Question

Give reason for the following fact:

Sulphur disappears when boiled with an aqueous solution of sodium sulphite.

Answer 1

1. Sodium sulphite solution contains sulphite ions \[\ce{(SO^{2-}_3)}\].
2. Sulphur reacts with these sulphite ions.
3. A chemical reaction takes place forming thiosulphate ions \[\ce{(S2O^{2-}_3)}\].
4. Sulphur gets consumed in the reaction and hence disappears.
5. Reaction: \[\ce{S + SO^{2-}_3 -> S2O^{2-}_3}\]

Thus, sulphur dissolves due to conversion into thiosulphate ion on boiling with sodium sulphite solution.