Question

“Dry HCl gas does not change the colour of dry blue litmus paper”. Give reasons

Answer 1

Hi,

Dry HCl does not contain H⁺ in the dissociated form while the aqueous solution does contain it.

For the change in colour of litmus paper, H⁺ is required because the reaction involved between litmus paper and dry HCl requires equilibrium between dissociated and undissociated molecules using H⁺.