It is the reaction of the cation or the anion or both the ions of the salt with water to produce either acidic or basic solution. Hydrolysis is the reverse of neutralization.
Salt Aqueous solution
(1) Hydrolysis constant: The general equation for the hydrolysis of a salt (BA), ⇌
|Types of salt||Exp. for Kh||Exp. for h||Exp. for pH|
|(i) Salt of weak acid and strong base||Kh=Kw / Ka||pH=–[log Kw+log Ka– log C]|
|(ii) Salt of strong acid and weak base||Kh=Kw / Kb||pH=–[log Kw– log Kb+ log C]|
|(iii) Salt of weak acid and weak base||pH=–[log Ka+ log Kw– log Kb]|
Applying the law of chemical equilibrium, we get
, where K is the equilibrium constant.
Since water is present in very large excess in the aqueous solution, its concentration may be regarded as constant so,
where is called the hydrolysis constant.