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

$H - X + {H}_{2} O r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + {X}^{-}$
If the equilibrium lies strongly to the right, $H X$ is considered to be a strong acid. All the hydrogen halides, save $H F$, are considered to be exceptionally strong acids, and their aqueous solutions are stoichiometric in ${H}_{3} {O}^{+}$.