There are two types of acids. Strong and weak. $^{\text{2:67}}$

In general, the difference between a strong and a weak acid is the amount it dissociates or breakes up ions in water. $^{\text{2:68}}$

$$ HCl(aq) \xrightarrow[\text{}] {\text{100\%}} H^+(aq) + Cl^-(aq) $$

HCl is a strong acid. As a result, it fully dissociates in water before reaching an equilibrium. The Chlorine ions have no affinity to the Hydrogen ions in water. As a result the reaction is irreversible.$^{\text{2:68}}$

Weak acids do not fully dissociates in water before reaching an equilibrium. For example, Ethanoic acid($CH_3COOH$), whose common name is acetic acid.

$$ CH_3COOH(aq) \xrightleftharpoons[\text{}]{\text{<100\%}} H^+(aq) + CH_3COO^-(aq) $$