosphate.

Acid salts differ from average salts in that their composition, in addition to the metal cation, includes a hydrogen cation, for example NaHCO3 or Ca(H2PO4)2. An acid salt can be thought of as the product of incomplete replacement of hydrogen atoms in an acid with a metal. Consequently, acid salts can only be formed by two or more basic acids.
The acid salt molecule usually contains an “acidic” ion, the charge of which depends on the stage of dissociation of the acid. For example, the dissociation of phosphoric acid occurs in three steps:

At the first stage of dissociation, a singly charged anion H 2 PO 4 is formed. Consequently, depending on the charge of the metal cation, the formulas of the salts will look like NaH 2 PO 4, Ca(H 2 PO 4) 2, Ba(H 2 PO 4) 2, etc. At the second stage of dissociation, a doubly charged HPO anion is formed 2 4 — . The formulas of the salts will look like this: Na 2 HPO 4, CaHPO 4, etc. The third stage of dissociation does not produce acidic salts.
The names of acid salts are derived from the names of average salts with the addition of the prefix hydro- (from the word “hydrogenium” -):
NaHCO 3 - sodium bicarbonate KHCO 4 - potassium hydrogen sulfate CaHPO 4 - calcium hydrogen phosphate
If the acidic ion contains two hydrogen atoms, for example H 2 PO 4 -, the prefix di- (two) is added to the name of the salt: NaH 2 PO 4 - sodium dihydrogen phosphate, Ca(H 2 PO 4) 2 - calcium dihydrogen phosphate, etc. .d.

■ 107. Write the formulas of the following acid salts: a) calcium hydrogen sulfate; b) magnesium dihydrogen phosphate; c) aluminum hydrogen phosphate; d) barium bicarbonate; e) sodium hydrosulfite; f) magnesium hydrosulfite.
108. Is it possible to obtain acidic salts of hydrochloric and nitric acid. Justify your answer.

Basic salts differ from others in that, in addition to the metal cation and the anion of the acid residue, they contain hydroxyl anions, for example Al(OH)(NO3) 2. Here the charge of the aluminum cation is +3, and the charges of the hydroxyl ion-1 and two nitrate ions are 2, for a total of 3.
The names of the main salts are derived from the names of the middle salts with the addition of the word basic, for example: Cu 2 (OH) 2 CO 3 - basic copper carbonate, Al (OH) 2 NO 3 - basic aluminum nitrate.

■ 109. Write the formulas of the following basic salts: a) basic iron (II) chloride; b) basic iron (III) sulfate; c) basic copper (II) nitrate; d) basic calcium chloride; e) basic magnesium chloride; f) basic iron (III) sulfate g) basic aluminum chloride.

Formulas of double salts, for example KAl(SO4)3, are built based on the total charges of both metal cations and the total charge of the anion

The total charge of cations is + 4, the total charge of anions is -4.
The names of double salts are formed in the same way as the middle ones, only the names of both metals are indicated: KAl(SO4)2 - potassium-aluminum sulfate.

■ 110. Write the formulas of the following salts:
a) magnesium phosphate; b) magnesium hydrogen phosphate; c) lead sulfate; d) barium hydrogen sulfate; e) barium hydrosulfite; f) potassium silicate; g) aluminum nitrate; h) copper (II) chloride; i) iron (III) carbonate; j) calcium nitrate; l) potassium carbonate.

Chemical properties of salts

1. All medium salts are strong electrolytes and easily dissociate:
Na 2 SO 4 ⇄ 2Na + + SO 2 4 —
Medium salts can interact with metals that are a number of voltages to the left of the metal that is part of the salt:
Fe + CuSO 4 = Cu + FeSO 4
Fe + Сu 2+ + SO 2 4 — = Сu + Fe 2+ + SO 2 4 —
Fe + Cu 2+ = Cu + Fe 2+
2. Salts react with alkalis and acids according to the rules described in the sections “Bases” and “Acids”:
FeCl 3 + 3NaOH = Fe(OH) 3 ↓ + 3NaCl
Fe 3+ + 3Cl - + 3Na + + 3OH - = Fe(OH) 3 + 3Na + + 3Cl -
Fe 3+ + 3OH - =Fe(OH) 3
Na 2 SO 3 + 2HCl = 2NaCl + H 2 SO 3
2Na + + SO 2 3 - + 2H + + 2Cl - = 2Na + + 2Cl - + SO 2 + H 2 O
2H + + SO 2 3 - = SO 2 + H 2 O
3. Salts can interact with each other, resulting in the formation of new salts:
AgNO 3 + NaCl = NaNO 3 + AgCl
Ag + + NO 3 - + Na + + Cl - = Na + + NO 3 - + AgCl
Ag + + Cl - = AgCl
Since these exchange reactions are carried out mainly in aqueous solutions, they occur only when one of the resulting salts precipitates.
All exchange reactions proceed in accordance with the conditions for the reactions to proceed to completion, listed in § 23, p. 89.

■ 111. Write equations following reactions and, using the solubility table, determine whether they will pass to the end:
a) barium chloride + ;
b) aluminum chloride + ;
c) sodium phosphate + calcium nitrate;
d) magnesium chloride + potassium sulfate;
e) + lead nitrate;
f) potassium carbonate + manganese sulfate;
g) + potassium sulfate.
Write the equations in molecular and ionic forms.

■ 112. Which of the following substances will iron (II) chloride react with: a) ; b) calcium carbonate; c) sodium hydroxide; d) silicon anhydride; d) ; f) copper (II) hydroxide; and) ?

113. Describe the properties of calcium carbonate as an average salt. Write all equations in molecular and ionic forms.
114. How to carry out a series of transformations:

Write all equations in molecular and ionic forms.
115. What amount of salt will be obtained from the reaction of 8 g of sulfur and 18 g of zinc?
116. What volume of hydrogen will be released when 7 g of iron reacts with 20 g of sulfuric acid?
117. How many moles of table salt will be obtained from the reaction of 120 g of sodium hydroxide and 120 g of hydrochloric acid?
118. How much potassium nitrate will be obtained from the reaction of 2 moles of potassium hydroxide and 130 g of nitric acid?

Hydrolysis of salts

A specific property of salts is their ability to hydrolyze - to undergo hydrolysis (from the Greek “hydro” - water, “lysis” - decomposition), i.e. decomposition under the influence of water. It is impossible to consider hydrolysis as decomposition in the sense in which we usually understand it, but one thing is certain - it always participates in the hydrolysis reaction.
- very weak electrolyte, dissociates poorly
H 2 O ⇄ H + + OH -
and does not change the color of the indicator. Alkalis and acids change the color of the indicators, since when they dissociate in solution, an excess of OH - ions (in the case of alkalis) and H + ions in the case of acids is formed. In salts such as NaCl, K 2 SO 4, which are formed by a strong acid (HCl, H 2 SO 4) and a strong base (NaOH, KOH), indicators do not change color, since in a solution of these
There is practically no hydrolysis of salts.
During the hydrolysis of salts, four cases are possible, depending on whether the salt was formed with a strong or weak acid and base.
1. If we take a salt of a strong base and a weak acid, for example K 2 S, the following will happen. Potassium sulfide dissociates into ions as a strong electrolyte:
K 2 S ⇄ 2K + + S 2-
Along with this, it weakly dissociates:
H 2 O ⇄ H + + OH —
The sulfur anion S2- is an anion of weak hydrosulfide acid, which dissociates poorly. This leads to the fact that the S 2- anion begins to attach hydrogen cations from water, gradually forming low-dissociating groups:
S 2- + H + + OH — = HS — + OH —
HS - + H + + OH - = H 2 S + OH -
Since the H + cations from the water are bound, and the OH - anions remain, the reaction of the medium becomes alkaline. Thus, during the hydrolysis of salts formed by a strong base and a weak acid, the reaction of the medium is always alkaline.

■ 119.Using ionic equations, explain the process of hydrolysis of sodium carbonate.

2. If you take a salt formed by a weak base and a strong acid, for example Fe(NO 3) 3, then when it dissociates, ions are formed:
Fe(NO 3) 3 ⇄ Fe 3+ + 3NO 3 -
The Fe3+ cation is a cation of a weak base - iron, which dissociates very poorly. This leads to the fact that the Fe 3+ cation begins to attach OH - anions from water, forming slightly dissociating groups:
Fe 3+ + H + + OH - = Fe(OH) 2+ + + H +
and onwards
Fe(OH) 2+ + H + + OH - = Fe(OH) 2 + + H +
Finally, the process can reach its last stage:
Fe(OH) 2 + + H + + OH - = Fe(OH) 3 + H +
Consequently, there will be an excess of hydrogen cations in the solution.
Thus, during the hydrolysis of a salt formed by a weak base and a strong acid, the reaction of the medium is always acidic.

■ 120. Using ionic equations, explain the course of hydrolysis of aluminum chloride.

3. If a salt is formed by a strong base and a strong acid, then neither the cation nor the anion binds water ions and the reaction remains neutral. Hydrolysis practically does not occur.
4. If a salt is formed by a weak base and a weak acid, then the reaction of the medium depends on their degree of dissociation. If the base and acid have almost the same value, then the reaction of the medium will be neutral.

■ 121. It is often seen how during an exchange reaction, instead of the expected salt precipitate, a metal precipitate precipitates, for example, in the reaction between iron (III) chloride FeCl 3 and sodium carbonate Na 2 CO 3, not Fe 2 (CO 3) 3 is formed, but Fe( OH) 3 . Explain this phenomenon.
122. Among the salts listed below, indicate those that undergo hydrolysis in solution: KNO 3, Cr 2 (SO 4) 3, Al 2 (CO 3) 3, CaCl 2, K 2 SiO 3, Al 2 (SO 3) 3.

Features of the properties of acid salts

Acidic salts have slightly different properties. They can enter into reactions with the preservation and destruction of the acidic ion. For example, the reaction of an acid salt with an alkali results in the neutralization of the acid salt and the destruction of the acid ion, for example:
NaHSO4 + KOH = KNaSO4 + H2O
double salt
Na + + HSO 4 - + K + + OH - = K + + Na + + SO 2 4 - + H2O
HSO 4 - + OH - = SO 2 4 - + H2O
The destruction of an acidic ion can be represented as follows:
HSO 4 — ⇄ H + + SO 4 2-
H + + SO 2 4 - + OH - = SO 2 4 - + H2O
The acidic ion is also destroyed when reacting with acids:
Mg(HCO3)2 + 2HCl = MgCl2 + 2H2Co3
Mg 2+ + 2НСО 3 — + 2Н + + 2Сl — = Mg 2+ + 2Сl — + 2Н2O + 2СO2
2HCO 3 - + 2H + = 2H2O + 2CO2
HCO 3 - + H + = H2O + CO2
Neutralization can be carried out with the same alkali that formed the salt:
NaHSO4 + NaOH = Na2SO4 + H2O
Na + + HSO 4 - + Na + + OH - = 2Na + + SO 4 2- + H2O
HSO 4 - + OH - = SO 4 2- + H2O
Reactions with salts occur without destruction of the acidic ion:
Ca(HCO3)2 + Na2CO3 = CaCO3 + 2NaHCO3
Ca 2+ + 2НСО 3 — + 2Na + + СО 2 3 — = CaCO3↓+ 2Na + + 2НСО 3 —
Ca 2+ + CO 2 3 - = CaCO3
■ 123. Write the equations for the following reactions in molecular and ionic forms:
a) potassium hydrosulfide +;
b) sodium hydrogen phosphate + potassium hydroxide;
c) calcium dihydrogen phosphate + sodium carbonate;
d) barium bicarbonate + potassium sulfate;
e) calcium hydrosulfite +.

Obtaining salts

Based on the studied properties of the main classes inorganic substances You can deduce 10 ways to obtain salts.
1. Interaction of metal with non-metal:
2Na + Cl2 = 2NaCl
Only salts of oxygen-free acids can be obtained in this way. This is not an ionic reaction.
2. Interaction of metal with acid:
Fe + H2SO4 = FeSO4 + H2
Fe + 2H + + SO 2 4 - =Fe 2+ + SO 2 4 - + H2
Fe + 2H + = Fe 2+ + H2
3. Interaction of metal with salt:
Сu + 2AgNO3 = Cu(NO3)2 + 2Ag↓
Сu + 2Ag + + 2NO 3 - = Cu 2+ 2NO 3 - + 2Ag↓
Сu + 2Ag + = Cu 2+ + 2Ag
4. Interaction of a basic oxide with an acid:
СuО + H2SO4 = CuSO4 + H2O
CuO + 2H + + SO 2 4 - = Cu 2+ + SO 2 4 - + H2O
СuО + 2Н + = Cu 2+ + H2O
5. The interaction of a basic oxide with an acid anhydride:
3CaO + P2O5 = Ca3(PO4)2
The reaction is not ionic in nature.
6. Interaction of an acidic oxide with a base:
CO2 + Ca(OH)2 = CaCO3 + H2O
CO2 + Ca 2+ + 2OH - = CaCO3 + H2O
7, Interaction of acids with bases (neutralization):
HNO3 + KOH = KNO3 + H2O
H + + NO 3 — + K + + OH — = K + + NO 3 — + H2O
H + + OH - = H2O

Salts – complex substances, which are the product of complete or incomplete replacement of hydrogen atoms of an acid with metal atoms, or replacement of hydroxyl groups of a base with an acidic residue.

Depending on the composition, salts are divided into medium (Na2SO4, K3PO4), acidic (NaHCO3, MgHPO4), basic (FeOHCl2, Al(OH)2Cl, (CaOH)2CO3, double (KAl(SO4)2), complex (Ag[( NH3)2]Cl, K4).

Medium salts

Medium salts are salts that are the product of complete replacement of the hydrogen atoms of the corresponding acid with metal atoms or the NH4+ ion. For example:

H2CO3 ® (NH4)2CO3; H3PO4 ® Na3PO4

The name of the average salt is formed from the name of the anion followed by the name of the cation. For salts of oxygen-free acids, the name of the salt is made up of the Latin name of the non-metal with the addition of the suffix –id, for example, NaCl - sodium chloride. If a non-metal exhibits a variable degree of oxidation, then after its name the oxidation state of the metal is indicated in parentheses in Roman numerals: FeS - iron (II) sulfide, Fe2S3 - iron (III) sulfide.

For salts of oxygen-containing acids, the ending is added to the Latin root of the element name –at for higher oxidation states, -it for lower ones. For example,

K2SiO3 – potassium silicate, KNO2 – potassium nitrite,

KNO3 – potassium nitrate, K3PO4 – potassium phosphate,

Fe2(SO4)3 – iron (III) sulfate, Na2SO3 – sodium sulfite.

For salts of some acids the prefix is used –hypo for lower oxidation states and –trans for high oxidation states. For example,

KClO – potassium hypochlorite, KClO2 – potassium chlorite,

KClO3 – potassium chlorate, KClO4 – potassium perchlorate.

Methods for obtaining medium salts:

Interaction of metals with non-metals, acids and salts:

2Na + Cl2 = 2NaCl

Zn + 2HCl = ZnCl2 + H2

Fe + CuSO4 = FeSO4 + Cu

Interaction of oxides:

basic with acids BaO + 2HNO3 = Ba(NO3)2 + H2O

acidic with alkali 2NaOH + SiO2 = Na2SiO3 + H2O

basic oxides with acidic Na2O + CO2 = Na2CO3

The interaction of acids with bases and with amphoteric hydroxides:

KOH + HCl = KCl + H2O

Cr(OH)3 + 3HNO3 = Cr(NO3)3 + 3H2O

The interaction of salts with acids, with alkalis and salts:

Na2CO3 + 2HCl = 2NaCl + CO2 + H2O

FeCl3 + 3KOH = 3KCl + Fe(OH)3¯

Na2SO4 + BaCl2 = BaSO4¯ + 2NaCl

Chemical properties of medium salts:

Interaction with metals

Zn + Hg(NO3)2 = Zn(NO3)2 + Hg

Interaction with acids

AgNO3 + HCl = AgCl¯ + HNO3

Interaction with alkalis

CuSO4 + 2NaOH = Cu(OH)2¯ + Na2SO4

Interaction with salts

CaCl2 + Na2CO3 = CaCO3¯ + 2NaCl

Decomposition of salts

NH4Cl = NH3 + HCl

CaCO3 = CaO + CO2

(NH4)2Cr2O7 = N2 + Cr2O3 + 4H2O

Acid salts

Acid salts are products of incomplete replacement of hydrogen atoms in molecules of polybasic acids with metal atoms.

For example: H2CO3 ® NaHCO3

H3PO4 ® NaH2PO4 ® Na2HPO4

When naming an acidic salt, the prefix is added to the name of the corresponding average salt hydro-, which indicates the presence of hydrogen atoms in the acid residue.

For example, NaHS is sodium hydrogen sulfide, Na2HPO4 is sodium hydrogen phosphate, NaH2PO4 is sodium dihydrogen phosphate.

Acid salts can be obtained:

The action of excess polybasic acids on basic oxides, alkalis and medium salts:

K2O + 2H2S = 2KHS + H2O

NaOH + H2SO4 = NaHSO4 + H2O

K2SO4 + H2SO4 = 2KHSO4

The action of excess acid oxides on alkalis

NaOH + CO2 = NaHCO3

Chemical properties of acid salts:

Interaction with excess alkali

Ca(HCO3)2 + Ca(OH)2 = 2CaCO3 + 2H2O

Interaction with acids

Ca(HCO3)2 + 2HCl = CaCl2 + 2H2O + 2CO2

Decomposition

Ca(HCO3)2 = CaCO3 + CO2 + H2O

Basic salts

Basic salts are products of incomplete replacement of the hydroxo group in the molecules of polyacid bases with acidic residues.

Mg(OH)2 ® MgOHNO3

Fe(OH)3 ®Fe(OH)2Cl ® FeOHCl2

When naming the main salt, the prefix is added to the name of the corresponding middle salt hydroxo-, which indicates the presence of a hydroxo group. For example, CrOHCl2 is chromium (III) hydroxychloride, Cr(OH)2Cl is chromium (III) dihydroxychloride.

Basic salts can be obtained:

Incomplete neutralization of bases by acids

>> Chemistry: Salts, their classification and properties

Of all chemical compounds salts are the most numerous class of substances. These are solid substances, they differ from each other in color and solubility in water.

Salts is a class of chemical compounds consisting of metal ions and acidic ions.

IN early XIX V. Swedish chemist I. Verzelius formulated the definition of salts as products of reactions of acids with bases, or compounds obtained by replacing hydrogen atoms in an acid with a metal. On this basis, salts are distinguished between medium, acidic and basic.

Average or normal- these are the products of complete replacement of hydrogen atoms in an acid with a metal.

It is these salts that you are already familiar with and know their nomenclature. For example:

Na2С03 - sodium carbonate, CuSO4 - copper (II) sulfate, etc.

Such salts dissociate into metal cations and anions of the acid residue:

Acid salts - these are products of incomplete replacement of hydrogen atoms in an acid with a metal.

Acid salts include, for example, baking soda, which consists of a metal cation and an acidic singly charged residue HCO3. For an acidic calcium salt, the formula is written as follows: Ca(HCO3)2.

The names of these salts are composed of the names of the salts with the addition of the word hydro, for example:

Basic salts- these are products of incomplete substitution of hydroxo groups in the base with an acid residue.

For example, such salts include the famous malachite (SiOH)2 CO3, which you read about in the tales of I. Bazhov. It consists of two main cations CuOH and a doubly charged anion of the acidic residue CO 2-3.

The CuOH+ cation has a charge of +1, so in the molecule two such cations and one doubly charged CO anion are combined into an electrically neutral salt.

The names of such salts will be the same as those of normal salts, but with the addition of the word hydroxo-, for example (CuOH)2 CO3 - copper (II) hydroxycarbonate or AlONCl2 - aluminum hydroxychloride. The vast majority of basic salts are insoluble or slightly soluble. The latter dissociate like this:

Typical salt reactions

4. Salt + metal -> another salt + another metal.

The first two exchange reactions have already been discussed in detail earlier.

The third reaction is also an exchange reaction. It flows between salt solutions and is accompanied by the formation of sediment, for example:

The fourth reaction of salts is associated with the name of the greatest Russian chemist N.N. Beketov, who in 1865 studied the ability of metals to displace other metals from salt solutions. For example, copper tu solutions of its salts can be replaced by metals such as magnesium, aluminum, Al, zinc and other metals. But copper is not replaced by mercury, silver Аg, gold Аu, since atm metals in the voltage series are located to the right than copper. But copper displaces them from salt solutions:

N. Beketov, acting with hydrogen gas under pressure on solutions of mercury and silver salts, found that the hydrogen atom, like some other metals, displaces mercury and silver from their salts.

Arranging metals, I also hydrogen according to their ability to displace each other and salt solutions. Beketov made up the series. which he called the vegetative series of metals. Later (1802 V. Nerist) it was proven that the displacement series Veketovn practically coincides with the series in which metals and hydrogen are located (to the right) in order of decreasing their reducing ability and the molar concentration of metal ions is equal to 1 mol/l. This series is called the electrochemical series of metal stresses. You have already become familiar with this series when you looked at the interaction of acids with metals and found out that metals that are located to the left of hydrogen interact with acid solutions. This is the first step in a series of voltages. It is fulfilled subject to a number of conditions that we talked about earlier.

The second rule of the stress series is as follows: each metal displaces from salt solutions all other metals located to the right of it in the stress series. This rule is also observed if the following conditions are met:

a) both salts (both the reacting one and those formed as a result of the reaction) must be soluble;
b) metals should not interact with water, therefore the metals of the main subgroups of groups I and II (for the latter, starting with Ca) do not displace other metals in salt solutions.

1. Salts are medium (normal), acidic and basic.

2. Dissociation of various salt groups.

3. Typical properties of normal salts: their interaction with acids, alkalis, other salts and metals.

4. Two rules for a series of metal stresses.

5. Conditions for reactions of salts with metals.

Complete the molecular equations of possible reactions occurring in solutions and write the corresponding ionic equations:

If the reaction cannot be carried out, explain why.

An excess of barium nitrate solution was added to 980 g of a 5% solution of weedy acid. Find the mass of the precipitate that fell.

Write down the reaction equations for all possible ways obtaining iron (II) sulfate.

Give the names of the salts.

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Salts- complex substances consisting of a metal atom or ammonium ion NH + 4 and an acid residue (sometimes containing hydrogen).

Practically all salts are ionic compounds, therefore, in salts, ions of acidic residues and metal ions are bound together

Salts are solid crystalline substances. Many substances have high temperatures melting and boiling. Based on solubility, they are divided into soluble and insoluble.

A salt is the product of partial or complete substitution of a metal for the hydrogen atoms of an acid. Hence they distinguish the following types salts:

1. Medium salts– all hydrogen atoms in the acid are replaced by a metal: Na 2 CO 3, KNO 3, etc.
2. Acid salts– not all hydrogen atoms in the acid are replaced by a metal. Of course, acid salts can only form di- or polybasic acids. Monobasic acids cannot produce acidic salts: NaHCO 3, NaH 2 PO 4, etc. d.

3. Double salts– the hydrogen atoms of a di- or polybasic acid are replaced not by one metal, but by two different ones: NaKCO 3, KAl(SO 4) 2, etc.

4. Basic salts can be considered as products of incomplete, or partial, substitution of hydroxyl groups of bases with acidic residues: Al(OH)SO 4, Zn(OH)Cl, etc.

CLASSIFICATION OF SALT

Chemical properties

1. In aqueous solutions, salts can react with alkalis.

( magnesium chloride MgCl2 reacts with sodium hydroxide, forming a new salt and a new base: )

2. Salts can react with acids. So, a solution of barium nitrate

reacts with a solution of sulfuric acid, forming a new acid and

new salt:

H. In aqueous solutions, salts can react with each other.

If you pour together aqueous solutions of calcium chloride CaCl2 and sodium carbonate Na2CO3, TO a white precipitate of water-insoluble calcium carbonate CaCO3 is formed, and sodium chloride is formed in the solution:

4. In aqueous solutions of salts, the metal included in their composition can be replaced by another metal that comes before it in the activity series.

If a pure iron wire or a piece of zinc is dipped into a solution of copper sulfate, then copper is released on their surface, and iron sulfate (if iron was omitted) or zinc sulfate (if zinc was omitted) is formed in the solution: