ICSE CHEMISTRY CLASS 10 - AMMONIA - SEMESTER 2

ICSE CHEMISTRY STUDY OF COMPOUNDS IMPORTANT QUESTIONS AND SOLUTIONS 

Name the following.

1. The gas released when Ammonium chloride is warmed with Sodium hydroxide.

Ans: Ammonia gas

2. The negative ions produced when Ammonia gas dissolves in water.

Ans: Hydroxyl ion

3. The gas which burns with greenish yellow flame.

Ans: Dry Ammonia gas

4. The process in which Ammonia is prepared in large quantity.

Ans: Haber’s process

5. The substance used for drying Ammonia gas.

Ans: Calcium oxide (Quick lime)

6. The gas produced when Ammonia is oxidized in presence of Platinum.

Ans: Nitric oxide on further oxidation gives Nitrogen dioxide gas

7. The gas produced when excess Ammonia reacts with Chlorine.

Ans: Nitrogen trichloride

8. The alkaline gas which reduces CuO to Cu.

Ans: Ammonia gas

9. The ammonium compound which on thermal decomposition gives Nitrogen gas.

Ans: Ammonium nitrite

 

10. The gas which turns moist litmus paper to blue.

Ans: Ammonia gas

Observations seen when:

1. Fountain experiment using Ammonia gas.

Ans: A blue fountain ejects from the jet tube inside the Round Bottom Flask

2. Oxidation of Ammonia in the absence of catalyst.

Ans: Greenish yellow flame

 

3. Cu²⁺ salt is treated with Ammonium hydroxide in small amounts then in excess amount.

Ans: Pale blue precipitate which turns inky blue solution with excess Ammonium hydroxide

4. Excess Ammonia with Chlorine gas.

Ans: Dense white fumes

5. CuO is heated with Ammonia gas.

Ans: Pinkish brown residue

6. Calcium hydroxide is heated with Ammonium chloride.

Ans: A colourless gas with pungent odour which gives dense white fumes with a glass rod dipped in conc. HCl

 

Give reasons:

1. In the laboratory preparation of Ammonia, Calcium hydroxide is taken in excess quantity.

Ans: To counteract the sublimation of Ammonium chloride

2. Ammonium nitrate is not used in the preparation of Ammonia gas.

Ans: Ammonium nitrate on heating decomposes to give Nitrous oxide instead of Ammonia gas and nitrate salts are explosive as well.

3. Conc. H₂SO₄ is not used as a drying agent for Ammonia gas.

Ans: Conc. Sulphuric acid reacts with basic Ammonia gas and forms Ammonium sulphate salt which causes loss of Ammonia gas.

4. Round bottom flask is kept in inclined position in the preparation of Ammonia in laboratory preparation of Ammonia.

Ans: To prevent water trickle down the Round Bottom Flask and reach the hotter part of it which causes cracks.

 

5. NaOH is not preferred in the laboratory preparation of Ammonia gas.

Ans: Sodium hydroxide is deliquescent in nature and absorbs moisture from atmosphere and dissolves in it.

6. In Haber’s process the reaction mixture is heated initially only.

Ans: The reaction involved in Haber’s process is an exothermic reaction and the heat evolved will be sufficient for the further reaction to take place. Hence external heating is not required

7. Lead hydroxide is insoluble in excess Ammonium hydroxide but Copper hydroxide is soluble.

Ans: Copper hydroxide in excess Ammonium hydroxide forms a soluble complex compound but Lead hydroxide does not.

 

8. Ammonia gas is not collected over water.

Ans: Ammonia gas is highly soluble in water

9. Platinum continues to glow even after the heating is discontinued in catalytic oxidation of Ammonia gas.

Ans: Catalytic oxidation of Ammonia gas is an exothermic reaction hence the heat evolved in the reaction keeps it hot and glowing.