Question

A buffer solution is prepared by adding NH4Cl to a solution of NH3 (ammonia). what happens if NaOH is added?

Answer 1

Answer: The reaction proceeds in the backward direction.

Explanation:

A buffer is a solution that maintains the pH of the solution and resists any significant changes of pH on the addition of acid or alkali.

A buffer solution of $NH_4Cl\text{ and }NH_3$ is prepared. It is a basic buffer as it is formed by the combination of a weak base $(NH_3)$ and its conjugate acid $(NH_4Cl)$

When a strong base (NaOH) is added to this buffer solution, the ammonium ions releases hydrogen ion to the solution which then combines with the hydroxide ions to form water and ammonia in a solution. Thus, maintaining the pH of the buffer.

The given chemical equation follows:

$NH_3(aq)+H_2O(l)\rightleftharpoons NH_4^+(aq)+OH^-(aq)$

Hence, the reaction will proceed in the backward direction.