Acid ionization reaction

An acid ionization reaction is a reaction in which an H⁺ separates from the acid molecule so that it can be donated in another reaction. The chemical equation for a general acid ionization reaction is as follows:

$HA\rightleftharpoons H^{+}+A^{-}$

Technically, H⁺ doesn't exist in water, it combines with water to form H₃O⁺. Thus, a more accurate general equation would be:

$HA+H_{2}O\rightleftharpoons H_{3}O^{+}+A^{-}$

In most uses, however, the first form of the equation is used, for simplicity.