Question

Dry HCl gas does not change the colour of dry blue litmus paper. Why?

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

Answer 1

The only thing that affects a substance's pH are its ions. In the presence of water, HCl produces hydrogen ions. In the absence of water, the H⁺ ion and HCl molecules cannot be separated. Because dry HCI lacks H⁺ ions, it does not exhibit the characteristics of an acid.