Question

Why does dry HCL gas not change the colour of the dry litmus paper?​

Answer 1

Answer:

Acidic properties are shown only in form of H+/H3O+ ions.

Explanation:

Dry HCl does not dissociate into acidic or basic ions. For a substance to show it's acidic properties on litmus paper, water should be present so that the substance could accordingly form H+/H3O+ ions or OH- ions according to its acidity or basicity respectively. Thus for dry HCl to show colour change on litmus paper, the paper should be wet with water, or HCl dissolved in small amount of water should be used in dry litmus paper.

Answer 2

Explanation:

To change the colour of litmus paper H+ ions are required but they are not presented in dry HCL but only present in hydrated solution of HCL. so litmus paper doesn't change its colour by dry HCL( hydrated ions are absent).