Chapter 19.3, Problem 29LC

Interpretation Introduction

Interpretation : The acids in the table that have the lowest dissociation constant are to be concluded.

Concept Introduction : The acid dissociation constant is the ratio of an acid's dissociated form concentration to its undissociated form concentration. It is denoted as ${\text{K}}_{\text{a}}$ .

Answer to Problem 29LC

The acid in the table that has the lowest dissociation constant is hypochlorous acid.

Explanation of Solution

In general, the dissociation of acid HA is written as follows:

  $HA\rightleftharpoons H^{+}+A^{-}$

The dissociation constant ${\text{K}}_{\text{a}}$ of the acid HA is written as,

  ${\text{K}}_{\text{a}}=\frac{\left[H^{+}\right]\left[A^{-}\right]}{\left[HA\right]}$

The strength of the acid is directly proportional to the acid dissociation constant.

The stronger the acid, the higher will be the acid dissociation constant.

The table contains acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, ethanoic acid, carbonic acid, and hypochlorous acid.

Among the acids given, hydrochloric acid is the strongest acid which will have a higher dissociation constant.

Hypochlorous acid is the weakest acid that has the lowest dissociation constant.