ICSE CHEMISTRY CLASS 10 - Answers - Give reasons - HCl

ICSE CHEMISTRY CLASS 10 Give reasons - Hydrogen chloride

1.     HCl gas is not collected over water.

Ans: HCl is highly soluble in water.

2.     In the laboratory preparation of HCl, temperature is maintained below 200⁰C.

Ans: - To save fuel. If temperature is above 200⁰C, a hard crust of Sodium sulphate is formed in the round bottom flask.

3.     HCl gas exposed to Ammonia gives white dense fumes.

Ans: HCl  combines with Ammonia to form Ammonium chloride fumes.

4.     Conc. HNO₃ is not used instead of Conc. Sulphuric acid in the preparation of HCl gas.

Ans: Conc HNO₃ being a volatile acid, it cannot displace another volatile acid i.e. HCl from NaCl.

5.     Hydrochloric acid is not prepared by dissolving HCl gas directly in water.

Ans: Direct dissolution of HCl in water causes back-suction which may cause breakage to the apparatus.

6.     HCl gas cannot be dried using quick lime.

Ans: HCl reacts with basic Calcium oxide (Quick lime) and gives Calcium chloride.

7.     HCl in water conducts electricity but in Toluene does not.

Ans: HCl  gets ionized in water but in Toluene does not.

8.     HCl gas fumes in moist air but H₂S does not.

Ans: HCl is highly soluble in water hence it forms mist with atmospheric moisture, where as H₂S is slightly soluble in water.

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