When heated, carbonates (all except alkali metal and ammonium carbonates) decompose to metal oxide and carbon (IV) monoxide. CaCO 3 CaO + CO 2
When heated, ammonium carbonate decomposes into ammonia, water and carbon dioxide:
(NH 4) 2 CO 3 2NH 3 + 2H 2 O + CO 2
When heated, hydrocarbonates turn into carbonates: 2NaHCO 3 Na 2 CO 3 + CO 2 + H 2 O
A qualitative reaction to CO 3 2─ and HCO 3 ions is their interaction with stronger acids, the latter displace carbonic acid from the salts, and it decomposes with the release of CO 2
Na 2 CO 3 + 2HCl = 2NaCl + CO 2 + H 2 O NaHCO 3 + HCl = NaCl + CO 2 + H 2 O
When mixing solutions, hydrolysis will occur at both the weak acid anion and the weak base cation: 3Na 2 CO 3 + 2FeCl 3 + 3H 2 O = 2Fe(OH) 3 + 6NaCl + 3CO 2
Silicon. At low temperatures, silicon is chemically inert; at high temperatures it reacts with both non-metals and some metals. In most cases, silicon is a reducing agent; in reactions with stronger reducing agents (active metals) it acts as an oxidizing agent.
When heated above 400°C, silicon interacts with oxygen: Si + O 2 = SiO 2
When interacting with halogens (with fluorine at room temperature), when heated with chlorine, bromine, iodine, silicon halides are formed:
Si + 2Cl 2 = SiCl 4 Si + 2Br 2 = SiBr 4
At temperatures above 600°C it interacts with sulfur: Si + 2S = SiS 2
At a temperature of about 2000°C, silicon combines with carbon to form silicon carbide (carborundum): Si + C = SiC
When interacting with active metals, metal silicides are formed: Si + 2Mg = Mg 2 Si
Si + 2Ca = Ca 2 Si Si + 2MgO = Mg 2 Si + 2SiO
Silicides of alkali, alkaline earth metals and magnesium decomposes with water, alkalis and dilute acids to form silane:
Mg 2 Si + 4H 2 O = 2Mg(OH) 2 + SiH 4 Mg 2 Si + 4HCl = 2MgCl 2 + SiH 4
2Ca 2 Si + 4NaOH + 10H 2 O = 2Na 2 SiO 3 + 4Ca(OH) 2 + SiH 4
In aqueous solutions of alkalis, silicon dissolves to form silicic acid salts:
Si + 2NaOH + H 2 O = Na 2 SiO 3 + 2H 2
Silicon does not interact with aqueous solutions of acids, but amorphous silicon dissolves in hydrofluoric acid: Si + 6HF = H 2 + 2H 2 (Si (solid) + 4HF (g) = SiF 4 + 2H 2)
Silicon dissolves in a mixture of concentrated nitric and hydrofluoric acids:
3Si + 4HNO 3 + 12HF = 3SiF 4 + 4NO + 8H 2 O
Silicon(IV) oxide. As an acidic oxide, SiO 2, when fused, reacts with solid alkalis, basic oxides and carbonates to form silicic acid salts (silicates):
SiO 2 + 2KOH K 2 SiO 3 + H 2 O (alkali solutions also act on SiO 2)
SiO 2 + CaO CaCO 3 SiO 2 + K 2 CO 3 K 2 SiO 3 + CO 2
Interacts with hydrofluoric acid: SiO 2 + 6HF = H 2 + 2H 2 O
When a mixture of SiO 2 and carbon is heated, silicon carbide is formed: SiO 2 + 3C SiC + 2CO
SiO 2 + 2Mg 2MgO + Si 3SiO 2 + Ca 3 (PO 4) 2 + 5C 3CaSiO 3 + 5CO + 2P
Silan- poisonous colorless gas. In air, silane burns to form SiO 2 and H 2 O, and decomposes with water and alkalis to release hydrogen: SiH 4 + 2O 2 = SiO 2 + 2H 2 O
SiH 4 + 2H 2 O = SiO 2 + 4H 2 SiH 4 + 2NaOH + H 2 O = Na 2 SiO 3 + 4H 2
Silicon tetrachloride.
SiCl 4 + 3H 2 O = H 2 SiO 3 ↓ + 4HCl SiCl 4 + 2H 2 = Si + 4HCl
1. The gases that are released when coal is heated in concentrated nitric and sulfuric acids are mixed with each other. The reaction products were passed through lime milk
2. Quicklime was “quenched” with water. Gas was passed into the resulting solution, which is released when sodium bicarbonate is heated, and the formation and subsequent dissolution were observed.
3. The gas formed during the combustion of coke was in contact with hot coal for a long time. The reaction product was passed successively through a layer of iron ore and quicklime.
4. One of the substances formed when silicon oxide fuses with magnesium dissolves in alkali. The released gas was reacted with sulfur, and the product of their interaction was treated with chlorine.
5. Magnesium silicide was treated with a solution of hydrochloric acid and the resulting gas was burned. The solid reaction product was mixed with soda ash, the mixture was heated until melting and kept for some time. After cooling, the reaction product (used as “liquid glass”) was dissolved in water and treated with a sulfuric acid solution.
6. Silicon (IV) chloride was heated in a mixture with hydrogen. The reaction product was mixed with magnesium powder, heated and treated with water, one of the resulting substances spontaneously ignites in air
7. Magnesium silicide was treated with a solution of hydrochloric acid, the reaction product was burned, the resulting solid was mixed with soda ash and heated until melting. After cooling the melt, it was treated with water and nitric acid was added to the resulting solution.
8. Magnesium powder was mixed with silicon and heated. The reaction product was treated with cold water, and the resulting gas was passed through hot water. The resulting precipitate was separated, mixed with caustic soda and heated until melting.
9. Silicon was burned in a chlorine atmosphere. The resulting chloride was treated with water. the precipitate released was calcined. Then fused with calcium phosphate and coal.
10. The substance formed by the fusion of magnesium with silicon was treated with water, as a result, a colorless gas was formed and released. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate, which resulted in the formation of two water-insoluble binary substances.
11. The product of the interaction of silicon with chlorine is easily hydrolyzed. When the solid hydrolysis product is fused with both caustic and soda ash, liquid glass is formed.
12. Carbon was burned in excess oxygen, the resulting gas was passed over copper (II) oxide. The resulting substance was fused with sulfur, and the product of this reaction was burned in oxygen.
13. Silicon was burned in oxygen. The reaction product was fused with sodium carbonate, and the resulting substance was treated with excess hydrochloric acid while heating. The precipitate was filtered, and a solution of silver nitrate was added to the filtrate.
14. Silicon was dissolved in a concentrated solution of sodium hydroxide. Carbon dioxide was passed through the resulting solution. The precipitate that formed was filtered, dried and divided into two parts. The first was dissolved in hydrofluoric acid, the second was fused with magnesium.
1. C + 2H 2 SO 4 (conc.) = CO 2 + 2SO 2 + 2H 2 O C + 4HNO 3 (conc.) = CO 2 + 4NO 2 + 2H 2 O
SO 2 + NO 2 = SO 3 + NO SO 3 + Ca(OH) 2 = CaSO 4 ↓ + H 2 O + CO 2
Ca(OH) 2 = CaCO 3 ↓ + H 2 O
2. CaO + H 2 O = Ca(OH) 2 2NaHCO 3 Na 2 CO 3 + CO 2 + H 2 O
CO 2 + Ca(OH) 2 = CaCO 3 ↓ + H 2 O CaCO 3 + CO 2 + H 2 O = Ca(HCO 3) 2
3. C + O 2 = CO 2 CO 2 + C = 2CO
Fe 2 O 3 + 3CO = 2Fe + 3CO 2 or Fe 3 O 4 + 4CO = 3Fe + 4CO 2
CaO + CO 2 = CaCO 3
4. 2C + O 2 = 2CO CO + CuO = Cu + CO 2
Cu + S = CuS 2CuS + 3O 2 = 2CuO + 2SO 2
5. SiO 2 + 2Mg = 2MgO + Si Si + 2NaOH + 2H 2 O = Na 2 SiO 3 + 2H 2
H 2 + S = H 2 S H 2 S + Cl 2 = 2HCl + S↓
6. Mg 2 Si + 4HCl = 2MgCl 2 + 2SiH 4 SiH 4 + 2O 2 = SiO 2 + 2H 2 O
SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2 Na 2 SiO 3 + H 2 SO 4 = Na 2 SO 4 + H 2 SiO 3 ↓
7. SiCl 4 + 2H 2 = Si + 4HCl Si + 2Mg = Mg 2 Si
Mg 2 Si + 4H 2 O = 2Mg(OH) 2 ↓ + SiH 4 SiH 4 + 2O 2 = SiO 2 ↓ + 2H 2 O
8. Mg 2 Si + 4HCl = 2MgCl 2 + 2SiH 4 SiH 4 + 2O 2 = SiO 2 + 2H 2 O
SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2 Na 2 SiO 3 + 2HNO 3 = 2NaNO 3 + H 2 SiO 3 ↓
9. Si + 2Mg = Mg 2 Si Mg 2 Si + 4H 2 O (cold) = 2Mg(OH) 2 ↓ + SiH 4
SiH 4 + 2H 2 O (hor.) = SiO 2 + 4H 2 SiO 2 + 2NaOH = Na 2 SiO 3 + H 2 O
10. Si + 2Cl 2 = SiCl 4 SiCl 4 + 3H 2 O = H 2 SiO 3 ↓ + 4HCl
H 2 SiO 3 SiO 2 + H 2 O 3SiO 2 + Ca 3 (PO 4) 2 + 5C 3CaSiO 3 + 5CO + 2P
11. Si + 2Mg = Mg 2 Si Mg 2 Si + 4H 2 O (cold) = 2Mg(OH) 2 ↓ + SiH 4
Mg(OH) 2 + 2HCl = MgCl 2 + 2H 2 O SiH 4 + 8KMnO 4 = 8MnO 2 ↓ + 3SiO 2 ↓ + 8KOH + 2H 2 O
12. Si + 2Cl 2 = SiCl 4 SiCl 4 + 2H 2 O = SiO 2 ↓ + 4HCl
SiO 2 + 2NaOH = Na 2 SiO 3 + H 2 O SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2
13. Si + O 2 = SiO 2 SiO 2 + Na 2 CO 3 = Na 2 SiO 3 + CO 2
Na 2 SiO 3 + 2HCl = 2NaCl + SiO 2 ↓ + H 2 O NaCl + AgNO 3 = AgCl↓ + NaNO 3
14. Si + 2NaOH + 2H 2 O = Na 2 SiO 3 + 2H 2 Na 2 SiO 3 + CO 2 = Na 2 CO 3 + SiO 2 ↓
SiO 2 + 4HF = SiF 4 + 2H 2 O SiO 2 + 2Mg = Si + 2MgO
Nitrogen. Nitrogen compounds.
Nitrogen in the laboratory obtained by the decomposition of ammonium nitrite:
NH 4 NO 2 N 2 + 2H 2 O NaNO 2 + NH 4 Cl N 2 + NaCl + 2H 2 O
Under normal conditions, nitrogen does not react with metals (with the exception of lithium - N2 reacts with it at room temperature) or with non-metals. When heated, the chemical activity of nitrogen increases.
When interacting with metals, metal nitrides are formed:
N 2 + 6 Li = 2Li 3 N N 2 + 6 Na 2Na 3 N
N 2 + 3Mg Mg 3 N 2 N 2 + 2Al (powder) 2AlN
Nitrides of alkali and alkaline earth metals are easily decomposed by water and acid solutions:
Li 3 N + 3H 2 O = 3LiOH + NH 3 Ca 3 N 2 + 6HCl = 3CaCl 2 + 2NH 3
Nitrogen interacts with non-metals only under special conditions - at high temperature, pressure, in the presence of a catalyst, or when passing a strong electric discharge:
N2 + 3H2 
2NH 3 N 2 + O 2 
2NO N 2 + 3LiH Li 3 N + NH 3
Ammonia. Ammonia reacts most vigorously with chlorine and bromine, oxides of some metals, and also (when the mixture is ignited or in the presence of a catalyst) with oxygen:
2NH 3 + 3Cl 2 = N 2 + 6HCl 2NH 3 + 3CuO = 3Cu + N 2 + 3H 2 O
4NH 3 + 3O 2 = 2N 2 + 6H 2 O 4NH 3 + 5O 2 4NO + 6H 2 O
Hydrogen peroxide also oxidizes ammonia to nitrogen: 2NH 3 + 3H 2 O 2 = N 2 + 6H 2 O
Due to hydrogen atoms in the +1 oxidation state, ammonia can act as an oxidizing agent, for example in reactions with alkali, alkaline earth metals, magnesium and aluminum:
2NH 3 + 2Na = 2NaNH 2 + H 2 (Na 2 NH, Na 3 N) 2NH 3 + 2Al = 2AlN + 3H 2
The dissolution of ammonia in water is accompanied by chemical interaction with it:
NH 3 + H 2 O ↔ NH 3 ∙ H 2 O ↔ NH 4 + + OH −
When interacting with acids, ammonium salts are formed:
NH 3 + HCl = NH 4 Cl NH 3 + H 2 SO 4 = NH 4 HSO 4 2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4
When ammonia reacts with carbon dioxide, carbamide (urea) is formed:
2NH 3 + CO 2 = (NH 2) 2 CO + H 2 O
Ammonia enters into complexation reactions:
6NH 3 + CuCl 2 = Cl 2 4NH 3 + Cu(OH) 2 = (OH) 2
Ammonium salts. All ammonium salts exhibit the general properties of salts (they interact with solutions of acids, alkalis and other salts), and also undergo hydrolysis and decompose when heated:
NH 4 Cl + KOH = KCl + NH 3 + H 2 O (qualitative reaction to NH 4 +)
(NH 4) 2 SO 4 + Ba(NO 3) 2 = 2NH 4 NO 3 + BaSO 4 ↓ NH 4 HS + 3HNO 3 = S + 2NO 2 + NH 4 NO 3 + 2H 2 O
If the salt does not contain an oxidizing anion, then decomposition occurs without changing the oxidation state of the nitrogen atom: NH 4 Cl NH 3 + HCl NH 4 HCO 3 NH 3 + CO 2 + H 2 O
(NH 4) 2 SO 4 NH 4 HSO 4 + NH 3 NH 4 HS NH 3 + H 2 S
If the salt contains an oxidizing anion, then the decomposition is accompanied by a change in the oxidation state of the nitrogen atom of the ammonium ion: NH 4 NO 2 N 2 + 2H 2 O NH 4 NO 3 = N 2 O + 2H 2 O (190 – 245 ° C)
2NH 4 NO 3 = 2NO + 4H 2 O (250 – 300° C) 2NH 4 NO 3 = 2N 2 + O 2 + 4H 2 O (above 300° C)
(NH 4) 2 Cr 2 O 7 Cr 2 O 3 + N 2 + 4H 2 O
Nitrogen oxides. Under normal conditions N2O chemically inert, when heated it exhibits the properties of an oxidizing agent:
N 2 O + H 2 = N 2 + H 2 O N 2 O + Mg = N 2 + MgO
N 2 O + 2Cu = N 2 + Cu 2 O 3N 2 O + 2NH 3 = 4N 2 + 3H 2 O
N 2 O + H 2 O + SO 2 = N 2 + H 2 SO 4
When interacting with strong oxidizing agents, N 2 O can exhibit the properties of a reducing agent:
5N 2 O + 3H 2 SO 4 + 2KMnO 4 = 10NO + 2MnSO 4 + K 2 SO 4 + 3H 2 O
NO poisonous! In the laboratory it is obtained by reacting 30% nitric acid with certain metals: 3Cu + 8HNO 3 = 3Cu(NO 3) 2 + 2NO + 4H 2 O
NO can also be obtained by the reactions: FeCl 2 + NaNO 3 + 2HCl = FeCl 3 + NaCl + NO + H 2 O
2HNO3 + 2HI = 2NO + I2 + 2H2O
In air, NO is almost instantly oxidized to NO 2: 2NO + O 2 = 2NO 2
In relation to halogens, NO also exhibits the properties of a reducing agent:
2NO + Cl 2 = 2NOCl NO + O 3 = NO 2 + O 2
In the presence of stronger reducing agents, it exhibits the properties of an oxidizing agent:
2NO + 2H 2 = N 2 + 2H 2 O 2NO + 2SO 2 = 2SO 3 + N 2
N2O3 Acidic oxide. Nitrous acid anhydride. When interacting with water, it produces nitrous acid: N 2 O 3 + H 2 O ↔ 2HNO 2
When interacting with alkali solutions, nitrites are formed: N 2 O 3 + 2NaOH = 2NaNO 2 + H 2 O
NO 2 Very poisonous! NO 2 is characterized by high chemical activity: it interacts with non-metals (phosphorus, coal, sulfur burn in nitrogen oxide (IV), sulfur oxide (IV) is oxidized to sulfur oxide VI)). In these reactions, NO 2 is the oxidizing agent: 2NO 2 + 2S = N 2 + 2SO 2 2NO 2 + 2C = N 2 + 2CO 2
10NO 2 + 8P = 5N 2 + 4P 2 O 5 NO 2 + SO 2 = SO 3 + NO
Dissolution of NO 2 in water leads to the formation of nitric and nitrous acids:
2NO 2 + H 2 O = HNO 3 + HNO 2
Since nitrous acid is unstable, when NO 2 is dissolved in warm water, HNO 3 and NO are formed:
3NO 2 + H 2 O = 2HNO 3 + NO When heated: 4NO 2 + 2H 2 O = 4HNO 3 + O 2
If NO 2 is dissolved in water in an excess of oxygen, then only nitric acid is formed:
4NO 2 + 2H 2 O + O 2 = 4HNO 3
When dissolved in alkalis - nitrates and nitrites:
2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 4NO 2 + 2Ca(OH) 2 = Ca(NO 2) 2 + Ca(NO 3) 2 + 2H 2 O
In the presence of oxygen - nitrates: 4NO 2 + 4NaOH + O 2 = 4NaNO 3 + 2H 2 O
N2O5 Acidic oxide. Nitric anhydride. Dissolves in water to form nitric acid:
N 2 O 5 + H 2 O = 2HNO 3, in alkalis - with the formation of nitrates: N 2 O 5 + 2NaOH = 2NaNO 3 + H 2 O
HNO 2 Nitrous acid exists only in dilute solutions, when heated it decomposes: 3HNO 2 ↔ HNO 3 + 2NO + H 2 O
Since the oxidation state of nitrogen in HNO 2 is +3, nitrous acid exhibits both oxidizing and reducing properties:
2HNO 2 + 2HI = 2NO + I 2 + 2H 2 O 5HNO 3 + 2HMnO 4 = 2Mn(NO 3) 2 + HNO 3 + 3H 2 O
HNO 2 + Cl 2 + H 2 O = HNO 3 + 2HCl 2HNO 2 + O 2 = 2HNO 3
HNO 2 + H 2 O 2 = HNO 3 + H 2 O 2HNO 2 + 3H 2 SO 4 + 6FeSO 4 = 3Fe 2 (SO 4) 3 + N 2 + 4H 2 O
HNO 3 Nitric acid when boiling (t boiling point = 85°C) and upon prolonged standing, it partially decomposes:
4HNO 3 4NO 2 + O 2 + 2H 2 O
Nitric acid exhibits very high chemical activity. The oxidation state of nitrogen in HNO 3 is +5, so nitric acid is an oxidizing agent, and a very strong one at that. Depending on the conditions (nature of the reducing agent, concentration of HNO 3 and temperature), the oxidation state of the nitrogen atom in the reaction products can vary from +4 to −3: NO 2, NO, N 2 O, N 2, NH 4 +
The higher the concentration of nitric acid, the fewer electrons the NO 3 − anion is inclined to accept.
Interaction with metals. Concentrated HNO 3 does not react with aluminum, chromium and iron in the cold - the acid “passivates” the metals, because a film of oxides forms on their surface, impermeable to concentrated nitric acid. When heated, the reaction occurs:
Fe + 6HNO 3 (conc.) Fe(NO 3) 3 + 3NO 2 + 3H 2 O Al + 6HNO 3 (conc.) Al(NO 3) 3 + 3NO 2 + 3H 2 O
Gold and platinum are dissolved in “aqua regia” - a mixture of concentrated nitric and hydrochloric acids in a ratio of 1: 3 (by volume) HNO 3 + 3HCl + Au = AuCl 3 + NO + 2H 2 O
4HNO 3(conc.) + Cu = Cu(NO 3) 2 + 2NO 2 + 2H 2 O 8HNO 3(diluted) +3Cu=3Cu(NO 3) 2 +2NO+ H 2 O
4HNO 3 (60%) + Zn = Zn(NO 3) 2 + 2NO 2 + 2H 2 O 8HNO 3 (30%)+3Zn=3Zn(NO 3) 2 +2NO+4H 2 O 10HNO 3 (20%) + 4Zn = 4Zn(NO 3) 2 + 2N 2 O + 5H 2 O 10HNO 3 (3%) + 4Zn = 4Zn(NO 3) 2 + NH 4 NO 3 + 3H 2 O
When interacting with non-metals, HNO 3 is usually reduced to NO or NO 2, non-metals are oxidized to the corresponding acids: 6HNO 3 + S = H 2 SO 4 + 6NO 2 + 2H 2 O 5HNO 3 + P = H 3 PO 4 + 5NO 2 + H 2 O 5HNO 3 + 3P + 2H 2 O = 3H 3 PO 4 + 5NO 4HNO 3 + C = CO 2 + 4NO 2 + 2H 2 O 10HNO 3 + I 2 = 2HIO 3 + 10NO 2 + 4H 2 O
HNO 3 can also exhibit properties as an oxidizing agent in reactions with complex substances:
6HNO 3 + HI = HIO 3 + 6NO 2 + 3H 2 O 2HNO 3 + SO 2 = H 2 SO 4 + 2NO 2
2HNO 3 + H 2 S = S + 2NO 2 + 2H 2 O 8HNO 3 + CuS = CuSO 4 + 8NO 2 + 4H 2 O
4HNO 3 + FeS = Fe(NO 3) 3 + NO + S + 2H 2 O
Nitrous acid salts nitrites more stable than the acid itself, and they are all poisonous. Since the oxidation state of nitrogen in nitrites is +3, they exhibit both oxidizing and reducing properties:
2KNO 2 + O 2 = 2KNO 3 KNO 2 + H 2 O 2 = KNO 3 + H 2 O
KNO 2 + H 2 O + Br 2 = KNO 3 + 2HBr 5KNO 2 + 3H 2 SO 4 + 2KMnO 4 = 5KNO 3 + 2MnSO 4 + K 2 SO 4 + 3H 2 O
3KNO 2 + 4H 2 SO 4 + K 2 Cr 2 O 7 = 3KNO 3 + Cr 2 (SO 4) 3 + K 2 SO 4 + 4H 2 O
2KNO 2 + 2H 2 SO 4 + 2KI = 2NO + I 2 + 2K 2 SO 4 + 2H 2 O 3KNO 2 + Cr 2 O 3 + KNO 3 = 2K 2 CrO 4 + 4NO
Salts of nitric acid - nitrates are thermally unstable, and they all decompose into oxygen and a compound, the nature of which depends on the position of the metal (part of the salt) in the series of metal stresses:
1) Salts of alkali and alkaline earth metals (up to Mg) decompose to nitrite and oxygen:
2NaNO 3 2NaNO 2 + O 2
2) Salts of heavy metals (from Mg to Cu) – to metal oxide, nitrogen oxide (IV) and oxygen:
2Cu(NO 3) 2 2CuO + 4NO 2 + O
3) Salts of low-active metals (to the right of Cu) - to metal, nitrogen oxide (IV) and oxygen
2AgNO 3 2Ag + 2NO 2 + O 2
A mixture of 75% KNO 3, 15% C and 10% S is called “black powder” 2KNO 3 + 3C + S = N 2 + 3CO 2 + K 2 S + Q
1. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of a low-active colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by reacting magnesium nitride with water.
2. Electrical discharges were passed over the surface of a caustic soda solution poured into a flask, and the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and it was determined that the solid residue was a mixture of two salts. When this mixture is heated, gas is released and the only substance remains.
3. As a result of the thermal decomposition of ammonium dichromate, a gas was obtained, which was passed over heated magnesium. The resulting substance was placed in water. The resulting gas was passed through freshly precipitated copper (II) hydroxide.
4. The gas released at the anode during the electrolysis of mercury (II) nitrate was used for the catalytic oxidation of ammonia. The resulting colorless gas instantly reacted with oxygen in the air. The resulting brown gas was passed through barite water.
5. Iodine was placed in a test tube with concentrated hot nitric acid. The released gas was passed through water in the presence of oxygen. Copper(II) hydroxide was added to the resulting solution. The resulting solution was evaporated and the dry solid residue was calcined.
6. The product of the reaction of lithium with nitrogen was treated with water. The resulting gas was passed through a solution of sulfuric acid until the chemical reactions stopped. The resulting solution was treated with barium chloride. The solution was filtered, and the filtrate was mixed with sodium nitrite solution and heated.
7. A sample of aluminum was dissolved in dilute nitric acid, and a simple substance was released. Sodium carbonate was added to the resulting solution until gas evolution completely stopped. The precipitate that formed was filtered and calcined, the filtrate was evaporated, and the resulting solid residue was fused with ammonium chloride. The released gas was mixed with ammonia and the resulting mixture was heated.
8. Two salts contain the same cation. The thermal decay of the first of them resembles a volcanic eruption, with the release of a low-active colorless gas that is part of the atmosphere. When the second salt interacts with a solution of silver nitrate, a white cheesy precipitate is formed, and when it is heated with an alkali solution, a colorless poisonous gas with a pungent odor is released; this gas can also be obtained by reacting magnesium nitride with water.
9. Electrical discharges were passed over the surface of a caustic soda solution poured into a flask, and the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and it was determined that the solid residue was a mixture of two salts. When this mixture is heated, gas is released and the only substance remains.
10. A mixture of two colorless, colorless and odorless gases A and B was passed through when heated over a catalyst containing iron, and the resulting gas B was neutralized with a solution of hydrobromic acid. The solution was evaporated and the residue was heated with caustic potassium, resulting in the release of colorless gas B with a pungent odor. When gas B is burned in air, water and gas A are formed.
11. Nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was added to a solution acidified with sulfuric acid with potassium permanganate, and the solution became colorless. The nitrogen-containing reaction product was placed in a solution of caustic soda and zinc dust was added, and a gas with a sharp characteristic odor was released.
12. The nitrogen-hydrogen mixture was heated to a temperature of 500º C and passed under high pressure over an iron catalyst. The reaction products were passed through a solution of nitric acid until it was neutralized. The resulting solution was carefully evaporated, the solid residue was calcined and the gas released was passed over copper while heating, resulting in the formation of a black substance.
13. The product of the interaction of nitrogen and lithium was treated with water. The gas released as a result of the reaction was mixed with excess oxygen and, when heated, passed over a platinum catalyst; the resulting gas mixture was brown in color.
14. A gas mixture of ammonia and a large excess of air was passed through when heated over platinum and the reaction products were absorbed after some time by a solution of sodium hydroxide. After evaporation of the solution, a single product was obtained.
15. Brown gas was passed through an excess of caustic potassium solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated; The released gas neutralized nitric acid. The resulting solution was carefully evaporated, and the solid reaction product was calcined.
16. Copper (I) oxide was treated with concentrated nitric acid, the solution was carefully evaporated and the solid residue was calcined. The gaseous reaction products were passed through a large amount of water and magnesium shavings were added to the resulting solution, resulting in the release of a gas used in medicine.
17. Magnesium nitride was treated with excess water. When the released gas is passed through bromine water or through a neutral solution of potassium permanganate, and when it is burned, the same gaseous product is formed.
18. One of the products of the interaction of ammonia with bromine, a gas that is part of the atmosphere, was mixed with hydrogen and heated in the presence of platinum. The resulting mixture of gases was passed through a solution of hydrochloric acid and potassium nitrite was added to the resulting solution with slight heating.
19. Magnesium was heated in a vessel filled with ammonia gas. The resulting substance was dissolved in a concentrated solution of hydrobromic acid, the solution was evaporated and the residue was heated until an odor appeared, after which an alkali solution was added.
20. A mixture of nitrogen and hydrogen was successively passed over heated platinum and through a solution of sulfuric acid. Barium chloride was added to the solution and, after separating the precipitate that formed, milk of lime was added and heated.
21. Ammonia was mixed with a large excess of air, heated in the presence of platinum and after some time absorbed by water. Copper shavings added to the resulting solution dissolve with the release of brown gas.
22. When an orange substance is heated, it decomposes; Decomposition products include a colorless gas and a green solid. The released gas reacts with lithium even with slight heating. The product of the latter reaction reacts with water, releasing a gas with a pungent odor that can reduce metals, such as copper, from their oxides.
23. Calcium metal was calcined in a nitrogen atmosphere. The reaction product was treated with water, and the resulting gas was passed into a solution of chromium (III) nitrate. The gray-green precipitate that formed during the process was treated with an alkaline solution of hydrogen peroxide.
24. A mixture of potassium nitrite and ammonium chloride powders was dissolved in water and the solution was gently heated. The released gas reacted with magnesium. The reaction product was added to an excess of hydrochloric acid solution, and no gas evolution was observed. the resulting magnesium salt in solution was treated with sodium carbonate.
25. Copper was dissolved in concentrated nitric acid. An excess of ammonia solution was added to the resulting solution, first the formation of a precipitate was observed, and then its complete dissolution. The resulting solution was treated with excess hydrochloric acid.
26. Magnesium was dissolved in dilute nitric acid, and no gas evolution was observed. The resulting solution was treated with an excess of potassium hydroxide solution while heating. The gas released was burned in oxygen.
27. Potassium nitrite was heated with powdered lead until the reaction stopped. The mixture of products was treated with water, and then the resulting solution was filtered. The filtrate was acidified with sulfuric acid and treated with potassium iodide. The isolated simple substance was heated with concentrated nitric acid. Red phosphorus was burned in the atmosphere of the resulting brown gas.
28. The gas formed by the interaction of nitrogen and hydrogen was divided into two parts. The first was passed over hot copper (II) oxide, the second was burned in oxygen in the presence of a catalyst. The resulting gas in excess oxygen turned into a brown gas.
29. Dilute nitric acid reacted with magnesium to release a colorless gas. Graphite was burned in its atmosphere to form simple and complex substances. When heated, the simple substance reacted with calcium, and the complex substance reacted with an excess of sodium hydroxide solution.
30. Ammonia was absorbed with nitric acid, and the resulting salt was heated until only two oxides were formed. One of them reacted with sodium, and the second reacted with copper at high temperature.
31. Nitric oxide (II) was oxidized with oxygen. The reaction product was absorbed into a solution of potassium hydroxide, and oxygen was passed through the resulting solution until only one salt was formed.
32. Calcium was burned in a nitrogen atmosphere. The resulting substance was dissolved in boiling water. The released gas was burned in oxygen in the presence of a catalyst, and a solution of hydrochloric acid was added to the suspension.
33. When heated on a catalyst, nitrogen reacted with hydrogen. The resulting gas was absorbed in a solution of nitric acid, evaporated to dryness, and the resulting crystalline substance was divided into two parts. The first one was decomposed at a temperature of 190 – 240°C, with the formation of only one gas and water vapor. The second part was heated with a concentrated solution of sodium hydroxide.
1)(NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O NH 4 Cl + AgNO 3 = AgCl↓ + NH 4 NO 3
NH 4 Cl + NaOH = NaCl + NH 3 + H 2 O Mg 3 N 2 + 6H 2 O = 3Mg(OH) 2 ↓ + 2NH 3
2)N 2 + O 2 
2NO 2NO + O 2 = 2NO 2
NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 3 2NaNO 2 + O 2
3) (NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O 3Mg + N 2 = Mg 3 N 2
Mg 3 N 2 + 6H 2 O = 3Mg(OH) 2 ↓ + 2NH 3 4NH 3 + Cu(OH) 2 = (OH) 2
4) 2Hg(NO 3) 2 + 2H 2 O 
2Hg + O 2 + 4HNO 3 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2 4NO 2 + 2Ba(OH) 2 = Ba(NO 3) 2 + Ba(NO 2) 2 + 2H 2 O
5) I 2 + 10HNO 3 = 2HIO 3 + 10NO 2 + 4H 2 O 4NO 2 + O 2 + 2H 2 O = 4HNO 3
2HNO 3 + Cu(OH) 2 = Cu(NO 3) 2 + 2H 2 O 2Cu(NO 3) 2 2CuO + O 2 + 4NO 2
6) 6Li + N 2 = 2Li 3 N Li 3 N + 3H 2 O = 3LiOH + NH 3
2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4 (NH 4) 2 SO 4 + BaCl 2 = BaSO 4 + 2NH 4 Cl
NH 4 Cl + NaNO 2 N 2 + NaCl + 2H 2 O
7) 10Al + 36HNO 3 = 10Al(NO 3) 3 + 3N 2 + 18H 2 O 2Al(NO 3) 3 + 3Na 2 CO 3 + 3H 2 O = 2Al(OH) 3 ↓+ 3CO 2 + 6NaNO 3
2Al(OH) 3 Al 2 O 3 + 3H 2 O NaNO 3 + NH 4 Cl N 2 O + NaCl + 2H 2 O 3N 2 O + 2NH 3 = 4N 2 + 3H 2 O
8) (NH 4) 2 Cr 2 O 7 N 2 + Cr 2 O 3 + 4H 2 O NH 4 Cl + AgNO 3 = AgCl↓ + NH 4 NO 3
NH 4 Cl + NaOH = NaCl + NH 3 + H 2 O Mg 3 N 2 + 6H 2 O = 2NH 3 + 3Mg(OH) 2 ↓
9) N 2 + O 2 
2NO 2NO + O 2 = 2NO 2
2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 3 2NaNO 2 + O 2
10) N 2 + 3H 2 = 2NH 3 NH 3 + HBr = NH 4 Br
NH 4 Br + KOH = KBr + H 2 O + NH 3 4NH 3 + 3O 2 = 2N 2 + 6H 2 O
11) HNO 3 + NaHCO 3 = NaNO 3 + H 2 O + CO 2 2NaNO 3 2NaNO 2 + O 2
5NaNO 2 + 2KMnO 4 + 3H 2 SO 4 = 5NaNO 3 + K 2 SO 4 + 2MnSO 4 + 3H 2 O
NaNO 3 + 4Zn + 7NaOH + 6H 2 O = NH 3 + 4Na 2
12) N 2 + 3H 2 ↔ 2NH 3 NH 3 + HNO 3 = NH 4 NO 3
NH 4 NO 3 N 2 O + 2H 2 O N 2 O + Cu = CuO + N 2
13) N 2 + 6Li = 2Li 3 N Li 3 N + 3H 2 O = 3LiOH + NH 3
4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2
14) 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2
2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O 2NaNO 2 + O 2 = 2NaNO 3
15) 2NO 2 + O 2 + 2KOH = 2KNO 3 + H 2 O KNO 3 + 4Mg + 6H 2 O = NH 3 + 4Mg(OH) 2 ↓+ KOH
NH 3 + HNO 3 = NH 4 NO 3 NH 4 NO 3 N 2 O + 2H 2 O
16) Cu 2 O + 6HNO 3 = 2Cu(NO 3) 2 + 2NO 2 + 3H 2 O 2Cu(NO 3) 2 2CuO + 4NO 2 + O 2
4NO 2 + O 2 + 2H 2 O = 4HNO 3 4Mg + 10HNO 3(dil.) = 4Mg(NO 3) 2 + N 2 O+ 5H 2 O
or 4Mg + 10HNO 3(ultra dil.) = 4Mg(NO 3) 2 + NH 4 NO 3 + 3H 2 O
17) Mg 3 N 2 + 6H 2 O = 3Mg(OH) 2 ↓ + 2NH 3 2NH 3 + 3Br 2 = N 2 + 6HBr or
2KMnO 4 + 2NH 3 = 2MnO 2 + N 2 + 3KOH + 3H 2 O 4NH 3 + 3O 2 = 2N 2 + 6H 2 O
18) 2NH 3 + 3Br 2 = N 2 + 6HBr or 8NH 3 + 3Br 2 = N 2 + 6NH 4 Br
N 2 + 3H 2 ↔ 2NH 3 NH 3 + HCl = NH 4 Cl
19) 2NH 3 + 3Mg = Mg 3 N 2 + 3H 2 Mg 3 N 2 + 8HBr = 3MgBr 2 + 2NH 4 Br
NH 4 Br NH 3 + HBr MgBr 2 + 2NaOH = Mg(OH) 2 ↓ + 2NaBr
20) N 2 + 3H 2 = 2NH 3 2NH 3 + H 2 SO 4 = (NH 4) 2 SO 4
(NH 4) 2 SO 4 + BaCl 2 = 2NH 4 Cl + BaSO 4 ↓ 2NH 4 Cl + Ca(OH) 2 = CaCl 2 + 2NH 3 + 3H 2 O
21) 4NH 3 + 5O 2 4NO + 6H 2 O 2NO + O 2 = 2NO 2
4NO 2 + O 2 + 2H 2 O = 4HNO 3 Cu + 4HNO 3 (conc.
Alkali metals react easily with non-metals:
2K + I 2 = 2KI
2Na + H 2 = 2NaH
6Li + N 2 = 2Li 3 N (the reaction occurs at room temperature)
2Na + S = Na 2 S
2Na + 2C = Na 2 C 2
In reactions with oxygen, each alkali metal shows its own individuality: when burned in air, lithium forms an oxide, sodium - peroxide, potassium - superoxide.
4Li + O 2 = 2Li 2 O
2Na + O 2 = Na 2 O 2
K + O 2 = KO 2
Preparation of sodium oxide:
10Na + 2NaNO 3 = 6Na 2 O + N 2
2Na + Na 2 O 2 = 2Na 2 O
2Na + 2NaON = 2Na 2 O + H 2
Interaction with water leads to the formation of alkali and hydrogen.
2Na + 2H 2 O = 2NaOH + H 2
Interaction with acids:
2Na + 2HCl = 2NaCl + H2
8Na + 5H 2 SO 4 (conc.) = 4Na 2 SO 4 + H 2 S + 4H 2 O
2Li + 3H 2 SO 4 (conc.) = 2LiHSO 4 + SO 2 + 2H 2 O
8Na + 10HNO 3 = 8NaNO 3 + NH 4 NO 3 + 3H 2 O
When interacting with ammonia, amides and hydrogen are formed:
2Li + 2NH 3 = 2LiNH 2 + H 2
Interaction with organic compounds:
H ─ C ≡ C ─ H + 2Na → Na ─ C≡C ─ Na + H 2
2CH 3 Cl + 2Na → C 2 H 6 + 2NaCl
2C 6 H 5 OH + 2Na → 2C 6 H 5 ONa + H 2
2CH 3 OH + 2Na → 2 CH 3 ONa + H 2
2СH 3 COOH + 2Na → 2CH 3 COOOONa + H 2
A qualitative reaction to alkali metals is the coloring of the flame by their cations. Li + ion colors the flame carmine red, Na + ion – yellow, K + – violet.
Alkali metal compounds
Oxides.
Alkali metal oxides are typical basic oxides. They react with acidic and amphoteric oxides, acids, and water.
3Na 2 O + P 2 O 5 = 2Na 3 PO 4
Na 2 O + Al 2 O 3 = 2NaAlO 2
Na 2 O + 2HCl = 2NaCl + H 2 O
Na 2 O + 2H + = 2Na + + H 2 O
Na 2 O + H 2 O = 2NaOH
Peroxides.
2Na 2 O 2 + CO 2 = 2Na 2 CO 3 + O 2
Na 2 O 2 + CO = Na 2 CO 3
Na 2 O 2 + SO 2 = Na 2 SO 4
2Na 2 O + O 2 = 2Na 2 O 2
Na 2 O + NO + NO 2 = 2NaNO 2
2Na 2 O 2 = 2Na 2 O + O 2
Na 2 O 2 + 2H 2 O (cold) = 2NaOH + H 2 O 2
2Na 2 O 2 + 2H 2 O (hor.) = 4NaOH + O 2
Na 2 O 2 + 2HCl = 2NaCl + H 2 O 2
2Na 2 O 2 + 2H 2 SO 4 (divided horizon) = 2Na 2 SO 4 + 2H 2 O + O 2
2Na 2 O 2 + S = Na 2 SO 3 + Na 2 O
5Na 2 O 2 + 8H 2 SO 4 + 2KMnO 4 = 5O 2 + 2MnSO 4 + 8H 2 O + 5Na 2 SO 4 + K 2 SO 4
Na 2 O 2 + 2H 2 SO 4 + 2NaI = I 2 + 2Na 2 SO 4 + 2H 2 O
Na 2 O 2 + 2H 2 SO 4 + 2FeSO 4 = Fe 2 (SO 4) 3 + Na 2 SO 4 + 2H 2 O
3Na 2 O 2 + 2Na 3 = 2Na 2 CrO 4 + 8NaOH + 2H 2 O
Bases (alkalis).
2NaOH (excess) + CO 2 = Na 2 CO 3 + H 2 O
NaOH + CO 2 (excess) = NaHCO 3
SO 2 + 2NaOH (excess) = Na 2 SO 3 + H 2 O
SiO 2 + 2NaOH Na 2 SiO 3 + H 2 O
2NaOH + Al 2 O 3 2NaAlO 2 + H 2 O
2NaOH + Al 2 O 3 + 3H 2 O = 2Na
NaOH + Al(OH) 3 = Na
2NaOH + 2Al + 6H 2 O = 2Na + 3H 2
2KOH + 2NO2 + O2 = 2KNO3 + H2O
KOH + KHCO 3 = K 2 CO 3 + H 2 O
2NaOH + Si + H 2 O = Na 2 SiO 3 + H 2
3KOH + P 4 + 3H 2 O = 3KH 2 PO 2 + PH 3
2KOH (cold) + Cl 2 = KClO + KCl + H 2 O
6KOH (hot) + 3Cl 2 = KClO 3 + 5KCl + 3H 2 O
6NaOH + 3S = 2Na2S + Na2SO3 + 3H2O
2NaNO 3 2NaNO 2 + O 2
NaHCO 3 + HNO 3 = NaNO 3 + CO 2 + H 2 O
NaI → Na + + I –
at the cathode: 2H 2 O + 2e → H 2 + 2OH – 1
at the anode: 2I – – 2e → I 2 1
2H 2 O + 2I – 
H 2 + 2OH – + I 2
2H2O + 2NaI 
H 2 + 2NaOH + I 2
2NaCl 
2Na + Cl2
at the cathode at the anode
2Na 2 HPO 4 Na 4 P 2 O 7 + H 2 O
KNO 3 + 4Mg + 6H 2 O = NH 3 + 4Mg(OH) 2 + KOH
4KClO 3 KCl + 3KClO 4
2KClO3 
2KCl + 3O 2
KClO 3 + 6HCl = KCl + 3Cl 2 + 3H 2 O
Na 2 SO 3 + S = Na 2 S 2 O 3
Na 2 S 2 O 3 + H 2 SO 4 = Na 2 SO 4 + S↓ + SO 2 + H 2 O
2NaI + Br 2 = 2NaBr + I 2
2NaBr + Cl 2 = 2NaCl + Br 2
I A group.
1. Electrical discharges were passed over the surface of a caustic soda solution poured into a flask, and the air in the flask turned brown, which disappeared after some time. The resulting solution was carefully evaporated and it was determined that the solid residue was a mixture of two salts. When this mixture is heated, gas is released and the only substance remains. Write the equations for the reactions described.
2. The substance released at the cathode during the electrolysis of molten sodium chloride was burned in oxygen. The resulting product was placed in a gasometer filled with carbon dioxide. The resulting substance was added to the ammonium chloride solution and the solution was heated. Write the equations for the reactions described.
3) Nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was added to a solution of potassium permanganate acidified with sulfuric acid, and the solution became colorless. The nitrogen-containing reaction product was placed in a solution of sodium hydroxide and zinc dust was added, and a gas with a pungent odor was released. Write the equations for the reactions described.
4) The substance obtained at the anode during the electrolysis of a sodium iodide solution with inert electrodes was reacted with potassium. The reaction product was heated with concentrated sulfuric acid, and the liberated gas was passed through a hot solution of potassium chromate. Write the equations for the reactions described
5) The substance obtained at the cathode during the electrolysis of molten sodium chloride was burned in oxygen. The resulting product was successively treated with sulfur dioxide and a solution of barium hydroxide. Write the equations for the reactions described
6) White phosphorus dissolves in a solution of potassium hydroxide, releasing a gas with a garlicky odor, which spontaneously ignites in air. The solid product of the combustion reaction reacted with caustic soda in such a ratio that the resulting white substance contains one hydrogen atom; when the latter substance is calcined, sodium pyrophosphate is formed. Write the equations for the reactions described
7) An unknown metal was burned in oxygen. The reaction product interacts with carbon dioxide to form two substances: a solid that reacts with a solution of hydrochloric acid to release carbon dioxide, and a gaseous simple substance that supports combustion. Write the equations for the reactions described.
8) Brown gas was passed through an excess of caustic potassium solution in the presence of a large excess of air. Magnesium shavings were added to the resulting solution and heated, and the resulting gas neutralized the nitric acid. The resulting solution was carefully evaporated, and the solid reaction product was calcined. Write the equations for the reactions described.
9) During the thermal decomposition of salt A in the presence of manganese dioxide, binary salt B and a gas that supports combustion and is part of the air were formed; When this salt is heated without a catalyst, salt B and a salt of a higher oxygen-containing acid are formed. When salt A interacts with hydrochloric acid, a yellow-green gas (a simple substance) is released and salt B is formed. Salt B turns the flame purple, and when it interacts with a solution of silver nitrate, a white precipitate forms. Write the equations for the reactions described.
10) Copper shavings were added to heated concentrated sulfuric acid and the released gas was passed through a solution of caustic soda (excess). The reaction product was isolated, dissolved in water and heated with sulfur, which dissolved as a result of the reaction. Dilute sulfuric acid was added to the resulting solution. Write the equations for the reactions described.
11) Table salt was treated with concentrated sulfuric acid. The resulting salt was treated with sodium hydroxide. The resulting product was calcined with excess coal. The gas released reacted in the presence of a catalyst with chlorine. Write the equations for the reactions described.
12) Sodium reacted with hydrogen. The reaction product was dissolved in water, which formed a gas that reacted with chlorine, and the resulting solution, when heated, reacted with chlorine to form a mixture of two salts. Write the equations for the reactions described.
13) Sodium was burned in excess oxygen, the resulting crystalline substance was placed in a glass tube and carbon dioxide was passed through it. The gas coming out of the tube was collected and phosphorus was burned in its atmosphere. The resulting substance was neutralized with an excess of sodium hydroxide solution. Write the equations for the reactions described.
14) A solution of hydrochloric acid was added to the solution obtained by reacting sodium peroxide with water when heated until the reaction was completed. The solution of the resulting salt was subjected to electrolysis with inert electrodes. The gas formed as a result of electrolysis at the anode was passed through a suspension of calcium hydroxide. Write the equations for the reactions described.
15) Sulfur dioxide was passed through a solution of sodium hydroxide until a medium salt was formed. An aqueous solution of potassium permanganate was added to the resulting solution. The resulting precipitate was separated and treated with hydrochloric acid. The released gas was passed through a cold solution of potassium hydroxide. Write the equations for the reactions described.
16) A mixture of silicon (IV) oxide and magnesium metal was calcined. The simple substance obtained as a result of the reaction was treated with a concentrated solution of sodium hydroxide. The released gas was passed over heated sodium. The resulting substance was placed in water. Write the equations for the reactions described.
17) The product of the reaction of lithium with nitrogen was treated with water. The resulting gas was passed through a solution of sulfuric acid until the chemical reactions stopped. The resulting solution was treated with a barium chloride solution. The solution was filtered, and the filtrate was mixed with sodium nitrate solution and heated. Write the equations for the reactions described.
18) Sodium was heated in a hydrogen atmosphere. When water was added to the resulting substance, gas evolution and the formation of a clear solution were observed. Brown gas was passed through this solution, which was obtained as a result of the interaction of copper with a concentrated solution of nitric acid. Write the equations for the reactions described.
19) Sodium bicarbonate was calcined. The resulting salt was dissolved in water and mixed with an aluminum solution, resulting in the formation of a precipitate and the release of a colorless gas. The precipitate was treated with an excess of nitric acid solution, and the gas was passed through a solution of potassium silicate. Write the equations for the reactions described.
20) Sodium was fused with sulfur. The resulting compound was treated with hydrochloric acid, the released gas completely reacted with sulfur (IV) oxide. The resulting substance was treated with concentrated nitric acid. Write the equations for the reactions described.
21) Sodium is burned in excess oxygen. The resulting substance was treated with water. The resulting mixture was boiled, after which chlorine was added to the hot solution. Write the equations for the reactions described.
22) Potassium was heated in a nitrogen atmosphere. The resulting substance was treated with an excess of hydrochloric acid, after which a suspension of calcium hydroxide was added to the resulting mixture of salts and heated. The resulting gas was passed through hot copper (II) oxide. Write the equations for the reactions described.
23) Potassium was burned in an atmosphere of chlorine, the resulting salt was treated with an excess of an aqueous solution of silver nitrate. The precipitate that formed was filtered off, the filtrate was evaporated and carefully heated. The resulting salt was treated with an aqueous solution of bromine. Write the equations for the reactions described.
24) Lithium reacted with hydrogen. The reaction product was dissolved in water, which formed a gas that reacted with bromine, and the resulting solution, when heated, reacted with chlorine to form a mixture of two salts. Write the equations for the reactions described.
25) Sodium was burned in air. The resulting solid absorbs carbon dioxide, releasing oxygen and salt. The last salt was dissolved in hydrochloric acid, and a solution of silver nitrate was added to the resulting solution. A white precipitate formed. Write the equations for the reactions described.
26) Oxygen was exposed to an electric discharge in an ozonizer. The resulting gas was passed through an aqueous solution of potassium iodide, and a new gas, colorless and odorless, was released, supporting combustion and respiration. In the atmosphere of the latter gas, sodium was burned, and the resulting solid reacted with carbon dioxide. Write the equations for the reactions described.
I A group.
1. N 2 + O 2 
2NO
2NO + O 2 = 2NO 2
2NO 2 + 2NaOH = NaNO 3 + NaNO 2 + H 2 O
2NaNO 3 2NaNO 2 + O 2
2. 2NaCl 
2Na + Cl2
at the cathode at the anode
2Na + O 2 = Na 2 O 2
2Na 2 O 2 + 2CO 2 = 2Na 2 CO 3 + O 2
Na 2 CO 3 + 2NH 4 Cl = 2NaCl + CO 2 + 2NH 3 + H 2 O
3. NaHCO 3 + HNO 3 = NaNO 3 + CO 2 + H 2 O
2NaNO 3 2NaNO 2 + O 2
5NaNO 2 + 2KMnO 4 + 3H 2 SO 4 = 5NaNO 3 + 2MnSO 4 + K 2 SO 4 + 3H 2 O
NaNO 3 + 4Zn + 7NaOH + 6H 2 O = 4Na 2 + NH 3
4. 2H2O + 2NaI 
H 2 + 2NaOH + I 2
2K + I 2 = 2KI
8KI + 5H 2 SO 4 (conc.) = 4K 2 SO 4 + H 2 S + 4I 2 + 4H 2 O
3H 2 S + 2K 2 CrO 4 + 2H 2 O = 2Cr(OH) 3 ↓ + 3S↓ + 4KOH
5. 2NaCl 
2Na + Cl2
at the cathode at the anode
2Na + O 2 = Na 2 O 2
Na 2 O 2 + SO 2 = Na 2 SO 4
Na 2 SO 4 + Ba(OH) 2 = BaSO 4 ↓ + 2NaOH
6. P 4 + 3KOH + 3H 2 O = 3KH 2 PO 2 + PH 3
2PH 3 + 4O 2 = P 2 O 5 + 3H 2 O
P 2 O 5 + 4NaOH = 2Na 2 HPO 4 + H 2 O
Zn ZnS H 2 S S SO 2 SO 3 H 2 SO 4 SO 2 S
FeS SO 2 Na 2 SO 3 SO 2 S H 2 S FeS H 2 S SO 2 Na 2 SO 3 Na 2 S 2 O 3
Cu CuSO 4 CuS SO 2 Na 2 SO 3 NaHSO 3 SO 2 SO 3 H 2 SO 4 S Na 2 SO 3
H 2 SO 4 SO 2 S H 2 S PbS SO 2 NaHSO 3 Na 2 SO 3 Na 2 SO 4 BaSO 4
Na 2 S H 2 S SO 2 H 2 SO 3
HCl + O 2 + X + KOH + HCl + KOH
FeS X Y Z F Y F
6. S -2 S 0 S +4 S +6 S +4 S 0 S –2 S +4
Assignments for GIA grade 9:
Colorless gas A, which has a characteristic pungent odor, reacts with another colorless gas, B, which has the smell of rotten eggs. As a result of the reaction, a simple substance C and a complex substance G are formed. C reacts with copper to form a black salt. Decipher substances A, B, D, C.
A simple unstable gaseous substance A transforms into another simple substance B, in the atmosphere of which metal C burns, the product of this reaction is an oxide in which the metal is in two oxidation states. Decipher substances A, B, C. Write the reaction equations.
In the reaction of combining two liquid oxides A and B under normal conditions, substance C is formed, a concentrated solution of which is a colorless oily liquid that chars sucrose and cellulose. Decipher substances A, B, C.
When two substances interact, gas A is formed with the smell of rotten eggs; when it burns in excess oxygen, gas B is formed with an irritating odor. As a result of the interaction of gases A and B, a yellow substance precipitates, when heated with iron, a compound is obtained that reacts with hydrochloric acid to form gas A. Decipher the substances, write the equations for all reactions.
When liquid A and solid substance B interact, gas C and liquid D are formed. Gas C can be oxidized into substance E, which reacts with liquid D to form liquid A. Decipher the substances, write the equations for all reactions.
In one laboratory, the label on one of the bottles was lost. This bottle contained an oily, transparent liquid. To establish the composition of the liquid, the laboratory assistant prepared a solution: he carefully added a small amount of the test liquid to the water in small portions. Significant heating of the solution occurred. The laboratory technician took a sample of the resulting solution and added a few drops of barium nitrate solution, resulting in the formation of a white crystalline precipitate.
– Chemistry: GIA 2012: Test training materials for grade 9 with answers and comments. / A.N. Levkin, S.E. Dombrovskaya. – M.; St. Petersburg: Education.2012
Sulfur and its compounds. Tasks C-2 for the Unified State Exam.
Chemical A is a nonmetal that is widely distributed in nature. Significant deposits of it in a native state are found in Europe, America, and also in Japan. Occurs in the form of allotropic modifications. In nature, it forms compounds with metals, which are widely used in metallurgy. When substance A is burned, gas B is formed with a rather pungent odor, which when dissolved in water forms an acid. When substance A fuses with iron, substance C is formed, which dissolves in sulfuric acid, releasing gas D with the characteristic smell of rotten eggs. Name the substances and write the equations for these reactions.
When a simple yellow substance is burned in air, a gas with a pungent odor is formed. This gas is also released when some mineral containing iron is roasted in air. When dilute sulfuric acid acts on a substance consisting of the same elements as the mineral, but in a different ratio, a gas is released with the characteristic smell of rotten eggs. When the released gases interact with each other, the original simple substance is formed. Write the equations for the reactions described.
The gaseous product of the interaction of dry table salt with concentrated sulfuric acid was reacted with a solution of potassium permanganate. The released gas was passed through a solution of sodium sulfide. The resulting yellow precipitate dissolves in a concentrated solution of sodium hydroxide. Write the equations for the reactions described.
Copper wire was added to heated concentrated sulfuric acid and the released gas was passed through an excess of caustic soda solution. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. The unreacted sulfur was separated by filtration and sulfuric acid was added to the solution, and the formation of a precipitate and the release of a gas with a pungent odor were observed. Write the equations for the reactions described.
A mixture of iron powder and a solid product obtained by the interaction of sulfur dioxide and hydrogen sulfide was heated without access to air. The resulting product was fired in air. The resulting solid reacts with aluminum, releasing large amounts of heat. Write the equations for the reactions described.
Sulfur dioxide was passed through a solution of hydrogen peroxide. Water was evaporated from the resulting solution. And magnesium shavings were added to the remainder. The released gas was passed through a solution of copper sulfate. The resulting black precipitate was separated and fired. Write the equations for the reactions described.
The solid substance formed by the interaction of sulfur dioxide and hydrogen sulfide interacts with aluminum when heated. The reaction product was dissolved in dilute sulfuric acid and potash was added to the resulting solution. Write the equations for the reactions described.
Ferrous sulfide was treated with a solution of hydrochloric acid, the resulting gas was collected and burned in air. The reaction products were passed through an excess of potassium hydroxide solution, after which a solution of potassium permanganate was added to the resulting solution. Write the equations for the reactions described.
Sulfur dioxide was dissolved in water, the solution was neutralized, and sodium hydroxide was added. Hydrogen peroxide was added to the resulting solution and, after the reaction was completed, sulfuric acid was added. Write the equations for the reactions described.
When a certain mineral A, consisting of two elements, is fired, a gas is formed that has a characteristic pungent odor and discolors bromine water with the formation of two strong acids in solution. When substance B, consisting of the same elements as mineral A, but in a different ratio, interacts with concentrated hydrochloric acid, a poisonous gas with the smell of rotten eggs is released. When the released gases interact with each other, a simple yellow substance and water are formed. Write the equations for the reactions described.
G. 03/23/16
Ethylene glycol cannot be obtained from the process
1) oxidation of ethylene with potassium permanganate 2) hydrolysis of dihalogen derivatives of ethane
3) ethylene hydration 4) ethylene oxide hydration
Interaction
Alcohol + Cu(OH) 2 === …… + water
cannot occur with the participation
1) ethanol 2) glucose 3) glycerin 4) ethylene glycol
Formic acid reacts:
1) substitution with sodium 2) neutralization with alkali 3) “silver mirror” 4) esterification with alcohol
Acetic acid can be produced using the reaction:
HgSO 4
1) C 2 H 4 + H 2 O ===
H 3 P.O. 4
2) C 2 H 4 + H 2 O ===
LiAlH 4, C 2 H 5 OH
3) CH 3 COH + H 0 ==========
4) Na(CH 3 COO) + H 2 SO 4 ==
From ethanol in one stage you can get:
1) butane 2) formaldehyde 3) butadiene 1.3 4) butene-2
Potassium can be obtained by electrolysis on carbon electrodes:
1) KCl solution 2) KNO 3 solution 3) KCl melt 4) melt mixture of KCl and MgCl 2
For the synthesis of ammonia, nitrogen obtained in industry is used:
1) the action of water on calcium hydride 2) fractional distillation of liquid air
3) from a mixture of water vapor and hot coke 4) by boiling hydrochloric acid with zinc
In the production of sulfur trioxide from an initial mixture of 4 m 3 SO 2 and 4 m 3 O 2, after complete consumption of one of the gases, the volume will decrease to:
1) 4 2) 5 3) 6 4) 7
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Potassium chromate can be converted to potassium dichromate by adding to the solution:
potassium hydroxide 2) hydrochloric acid 3) copper hydroxide 4) silicic acid
A) CH 3 COCH 3 1) HNO 3
B) CH 2 OH (CHOH) 4 CHO 2) KMnO 4
B) protein 3) FeCl 3
D) CH 2 ONSNONNOSNH 2 OH 4) I 2 (alcohol)
5) Br 2 (water)
Establish a correspondence between the substance and their qualitative reaction:
A) C 2 H 2 1) HNO 3
B) (-C 6 H 10 O 5 -) n 2) FeCl 3
B) C 6 H 5 OH 3) I 2 (alcohol)
D) (CH 3 COO) 2 Ca 4) C 2 H 5 OH (alcohol)
5) Br 2 (water)
6) Ag(NH 3) 2 NO 3
23. Establish a correspondence between the substances and the reagent, with the help of which they can be distinguished from each other:
A) K 2 CO 3 and K 3 PO 4 1) KCNS
B) Zn(NO 3) 2 and Ba (NO 3) 2 2) SiO 2
B) FeCl 2 and FeCl 3 3) Cu(OH) 2
D) NaH and NaCl 2 4) H 2 O
24.
A) CaC 2 1) H 2 O, Ba(OH) 2, Mg
B) CaCO 3 2) H 2, H 2 O, NaCl
B) HPO 3 3) O 2, Cl, KOH
D) Si 4) CO, KCl, NaOH
5) HCl, H2O, H2
6) CO 2, HNO 3, SiO 2
25. Acetaldehyde
1) reacts with methanol
2) dissolves in water
3) reduced by hydrogen
4) does not react with the “silver mirror”
5) reacts with phenol
6) reacts with chlorine in the light
23. Establish a correspondence between the substances and the reagent, with the help of which they can be distinguished from each other:
A) Ca(NO 3) 2 and NaNO 3 1) KI
B) Be(NO 3) 2 and Cu(NO 3) 2 2) BaCO 3
B) AgNO 3 and AgCl 3) NaOH
D) Na 2 SiO 3 and Na 2 SO 4 4) HCl
24. Match the name of the substance with the list of substances with each of which it can react
A) Al 1) O 2, HNO 3 (p - p), Na
B) S 2) Cl 2, HBr, NaOH
B) CO 3) HF, C, KOH
D) Ba 4) CO, KCl, NaOH
5) P 4 , H 2 O, C
6) O 2, Cr 2 O 3, NaOH
25. Glycerol
1) reacts with nitric acid
2) dissolves in water
3) reacts with Cu(OH) 2
4) reacts with carboxylic acids
5) undergoes alcoholic fermentation
6) does not undergo combustion and oxidation
The decomposition products of ammonium chloride were passed through a heated tube containing copper (II) oxide and then through a flask with phosphorus (V) oxide. Write down equations for the four reactions described.
. The gaseous product of the interaction of dry table salt with concentrated sulfuric acid was reacted with a solution of potassium permanganate. The released gas was passed through a solution of sodium sulfide. The yellow precipitate that formed dissolved in a concentrated solution of sodium hydroxide. Write down equations for the four reactions described.
The solution of ferric chloride was treated with a solution of sodium hydroxide, the precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Sodium nitrate and hydroxide were added to the remaining substance and heated at high temperature for a long time. Write down equations for the four reactions described.
. A solution of ferric chloride (III) was subjected to electrolysis with graphite electrodes. The resulting brown precipitate (a by-product of electrolysis) was filtered, calcined and fused with the substance formed at the cathode. Another substance, also released at the cathode, was introduced into a reaction with the product released during electrolysis at the anode; the reaction occurs under illumination and with an explosion. Write down equations for the four reactions described.
H 2 , (cat)Na HCl KMnO 4 , H 2 SO 4
CH 4 ===== HCHO===== X 1 ======= X 2 ========= X 1 =========== = X 3
Br 2 KOH,H 2 O K 2 Cr 2 O 7 , H 2 SO 4 , H 2 Ot 0 , cat.
C 2 H 6 ===== X 1 ===== X 2 ================ CH 3 CHO ========= X 2 ============ divinyl
Na Pb, the CH 3 C.L., AlCl 3 KMnO 4 , KOH
CH 3 CH 2 CH 2 Br =====X 1 ===== X 2 ======= X 3 ========= ======= ===== X 2
HBr KOH(alcohol) catBr 2 , lightKOH(alcohol)
CH 3 CH 2 OH =====X 1 ========= X 2 ======= C 6 H 5 C 2 H 5 ========= X 3 ============ X 4
A mixture of magnesium and magnesium carbonate was treated with hydrochloric acid. 22.4 liters (n.s.) of gas were collected, after combustion of which in air and subsequent drying, its volume became 8.96 liters (n.s.). Find the mass fraction (in%) of the metal in the original mixture.
The gas released when calcium hydride was treated with water was passed over hot iron (III) oxide. The oxide reacted completely, the solid residue became 32 g lighter than the oxide; In this case, half of the gas volume was used. Set the mass (in grams) of the hydride taken.
When 16.18 ml of monohydric alcohol (density equal to 0.791 g/ml) interacted with sodium, a gas was released, which was spent on converting 4.48 liters (n.s.) of ethylene into the corresponding alkane. Derive the formula of the alcohol taken.
Determine the molecular formula of an organic substance if its combustion with a mass of 2.16 g produces 0.72 g of water and 1.568 liters of carbon dioxide. Draw the structural formula of an organic compound if, when it is chlorinated in the light, only one monochloro-substituted compound is formed, and when it reacts with bromine water, two different monobromo-substituted compounds can be formed.
From the rehearsal test options (V.N. Doronkin “Preparation for the Unified State Exam – 2012”)
1. The solution obtained by reacting copper with concentrated nitric acid was evaporated and the precipitate was calcined. The gaseous products of the decomposition reaction are completely absorbed by water, and hydrogen is passed over the solid residue. Write the equations for the reactions described.
C getting the answer
1) Cu+4HNO 3(conc) →Cu(NO 3) 2 +2NO 2 +2H 2 O
2) 2 Cu(NO 3) 2 → 2CuO +4NO 2 +O 2
3) CuO + H 2 → Cu + H 2 O
4) 4NO 2 +2H 2 O+O 2 →4HNO 3
2. A simple substance obtained by heating calcium phosphate with coke and silicon oxide was fused with calcium metal. The reaction product was treated with water, and the released gas was collected and passed through a solution of hydrochloric acid. Write the equations for the reactions described.
C getting the answer
1) Ca 3 (PO 4) 2 ↓+5C+3SiO 2 → 3CaSiO 3 +2P+ 5CO
2) 2Р+3Са→Са 3 Р 2
3) Ca 3 P 2 +6H 2 O → 3Ca(OH) 2 +2PH 3
4) RN 3 +HC1→RN 4 C1
3) The solution of ferric chloride was treated with a solution of sodium hydroxide. The precipitate that formed was separated and heated. The solid reaction product was mixed with soda ash and calcined. Sodium nitrate and hydroxide were added to the remaining substance and heated at high temperature for a long time.
Write the equations for the reactions described.
C getting the answer
1) FeС1 3 +3NаОН→Fe(ОН) 3 ↓+3NаС1
2) 2Fe(OH) 3 → Fe 2 O 3 ↓+3H 2 O
3) Fe 2 O 3 + Na 2 CO 3 → 2NaFeO 2 + CO 2
4) 2NaFeO 2 +3NaNO 3 +2NaOH → 2Na 2 FeO 4 +2NaNO 2 + H 2 O
4) Concentrated hydrochloric acid was added to lead(IV) oxide while heating. The released gas was passed through a heated solution of caustic potassium. The salt of the oxygen-containing acid, which precipitated when the solution was cooled, was filtered and dried. When the resulting salt is heated with hydrochloric acid, a poisonous gas is released, and when it is heated in the presence of manganese dioxide, a gas that is part of the atmosphere is released. Write the equations for the reactions described.
C getting the answer
1) 4НCl + РbО 2 → РbС1 2 ↓ +2Н 2 О+ Cl 2
2) 6KOH+ 3Cl 2 →5KS1+KS1O 3 +3H 2 O
3) KS1O 3 +6HC1→KS1+3C1 2 +3H 2 O
4) 2KS1O 3 →2KS1+3O 2
5) Excess sodium hydroxide solution was added to the aluminum sulfate solution. Hydrochloric acid was added to the resulting solution in small portions, and the formation of a voluminous white precipitate was observed, which dissolved with further addition of acid. A solution of sodium carbonate was added to the resulting solution. Write the equations for the written reactions.
1) A1 2 (SO 4) 3 + 8NaOH→2Na+3Na 2 SO 4 or A1 2 (SO 4) 3 + 12NaOH→2Na 3 +3Na 2 SO 4
2) Na 3 +3HC1→3NaС1+Al(OH) 3 ↓+3H2O
3) Al(OH) 3 ↓+3HC1 → A1C1 3 +3H 2 O
4) 2AlС1 3 +3H 2 O+3Na 2 CO 3 →3СО 2 +2А1(ОН) 3 ↓+6NaС1
6) After briefly heating an unknown orange powdery substance, a spontaneous reaction begins, which is accompanied by a change in color to green, the release of gas and sparks. The solid residue was mixed with potassium hydroxide and heated, the resulting substance was added to a dilute solution of hydrochloric acid, and a green precipitate was formed, which dissolves in excess acid. Write the equations for the reactions described.
1)(NH 4) 2 Cr 2 O 7 →Cr 2 O 3 +N 2 +4H 2 O
2) Cr 2 O 3 + 4KOH→2KCrO 2 +H 2 O
3)KCrO 2 + HCl+H 2 O→Cr(OH) 3↓ +KCl
4) Cr(OH) 3 +3HCl (excess) →CrCl 3 +3H 2 O
7) Nitric acid was neutralized with baking soda, the neutral solution was carefully evaporated and the residue was calcined. The resulting substance was added to a solution of potassium permanganate acidified with sulfuric acid. the solution became discolored. The nitrogen-containing reaction product was placed in a solution of caustic soda and zinc dust was added, and a gas with a sharp characteristic odor was released. Write the equations for the reactions described.
1) NaHCO 3 +HNO 3 →NaNO 3 +CO 2 +H 2 O
2) 2 NaNO 3 →2NaNO 2 +O 2
3) 5 NaNO 2 +2KMnO 4 +3H 2 SO 4 →5NaNO 3 + K 2 SO 4 +Mn 2 SO 4 +3H 2 O
4) NaNO 3 +4Zn+7NaOH+6H 2 O→NH 3 +4Na 2
8) The substance obtained at the cathode during the electrolysis of molten sodium chloride was burned in oxygen. The resulting product was successively treated with sulfur dioxide and a barium hydroxide solution. Write the equations for the reactions described.
1) 2NaCl→2Na+Cl 2
2) 2Na+O 2 →Na 2 O 2
3) Na 2 O 2 +SO 2 →Na 2 SO 4
4) Na 2 SO 4 +Ba(OH) 2 → BaSO 4 ↓+2NaOH
9) Quicklime was calcined with excess coke. The reaction product after treatment with water is used to absorb sulfur dioxide and carbon dioxide. Write the equations for the reactions described
1) CaO + 3C → CaC 2 + CO
2) CaC 2 +2H 2 O→Ca(OH) 2 ↓+C 2 H 2
3) Ca(OH) 2 +CO 2 →CaCO 3 ↓+H 2 O or Ca(OH) 2 +2CO 2 →Ca(HCO 3) 2
4) Ca(OH) 2 +SO 2 →CaSO 3 ↓+H 2 O or Ca(OH) 2 +2SO 2 →Ca(HSO 3) 2
10) Copper wire was added to heated concentrated sulfuric acid and the resulting gas was passed through an excess of caustic soda. The solution was carefully evaporated, the solid residue was dissolved in water and heated with powdered sulfur. The unreacted sulfur was separated by filtration and sulfuric acid was added to the solution, and the formation of a precipitate and the release of a gas with a pungent odor were observed.
Write the equations for the reactions described
1) Cu+ 2H 2 SO 4 →CuSO 4 +SO 2 +2H 2 O
2) 2NaOH+ SO 2 →Na 2 SO 3 +H 2 O
3) Na 2 SO 3 +S→ Na 2 S 2 O 3
4) Na 2 S 2 O 3 + H 2 SO 4 → Na 2 SO 4 +SO 2 +S↓+H 2 O
11) The substance formed by the fusion of magnesium with silicon was treated with water, resulting in the formation of a precipitate and the release of a colorless gas. The precipitate was dissolved in hydrochloric acid, and the gas was passed through a solution of potassium permanganate. in this case, two water-insoluble binary compounds were formed. Write the equations for the reactions described
1) Si + 2Mg = Mg 2 Si
2) Mg 2 Si + 4H 2 O = 2Mg(OH) 2 + SiH 4
3) Mg(OH) 2 +2HCl→MgCl2 +2H2O
4) 3SiH 4 + 8KMnO 4 →8MnO 2 ↓+ 3SiO 2 ↓ +8KOH+ 2H 2 O
12 ) A solution of hydrochloric acid was added to a white, water-insoluble salt that occurs in nature as a mineral widely used in construction and architecture. As a result, the salt dissolved and a gas was released, which, when passed through lime water, formed a white precipitate, which dissolved when the gas was further passed through. When the resulting solution is boiled, a precipitate forms and gas is released. Write the equations for the reactions described.
1) CaCO 3 +2HC1 →CaC1 2 +CO 2 +H 2 O
2) Ca(OH) 2 +CO 2 →CaCO 3 ↓+H 2 O
3) CaCO 3 ↓+H 2 O +CO 2 →Ca(HCO 3) 2
4) Ca(HCO 3) 2 →CaCO 3 ↓+H 2 O+CO 2
13) The salt obtained by reacting zinc oxide with sulfuric acid was calcined at 800 0 C. The solid reaction product was treated with a concentrated alkali solution and carbon dioxide was passed through the resulting solution. Write the equations for the reactions described.
1) ZnO+H 2 SO 4 →ZnSO 4 +H 2 O
2) 2 ZnSO 4 →ZnO+2SO 2 +O 2
3) ZnO+2NaOH+H3O→Na 2
4) Na 2 +2CO 2 → 2NaHCO 3 +Zn(OH) 2 ↓ or Na 2 +CO 2 → Na 2 CO 3 +Zn(OH) 2 ↓ +H 2 O
14) Soda ash was added to the solution of trivalent chromium sulfate. The precipitate that formed was separated, transferred to a solution of sodium hydroxide, bromine was added and heated. After neutralizing the reaction products with sulfuric acid, the solution acquires an orange color, which changes to green after passing sulfur dioxide through the solution. Write the equations for the reactions described
1) Cr 2 (SO 4) 3 +3Na 2 CO 3 +3H 2 O →2Cr(OH) 3 ↓ + 3Na 2 SO 4 +3CO 2
2) 2Cr(OH) 3 + 10NaOH+3Br 2 →2Na 2 CrO 4 + 6NaBr+8H 2 O
3) 2Na 2 CrO+H 2 SO 4 →Na 2 Cr 2 O 7 +Na 2 SO 4 +H 2 O
4) Na 2 Cr 2 O 7 +3SO 2 +H 2 SO 4 →Na 2 SO 4 +Cr 2 (SO 4) 3 +H 2 O
15) Phosphine was passed through a hot solution of concentrated nitric acid. The reaction products were neutralized with quicklime, the precipitate that formed was separated, mixed with coke and silica and calcined. The reaction product, which glows in the dark, was heated in a solution of sodium hydroxide. Write the equations for the reactions described
1) PH 3 + 8HNO 3(clnts) → H 3 PO 4 + 8NO 2 +4H 2 O
2)2H 3 PO 4 +3CaO→Ca 3 (PO 4) 2 ↓+3H 2 O and 2HNO 3 +CaO→Ca(NO 3) 2 +H 2 O
3) Ca 3 (PO 4) 2 ↓+5C+3SiO 2 → 3CaSiO 3 +2P+ 5CO
4) P 4 +3 NaOH + 3H 2 O → 3NaH 2 PO 2 + PH 3
16) The black powder, which was formed when the red metal was burned in excess air, was dissolved in 10% sulfuric acid. Alkali was added to the resulting solution and the blue precipitate that formed was separated and dissolved in an excess of ammonia solution. Write the equations for the reactions described.
1) 2Cu+O 3 →2CuO
2) CuO +H 2 SO 4 →CuSO 4 +H 2 O
3) CuSO 4 +2NaOH →Cu(OH) 2 ↓+Na 2 SO 4
4) Cu(OH) 2 ↓+4NH 3 ∙H 2 O→(OH) 2 +4H 2 O
17) Red phosphorus was burned in a chlorine atmosphere. The reaction product was treated with excess water and powdered zinc was added to the solution. The released gas was passed over a heated plate of oxidized copper. Write the equations for the reactions described
1)2P+5Cl 2 →2PCl 5
2) PCl 5 +4H 2 O→ H 3 PO 4 +5HCl
3) 3Zn+2H 3 PO 4 →Zn 3 (PO 4) 2 ↓+3H 2 and Zn + 2HCl →ZnCl 2 +H 2
4) CuO+H 2 →Cu+H 2 O
18) The substance obtained at the anode by electrolysis of a sodium iodine solution on inert electrodes was reacted with potassium. The reaction product was heated with concentrated sulfuric acid and the liberated gas was passed through a hot solution of potassium chromate. Write the equations for the reactions described
1) 2КI +2H 2 O→2КOH+ I 2 ↓
2) I 2 +2K→ 2KI
3) 8KI+5H 2 SO 4 →4 I 2 ↓+H 2 S+4K 2 SO 4 +4H 2 O or 8KI+9H 2 SO 4 →4 I 2 ↓+H 2 S+8KHSO 4 +4H 2 O
4)3H 2 S+ 2K 2 CrO 4 +2H 2 O→2Cr(OH) 3 ↓+3S↓+4KOH
19) The gas formed as a result of the reaction of hydrogen chloride with a hot solution of potassium chromate reacts with iron. The reaction product was dissolved in water and sodium sulfide was added to it. The lighter substance from the resulting insoluble compounds was separated and reacted with concentrated sulfuric acid while heating. Write the equations for the reactions described.
1) 2K 2 CrO 4 +16HCl →4КCl+2CrCl 7 +3Cl 2 +H 2 O
2) 2Fe+3Cl 2 →2FeCl 3
3) 2FeCl 3 +3Na 2 S→S↓+FeS↓+6NaCl
4) S +2H 2 SO 4 →2SO 2 +2H 2 O
20) Two salts turn the flame purple. One of them is colorless, and when it is slightly heated with concentrated sulfuric acid, the liquid in which copper dissolves is distilled off; the latter transformation is accompanied by the release of brown gas. When a second salt of a sulfuric acid solution is added to the solution, the yellow color of the solution changes to orange, and when the resulting solution is neutralized with alkali, the original color is restored. Write the equations for the reactions described
1) KNO 3 +2H 2 SO 4 →KHSO 4 +HNO 3
2) Cu+4HNO 3(conc) →Cu(NO 3) 2 +2NO 2 +2H 2 O
3) 2K 2 CrO 4 +H 2 SO 4 →K 2 Cr 2 O 7 +K 2 SO 4 +H 2 O
4) K 2 Cr 2 O 7 +2KOH→2K 2 CrO 4 +H 2 O