Explain the following terms:
(i) Hydrolysis constant
(ii) Degree of hydrolysis.

(i) Hydrolysis constant:
Hydrolysis of a salt (BA) may be represented as
                      
Applying the law of chemical equilibrium, we get, 
                    
Since water is present in very large excess in aqueous solution, its concentration  may be regarded as constant.
                                
Since [HA] and [BOH] represent the molar concentration of the free acid and the free base produced and [BA] represents the molar concentration of the unhydrolyzed salt, the expression for the hydrolysis constant may be written as,

(ii) The degree of hydrolysis: The degree of hydrolysis (α) of a salt is defined as the fraction (or percentage) of the total salt which is hydrolysed. For example, if in a solution of aniline hydrochloride, 90% of the salt is hydrolyzed into aniline and hydrochloric acid, the degree of hydrolysis is 0·90 Or may be expressed as percentage i.e. 90%.