Assertion : A solution of $\mathrm{NH}_4 \mathrm{Cl}$ in water is acidic in nature.\ Reason : Ammon

Question

Assertion : A solution of $\mathrm{NH}_4 \mathrm{Cl}$ in water is acidic in nature.\ Reason : Ammonium ions undergo hydrolysis to form $\mathrm{NH}_4 \mathrm{OH}$.

Professor PC Thomas Classes · Answer

(a) : $\mathrm{NH}_4 \mathrm{Cl}_{(a q)} \rightarrow \mathrm{NH}_{4(a q)}^{+}+\mathrm{Cl}_{(a q)}^{-}$ $\mathrm{NH}_4^{+}$ions formed, undergo hydrolysis with water to form $\mathrm{NH}_4 \mathrm{OH}$ and $\mathrm{H}^{+}$ions. $\mathrm{NH}_4 \mathrm{OH}$ is a weak base and thus remains almost unionised in solution. As a result, $\left[\mathrm{H}^{+}\right]$ions increase in solution, making the solution acidic.