Question

How will the action of dilute hydrochloric acid enable you to distinguish between the following:

(a) Sodium carbonate and sodium sulphite

(b) sodium thiosulphate and sodium sulphite

Answer 1

(a). Sodium carbonate on treating with dil. HCl results in the formation of sodium chloride with the liberation of carbon dioxide gas.

Sodium sulphite on treating with dil. HCl results in the formation of sodium chloride with the liberation of sulphur dioxide gas.

(b). Sodium thiosulphate reacts with dil. HCl to produce sulphur dioxide gas and precipitates yellow sulphur.

Sulphur is not precipitated when sulphites are treated with dil. HCl.