Study of Compounds — Hydrogen Chloride — Question 4

(a) When Sodium carbonate is treated with dil. HCl, odourless carbon dioxide gas is produced.

Na₂CO₃ + 2HCl ⟶ 2NaCl + H₂O + CO₂ ↑

However, when sodium sulphite is treated with dil.HCl, sulphur dioxide gas with a suffocating odour (burning smell) is produced.

Na₂SO₃ + 2HCl ⟶ 2NaCl + H₂O + SO₂ ↑

(b) When sodium thiosulphate is treated with dil. HCl it produces sulphur dioxide gas and yellow sulphur precipitates.

Na₂S₂O₃ + 2HCl ⟶ 2NaCl + S + H₂O + SO₂ ↑

However, S is not produced when sodium sulphite is treated with dil.HCl.

Na₂SO₃ + 2HCl ⟶ 2NaCl + H₂O + SO₂ ↑