Long Answer TypeDiscuss the salt hydrolysis in the following cases:
(i) Salts of strong acid and strong base
(ii) Salts of strong acid and weak base
(iii) Salts of weak acid and strong base
(iv) Salts of weak acid and weak base.
Short Answer TypeLong Answer TypeExplain 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%.
Derive the relation,
in the case of hydrolysis of salts of strong acids and weak acids.
Show that for an aqueous solution of a salt of weak base and strong acid 
where 
is the degree of hydrolysis.
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