Question

Degree of hydrolysis for a salt of strong acid and weak base is:
A. independent of dilution
B. increases with dilution
C. increase with decrease in ${K_b}$ of the bases
D. decreases with decrease in temperature

Answer 1

The degree of hydrolysis for a salt of strong acid and weak base is inversely proportional to the dissociation constant of the base. Thus, the degree of hydrolysis increases with a decrease in the value of $K_b$.

Complete step by step answer:
The degree of hydrolysis of a salt is defined as the proportion of the salt which is hydrolyzed at equilibrium and what proportion of the salt dissociates into its corresponding ions, as soon as it is dissolved in the water.
For a salt of strong acid and weak base, the relation between the degree of hydrolysis and $K_b$ can be written as:
$h = \sqrt {\dfrac{{{K_W}}}{{{K_b} \times C}}}$
In this relation, h = degree of hydrolysis of the salt
C= Concentration of the solution
${K_W}$ = ionic product of water
The degree of hydrolysis for the salt of a strong acid and weak base increases with an increase in the temperature and with dilution. In the above relation, it is clearly visible that the degree of hydrolysis for a salt of strong acid and weak base is inversely proportional to the dissociation constant of the base ($K_b$).
Hence, the correct option is C i.e increase with decrease in $K_b$ of the bases.

Note:
Whenever a salt of strong acid and weak base is dissolved in water, it undergoes dissociation and forms its corresponding oppositely charged ions. But, it cannot undergo complete dissociation and thus, depends on its degree of hydrolysis which decides how much part of the salt is actually reactive.