Which acid is stronger, hypochlorous acid or hydrochloric acid?

Hydrochloric acid is stronger than hypochlorous acid due to its higher degree of dissociation in water. When hydrochloric acid (HCl) is dissolved in water, it fully dissociates into hydrogen ions (H⁺) and chloride ions (Cl⁻), making it a strong acid. This complete dissociation results in a higher concentration of H⁺ ions in solution, which is what defines an acid's strength.

In contrast, hypochlorous acid (HOCl) is a weaker acid. It does not fully dissociate in water; instead, it establishes an equilibrium where only a portion of the acid molecules break apart into H⁺ and hypochlorite ions (OCl⁻). This limited dissociation means that the concentration of H⁺ ions in a solution of hypochlorous acid is much lower than in a solution of hydrochloric acid, thereby making hypochlorous acid a weaker acid.

Understanding the differences in dissociation behavior helps clarify why hydrochloric acid is considered the stronger acid in this comparison.