Chemical properties. Relation of metals to acids Acid metal salt hydrogen

I) Acid + metal = salt

1. Metals standing before H in the tension series displace H from strong acids.

Zn + 2HCl = ZnCl 2 + H 2,

2. Metals after H displace other gases.

3Cu + 8HNO 3(dil) = 3Сu (NO 3) 2 +2NO+4H 2 O

II) Acid + base(neutrolization r-I)

H 2 SO 4 + 2NaOH = Na 2 SO 4 + 2H 2 O.

III) Acid + basic oxide

H 2 SO 4 + Na 2 O = Na 2 SO 4 + 2H 2 O.

IV) Acids react with salts, if the reacting acid is stronger than the salt or if a precipitate forms.

HCI + AgNO 3 → AgCI + HNO 3

Receipt.

1. Acid oxide + water

SO 3 +H 2 O=H 2 SO 4
CO 2 +H 2 O=HCO 3

2. Anoxic acids

o Interaction simple substances

o When exposed to salt strong acids, the weaker ones stand out.

K 2 S + 2HNO 3 = 2KNO 3 + H 2 S

8.Salts, their classifications, chemical properties and preparation.

Salts – complex substances consisting of metal atoms and acidic residues.

Classification.

1.Medium salts– all hydrogen atoms in the acid are replaced by a metal.

2.Sour 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 acid salts cannot give: NaHCO 3, NaH 2 PO 4 etc. d.

3. 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.

4. 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.

Complex salts

Chemical properties.

Some salts decompose when heated

CaCO 3 = CaO + CO 2

2) Salt + acid = new salt and new acid. To carry out this reaction, it is necessary that the acid be stronger than the salt that is affected by the acid:

2NaCl + H 2 SO 4 → Na 2 SO 4 + 2HCl.

3)Salt + base = new salt and new base :

Ba(OH) 2 + MgSO 4 → BaSO 4 ↓ + Mg(OH) 2.

4)Salt + Salt = new salt

NaCl + AgNO 3 → AgCl + NaNO 3 .

Interact with metals (to the left of the metal included in the salt)

Fe + CuSO 4 → FeSO 4 + Cu↓.

Receipt.

1. Acid + base

3 . Base + acid oxide

5 . Acid+salt

7 . Salt+salt

9 . Metal+non-metal

9. Solutions. Species dispersed systems. Examples. Percentage concentration of solutions. Solve the percentage concentration problem.

Solutions is a homogeneous physicochemical system consisting of 2 or more components and products of their interaction.

An important characteristic of a solution is its composition.

Components physical state which does not change during the formation of a solution is called a solvent. If both components were in the same aggressive state before dissolution (ethanol and water), then the solvent is the one in excess

Solutions can be in different agricultural states:

1) Gas (air)

2) Liquid (Aqueous and non-aqueous: alcohol and oil)

3) Hard (metal alloys)

The solubility of a substance is called the ability of its particles to be evenly distributed between solvent particles.

The concentration of the solution is called the amount of solute contained in a specific amount of solution or solvent.

I) Mass fraction solute

II) Molar concentration of a substance (Cm) - the ratio of the amount of substance to the volume of solution

RATIO OF METALS TO ACIDS

Most often in chemical practice such strong acids as sulfuric acid are used. H 2 SO 4, hydrochloric HCl and nitrogen HNO 3 . Next, we consider the relationship of various metals to the listed acids.

Hydrochloric acid ( HCl)

Hydrochloric acid is the technical name for hydrochloric acid. It is obtained by dissolving hydrogen chloride gas in water - HCl . Due to its low solubility in water, the concentration hydrochloric acid under normal conditions does not exceed 38%. Therefore, regardless of the concentration of hydrochloric acid, the process of dissociation of its molecules in an aqueous solution proceeds actively:

HCl H + + Cl -

Hydrogen ions formed in this process H+ act as an oxidizing agent, oxidizing metals located in the activity series to the left of hydrogen . The interaction proceeds according to the following scheme:

Me + HClsalt +H 2

In this case, the salt is a metal chloride ( NiCl 2, CaCl 2, AlCl 3 ), in which the number of chloride ions corresponds to the oxidation state of the metal.

Hydrochloric acid is a weak oxidizing agent, so metals with variable valency are oxidized to lowest positive oxidation states:

Fe 0 → Fe 2+

Co 0 → Co2+

Ni 0 → Ni 2+

Cr 0 →Cr 2+

Mn 0 → Mn 2+ And etc. .

Example:

2 Al + 6 HCl → 2 AlCl 3 + 3 H 2

2│ Al 0 – 3 e- → Al 3+ - oxidation

3│2 H + + 2 e- → H 2 - recovery

Hydrochloric acid passivates lead ( Pb ). Lead passivation is caused by the formation of lead chloride, which is difficult to dissolve in water, on its surface ( II ), which protects the metal from further exposure to acid:

Pb + 2 HCl → PbCl 2 ↓ + H 2

Sulfuric acid (H 2 SO 4 )

The industry produces sulfuric acid of very high concentration (up to 98%). The difference in the oxidizing properties of a dilute solution and concentrated sulfuric acid with respect to metals should be taken into account.

Diluted sulfuric acid

In a dilute aqueous solution of sulfuric acid, most of its molecules dissociate:

H 2 SO 4 H + + HSO 4 -

HSO 4 - H + + SO 4 2-

Ions produced H+ perform a function oxidizing agent .

Like hydrochloric acid, diluted sulfuric acid solution reacts only with active metals And average activity (located in the activity series up to hydrogen).

The chemical reaction proceeds according to the following scheme:

Meh+H2SO4(razb .) → salt+H2

Example:

2 Al + 3 H 2 SO 4 (dil.) → Al 2 (SO 4) 3 + 3 H 2

1│2Al 0 – 6 e- → 2Al 3+ - oxidation

3│2 H + + 2 e- → H 2 - recovery

Metals with variable valency are oxidized with a dilute solution of sulfuric acid to lowest positive oxidation states:

Fe 0 → Fe 2+

Co 0 → Co2+

Ni 0 → Ni 2+

Cr 0 → Cr 2+

Mn 0 → Mn 2+ And etc. .

Lead ( Pb ) does not dissolve in sulfuric acid (if its concentration is below 80%) , since the resulting salt PbSO4 insoluble and creates a protective film on the metal surface.

Concentrated sulfuric acid

In a concentrated solution of sulfuric acid (above 68%), most of the molecules are in undissociated condition, therefore sulfur acts as an oxidizing agent , which is in the highest oxidation state ( S+6 ). Concentrated H2SO4 oxidizes all metals whose standard electrode potential is less than the potential of the oxidizing agent - sulfate ion SO 4 2- (0.36 V). In this regard, with concentrated react with sulfuric acid and some low-reactive metals .

The process of interaction of metals with concentrated sulfuric acid in most cases proceeds according to the following scheme:

Me + H 2 SO4 (conc.)salt + water + reduction product H 2 SO 4

Recovery products sulfuric acid can contain the following sulfur compounds:

Practice has shown that when a metal reacts with concentrated sulfuric acid, a mixture of reduction products is released, consisting of H 2 S, S and SO 2. However, one of these products is formed in predominant quantities. The nature of the main product is determined metal activity : the higher the activity, the deeper the process of sulfur reduction in sulfuric acid.

The interaction of metals of various activities with concentrated sulfuric acid can be represented by the following diagram:

Aluminum (Al ) And iron ( Fe ) do not react with cold concentrated H2SO4 , becoming covered with dense oxide films, but when heated, the reaction proceeds.

Ag , Au , Ru , Os , Rh , Ir , Pt do not react with sulfuric acid.

Concentrated sulfuric acid is strong oxidizing agent , therefore, when metals with variable valency interact with it, the latter are oxidized to higher oxidation states than in the case of a dilute acid solution:

Fe 0→ Fe3+,

Cr 0→ Cr3+,

Mn 0→Mn 4+,

Sn 0→ Sn 4+

Lead ( Pb ) oxidizes to divalent state with the formation of soluble lead hydrogen sulfatePb ( HSO 4 ) 2 .

Examples:

Active metal

8 A1 + 15 H 2 SO 4 (conc.) →4A1 2 (SO 4) 3 + 12H 2 O + 3H 2 S

4│2 Al 0 – 6 e- → 2 Al 3+ - oxidation

3│ S 6+ + 8 e → S 2- - recovery

Medium activity metal

2 Cr + 4 H 2 SO 4 (conc.) → Cr 2 (SO 4) 3 + 4 H 2 O + S

1│ 2Cr 0 – 6e →2Cr 3+ - oxidation

1│ S 6+ + 6 e → S 0 - recovery

Low-active metal

2Bi + 6H 2 SO 4 (conc.) → Bi 2 (SO 4) 3 + 6H 2 O + 3SO 2

1│ 2Bi 0 – 6e → 2Bi 3+ – oxidation

3│ S 6+ + 2 e → S 4+ - recovery

Nitric acid ( HNO 3 )

The peculiarity of nitric acid is that the nitrogen included in the composition NO 3 - has highest degree oxidation +5 and therefore has strong oxidizing properties. The maximum electrode potential for nitrate ion is 0.96 V, so nitric acid– a stronger oxidizing agent than sulfuric acid. The role of an oxidizing agent in the reactions of metals with nitric acid is played by N 5+ . Hence, hydrogen H 2 never stands out when metals interact with nitric acid ( regardless of concentration ). The process proceeds according to the following scheme:

Me + HNO 3 salt + water + reduction product HNO 3

Recovery Products HNO 3 :

Usually, when nitric acid reacts with a metal, a mixture of reduction products is formed, but as a rule, one of them is predominant. Which product will be the main one depends on the concentration of the acid and the activity of the metal.

Concentrated nitric acid

An acid solution with a density ofρ > 1.25 kg/m 3, which corresponds to
concentrations > 40%. Regardless of the activity of the metal, the interaction reaction with HNO3 (conc.) proceeds according to the following scheme:

Me + HNO 3 (conc.)→ salt + water + NO 2

Noble metals do not react with concentrated nitric acid (Au , Ru , Os , Rh , Ir , Pt ), and a number of metals (Al , Ti , Cr , Fe , Co , Ni ) at low temperature passivated with concentrated nitric acid. The reaction is possible with increasing temperature; it proceeds according to the scheme presented above.

Examples

Active metal

Al + 6 HNO 3 (conc.) → Al (NO 3 ) 3 + 3 H 2 O + 3 NO 2

1│ Al 0 – 3 e → Al 3+ - oxidation

3│ N 5+ + e → N 4+ - recovery

Medium activity metal

Fe + 6 HNO 3(conc.) → Fe(NO 3) 3 + 3H 2 O + 3NO

1│ Fe 0 – 3e → Fe 3+ - oxidation

3│ N 5+ + e → N 4+ - recovery

Low-active metal

Ag + 2HNO 3 (conc.) → AgNO 3 + H 2 O + NO 2

1│ Ag 0 – e → Ag + - oxidation

1│ N 5+ + e → N 4+ - recovery

Dilute nitric acid

Recovery product nitric acid in a dilute solution depends on metal activity involved in the reaction:

Examples:

Active metal

8 Al + 30 HNO 3(dil.) → 8Al(NO 3) 3 + 9H 2 O + 3NH 4 NO 3

8│ Al 0 – 3e → Al 3+ - oxidation

3│ N 5+ + 8 e → N 3- - recovery

The ammonia released during the reduction of nitric acid immediately reacts with excess nitric acid, forming a salt - ammonium nitrate NH4NO3:

NH 3 + HNO 3 → NH 4 NO 3.

Medium activity metal

10Cr + 36HNO 3(dil.) → 10Cr(NO 3) 3 + 18H 2 O + 3N 2

10│ Cr 0 – 3 e → Cr 3+ - oxidation

3│ 2 N 5+ + 10 e → N 2 0 - recovery

Except molecular nitrogen ( N 2 ) when metals of intermediate activity interact with dilute nitric acid, they are formed in equal quantities nitric oxide ( I) – N 2 O . In the reaction equation you need to write one of these substances .

Low-active metal

3Ag + 4HNO 3(dil.) → 3AgNO 3 + 2H 2 O + NO

3│ Ag 0 – e → Ag + - oxidation

1│ N 5+ + 3 e → N 2+ - recovery

"Aqua regia"

“Royal vodka” (previously acids were called vodkas) is a mixture of one volume of nitric acid and three to four volumes of concentrated hydrochloric acid, which has very high oxidizing activity. Such a mixture is capable of dissolving some low-active metals that do not react with nitric acid. Among them is the “king of metals” - gold. This effect of “regia vodka” is explained by the fact that nitric acid oxidizes hydrochloric acid, releasing free chlorine and forming nitrogen chloroxide ( III ), or nitrosyl chloride – NOCl:

HNO 3 + 3 HCl → Cl 2 + 2 H 2 O + NOCl

2 NOCl → 2 NO + Cl 2

Chlorine at the moment of release consists of atoms. Atomic chlorine is a strong oxidizing agent, which allows “regia vodka” to affect even the most inert “noble metals”.

The oxidation reactions of gold and platinum proceed according to the following equations:

Au + HNO 3 + 4 HCl → H + NO + 2H 2 O

3Pt + 4HNO3 + 18HCl → 3H2 + 4NO + 8H2O

For Ru, Os, Rh and Ir "Aqua regia" does not work.

E.A. Nudnova, M.V. Andryukhova

By chemical composition salts are classified into medium, sour, basic and double.

A separate type of salts are complex salts (salts with complex cations or anions). In the formulas of these salts, the complex ion is enclosed in square brackets.
Complex ions - these are complex ions consisting of ions of an element (complexing agent) and several molecules or ions (ligands) associated with it.

Examples of complex salts are given below.
a) C complex anion:

K2[PtC l] 4 - tetrachloroplatinate( II) potassium,
K2[PtCl ] 6 - hexachloroplatinate( IV) potassium,

K 3 [Fe(CN ) 6 ] - hexacyanoferrate( III) potassium.

B) C complex cation:

[Cr(NH3)6]Cl3 - hexaamminchrome chloride ( III),

[Ag(NH3)2]Cl - diamminsilver chloride ( I)
[Cu( NH3) 4 ]SO 4-tetraammine copper sulfate ( II)

Soluble salts when dissolved in water, they dissociate into metal cations and anions of acid residues.
NaCl → Na + + Cl -
K 2 SO 4 → 2K + + SO 4 2-
Al(NO3)3 → Al 3+ + 3NO 3 -

1. Metal + non-metal = salt
2Fe + 3Cl 2 = 2FeCl 3

2. Metal + acid = salt + hydrogen
Zn + 2HCl = ZnCl 2 + H 2

3. Metal + salt = another metal + another salt
Fe + CuSO 4 = Cu + FeSO 4

4. Acid + basic (amphoteric) oxide = salt + water
3H 2 SO 4 +Al 2 O 3 =Al 2 (SO 4) 3 + 3H 2 O

5. Acid + base = salt + water
H 2 SO 4 + 2NaOH = Na 2 SO 4 + 2H 2 O
When a polybasic acid is incompletely neutralized with a base, sour salt:
H 2 SO 4 + NaOH = NaHSO 4 + H 2 O
When a polyacid base is incompletely neutralized with an acid, basic salt:
Zn (OH) 2 + HCl = ZnOHCl + H 2 O

6. Acid + salt = another acid + another salt(a stronger acid is used for this reaction)
AgNO 3 + HCl = AgCl + HNO 3
BaCl 2 + H 2 SO 4 = BaSO 4 + 2HCl

7. Basic (amphoteric) oxide + acid = salt + water
CaO + 2HCl = CaCl 2 +H 2 O

8. Basic oxide + acidic oxide = salt
Li 2 O+CO 2 = Li 2 CO 3

9. Acidic oxide + base = salt + water
SO3 + 2NaOH = Na 2 SO 4 + H 2 O

10. Lye + salt = base + other salt
CuSO 4 + 2NaOH = Cu (OH) 2 + Na 2 SO 4

11. Exchange reaction between salts: salt(1) + salt(2) = salt(3) + salt(4)
NaCl + AgNO 3 = Na NO 3 + AgCl

12. Acid salts can be obtained by the action of excess acid on intermediate salts and oxides:
Na 2 SO 4 + H 2 SO 4 = 2NaHSO 4
Li 2O + 2H 2 SO 4 = 2LiHSO 4 + H 2 O

13. Basic salts obtained by carefully adding small amounts of alkalis to solutions of medium salts:
AlCl 3 + 2NaOH = Al(OH) 2 Cl + 2NaCl

1. Salt + alkali = another salt + another base
CuCl 2 + 2KOH = 2KCl + Cu(OH) 2

2. Salt + acid = another salt + another acid
BaCl 2 + H 2 SO 4 = BaSO 4 + 2HCl

3. Salt(1) + salt(2) = Salt(3) + salt(4)
Na 2 SO 4 + BaCl 2 = 2NaCl + BaSO 4

4. Salt + metal = another salt + another metal(according to the electrochemical series of metal voltages)
Zn + Pb(NO 3) 2 = Pb + Zn(NO 3) 2

5. Some salts decompose when heated
CaCO 3 = CaO + CO 2
KNO 3 = KNO 2 + O 2

The specific chemical properties of salts depend on which cation and which anion form a given salt.

Specific properties of salts by cation	Specific properties of salts by anion
Ag + + Cl - = AgCl ↓ white cheesy sediment Cu 2+ + 2OH - = Cu (OH) 2 ↓ blue precipitate Ba 2+ + SO 4 2- = BaSO 4 ↓ white fine-crystalline precipitate Fe 3+ + 3SCN - = Fe (SCN) 3 blood red color Al 3+ + 3OH - = Al (OH) 3 ↓ white jelly-like precipitate Ca2+ + CO 3 2- = CaCO 3 ↓ white precipitate	Ag + + Cl-= AgCl ↓ white cheesy sediment Ba 2+ + SO 4 2-= BaSO 4 ↓ white fine-crystalline precipitate 2H++ SO 3 2-= H 2 O + SO 2 gas with a pungent odor 2H++ CO 3 2-= H 2 O + CO 2 odorless gas 3Ag + + PO 4 3-= Ag 3 PO 4 ↓ yellow precipitate 2H++ S 2-= H 2 S gas with an unpleasant smell of rotten eggs

Task 1. From the list above, select salts, name them, and determine the type.
1) KNO 2 2) LiOH 3) CaS 4) CuSO 4 5) P 2 O 5 6) Al(OH) 2 Cl 7) NaHSO 3 8) H 2 SO 4

Task 2. Which of the following substances can react with a) BaCl 2 b) CuSO 4 c ) Na 2 CO 3 ?
1)Na 2 O 2)HCl 3)H 2 O 4) AgNO 3 5)HNO 3 6)Na 2 SO 4 7)BaCl 2 8)Fe 9)Cu(OH) 2 10) NaOH

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) Anionic 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 average salt anion:
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 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 complex-forming 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 dissociating 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 of 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. Interaction acid oxide and grounds :

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 reacting oxide 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 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 able to combine 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

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