Question

Why is hydrochloric acid (`HCl`) classified as a strong acid?

Answer 1

Because of its dissociation in water.

Explanation:

The strength of an acid is determined by the extent of the following equilibrium:

`H-X + H_2O rightleftharpoons H_3O^+ + X^-`

If the equilibrium lies strongly to the right, `HX` is considered to be a strong acid. All the hydrogen halides, save `HF`, are considered to be exceptionally strong acids, and their aqueous solutions are stoichiometric in `H_3O^+`.