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ICSE Class 10 Chemistry Question 22 of 23

Model Paper 2 — Question 22

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22
Question

Question 8(iii)

Distinguish between the following as directed:

(a) Sodium Sulphite and Sodium Sulphate by using dilute HCl.

(b) Ammonium chloride and Sodium chloride by using Calcium hydroxide.

(c) Lead nitrate and silver nitrate by using HCl.

Answer

(a) When Sodium sulphite reacts with HCl, effervescence occurs and a pungent gas (SO2) is evolved that turns acidified potassium dichromate paper from orange to green.

Na2SO3 + 2HCl ⟶ 2NaCl + H2O + SO2 ↑

Whereas, Sodium sulphate (Na2SO4) gives no visible reaction with HCl and no gas is evolved.

(b) Ammonium Chloride (NH4Cl) reacts with Ca(OH)2 to release ammonia gas (NH3) which has pungent smell, turns red litmus blue.

2NH4Cl + Ca(OH)2 ⟶ CaCl2 + 2H2O + 2NH3↑

Whereas, sodium chloride shows no reaction with Calcium hydroxide.

(c) Lead Nitrate (Pb(NO3)2) reacts with HCl, forms a white precipitate of lead chloride (PbCl2) which is soluble in hot water.

Pb(NO3)2 + 2HCl ⟶ PbCl2 ↓ + 2HNO3

However, when Silver nitrate reacts with HCl, it forms a white precipitate of silver chloride (AgCl) which is insoluble in hot water

AgNO3 + HCl ⟶ AgCl ↓ + HNO3