Question

A weak acid $HX$ has the dissociation constant $1\times {{10}^{-5}}\text{ }M.$ It forms a salt NaX on reaction with alkali. The percentage hydrolysis of $0.1\text{ }M$ solutions of $NaX$ is:
A.$0.0001$
B.$0.01$
C.$0.1$
D.$0.15$

Answer 1

We know that both acid and base are weak, then neither of them dissociate completely so neutralization reaction does not take place. They remain in equilibrium which is a state in which the rate of formation of reactant is equal to the rate of formation of product.

Complete answer:
As we know, the degree of hydrolysis is the cleavage of peptide bonds in the protein hydrolysate. Degree of dissociation is the phenomenon in which free ions are generated which carry current, which are dissociated from the fraction of solute at a given concentration. The degree of dissociation for strong acid and base is equal to one since they completely dissociate in water. The compound given here was a weak acid. Sodium halide is a weak acid and strong basic salt and so that, the hydrolysis of sodium halide is taken by; $h=\sqrt{\dfrac{{{K}_{w}}}{{{K}_{a}}\times C}}$ on substitution we get $h=\sqrt{\dfrac{{{10}^{-14}}}{{{10}^{-5}}\times 0.1}}.$
On further solving we get; $h=\dfrac{{{10}^{-14}}}{{{10}^{-5}}\times {{10}^{-2}}}=\dfrac{{{10}^{-14}}}{{{10}^{-10}}}={{10}^{-4}}.$
Thus, the percentage of hydrolysis is given by ${{10}^{-14}}\times 100=0.01$ Also, the strong acids such as the mineral acids, dissociate completely and therefore they do not require a representation at equilibrium. The dissociation per cent for a strong acid is always hundred percent.

Therefore, the correct answer is option B.

Note:
Remember that the salts formed from the neutralization reaction between a strong base and weak acid are basic salts. The pH of an aqueous solution of such salt is more than seven. Salts resulting from the neutralization reaction between a weak acid and weak base can be mildly basic, mildly acidic, or neutral depending on the nature of the bases and acids involved.