Question

In an aqueous solution of $N{{H}_{4}}Cl$
A. Anionic Hydrolysis takes place
B. $pH$ of the solution is greater than 7
C. It turns red litmus to blue
D. ${{K}_{h}}=\dfrac{{{K}_{w}}}{{{K}_{a}}}$
(A) A and D are correct
(B) All are correct
(C) B and C are correct
(D) All are wrong

Answer 1

In anionic hydrolysis, pH is less than 7. Hydrochloric acid is a strong acid. The base turns red litmus blue. For acidic solutions, $pH$is less than 7. ${{K}_{h}}=\dfrac{{{K}_{w}}}{{{K}_{a}}}$is applicable to hydrolysis of salt of a weak acid and strong base.

Complete step by step solution:
- When ammonium chloride undergoes hydrolysis, ammonium cation reacts with Hydroxyl ion of water to produce ammonium hydroxide. Ammonium Hydroxide is a weak base so it does not dissociate completely. Chloride ion reacts with hydrogen to produce Hydrochloric acid. Hydrochloric acid is a strong acid so it dissociates completely.
In salt hydrolysis, cation or anion or both ions of salt react with water and produce an acidic or basic or neutral solution.
When anion or cation of salt reacts with water, the $O-H$ bond is cleaved, which is known as hydrolysis.
-There are two types:
Anionic Hydrolysis- Anion reacts with water to cleave $O-H$ bond
Cationic Hydrolysis-Cation reacts with water to cleave $O-H$ bond
Ammonium ions react with Hydroxyl ions to form ammonium hydroxide and hydrogen ions are produced which leads to a decrease in the concentration of Hydroxyl ions and an increase in the concentration of hydrogen ions which makes the resultant solution acidic. Ammonium ion cleves $O-H$ bond, ammonium ion undergoes cationic hydrolysis.
The acidic solution turns litmus blue to red.
Acidic solutions have $pH$ less than 7.
${{K}_{h}}=\dfrac{{{K}_{w}}}{{{K}_{a}}}$ is applicable to hydrolysis of salt of the weak acid and strong base.

So, (D) All are wrong.

Note: In Anionic Hydrolysis, Anion reacts with water to cleave O-H bond. The acidic solution turns litmus blue to red. Acidic solutions have $pH$less than 7. Ammonium chloride is salt of strong acid hydrochloric acid and weak base ammonium hydroxide. Salt of strong acid and a weak base produces the acid solution.