Question

What makes `HCl` a strong acid?

Answer 1

The protonolysis reaction lies strongly to the right.

Explanation:

As an acid, hydrochloric acid undergoes protonolysis in water as shown:

`HCl(aq) + H_2O(l) rightleftharpoons H_3O^+(aq) + Cl^(-)(aq)`

This equilibrium lies strongly, almost quantitatively to the right, and it is the position of this equilibrium that justifies our designation of `HCl` as a strong acid.

O the other hand, for the congeneric hydrogen fluoride:

`HF(aq) + H_2O(l) rightleftharpoons H_3O^+(aq) + F^(-)(aq)`,

this equilibrium lies to the LEFT HAND SIDE, and `HF` is not considered to be a strong Bronsted acid.