Question

Why is hcl gas unable to change the color of dry blue litmus paper?
What happens when the litmus paper is moistened?

Answer 1

Hello dear friend !

Here is your answer :-

HCl gas gives h + ions only in aqueous solution.So it will not split into h + + Cl- in the dry Litmus Paper no reaction occur.

With which Litmus Paper water acts as a career for splitting the HCL into h + + Cl-, then reaction occurs and turn the blue .itmus into red.

Answer 2

It is because HCl gas is dry and there is no movement of ions in it. When litmus paper is moistened the gas becomes wet again and changes its colour.