CBSE Class 11-science Answered

A hydrolysis constant is an equilibrium constant for a hydrolysis reaction.

For example, if a metal salt such as AlCl₃ dissolves in an aqueous solution, the metal cation behaves as a Lewis acid and hydrolyzes the water molecules in the solvent.

Al³⁺ + 2H₂O → AlOH²⁺ + H₃O⁺

The hydrolysis constant for this reaction is as shown:

K_hydrolysis = [H₃O⁺] * [AlOH²⁺] / [Al³⁺]

In a more generalized form, the hydrolysis constant can be described as:

K_a = [H₃O⁺] * [A⁻] / [HA]

Where A− represents any base, and HA represents any acid.