Question

Explain why dry hydrogen chloride gas does not affect a dry strip of blue litmus paper but it turns red in the presence of a drop of water.

Answer 1

A dry strip of blue litmus paper is unaffected by dry HCl gas due to the gas’s non-acidic nature. In the presence of a drop of water, HCl gas dissolves and produces hydrochloric acid, which turns blue litmus paper red.