Question

Why do acids not show acidic behaviour in the absence of water?

Answer 1

Acids do not show acidic behaviour in the absence of water because the dissociation of hydrogen ions from an acid occurs only in the presence of water. It is the hydrogen ions that are responsible for the acidic behaviour.

Answer 2

Acids ionise only in the presence of water to give ions.
\[\ce{HCl + H2O -> H3O+ + Cl-}\]
However, in the absence of water, acids do not ionise to give H₃O⁺ ions and therefore, do not behave as acids.