Chapter 19.5, Problem 50LC

Interpretation Introduction

Interpretation : The chemical equations are to be written showing what happens when acid and base are added to an ammonium ion-ammonia buffer.

Concept Introduction : A buffer is a solution that retains the pH of a solution irrespective of the addition of small amounts of acids or bases.

Answer to Problem 50LC

The chemical equation taken place between the buffer and acid and base is given below:

  ${\text{NH}}_{\text{3}}+{\text{H}}^{\text{+}}\rightleftharpoons {\text{NH}}_{\text{4}}^{\text{+}}$

  ${\text{NH}}_{\text{4}}^{\text{+}}+{\text{OH}}^{-}\rightleftharpoons {\text{NH}}_{\text{3}}+{\text{H}}_{\text{2}}\text{O}$

Explanation of Solution

A weak acid and one of its salts or a weak base and one of its salts are solutions that are used as buffers.

Buffers are formed by the combination of weak acids or bases with their respective salts.

The buffer solution is ammonium ion-ammonia.

The ammonium ion reacts with the base to give ammonia and water. Since ammonium ion is a conjugate acid, it leaves its hydrogen ion.

  ${\text{NH}}_{\text{3}}+{\text{H}}^{\text{+}}\rightleftharpoons {\text{NH}}_{\text{4}}^{\text{+}}$

The ammonia reacts with an acid to give an ammonium ion. Since ammonia is a conjugate base, it consumes hydrogen ions.

  ${\text{NH}}_{\text{4}}^{\text{+}}+{\text{OH}}^{-}\rightleftharpoons {\text{NH}}_{\text{3}}+{\text{H}}_{\text{2}}\text{O}$