Chapter 15, Problem 1SAQ

Interpretation Introduction

Introduction: According to the theory given by Bronsted and Lowry, a conjugate base is formed when an acid donates/loses a hydrogen ion.

Answer to Problem 1SAQ

Correct answer: The conjugate base in the given reaction is ${\text{ClO}}_{\text{2}}{}^{-}$.

Therefore, option (d) is correct.

Explanation of Solution

Justification for the correct option:

When an acid donates its hydrogen ion, a conjugate base is formed.

Consider the given reaction:

${\text{HClO}}_{\text{2}}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{aq}\right)\to {\text{H}}_{\text{3}}{\text{O}}^{\text{<mo>+</mo>}}\left(\text{aq}\right)+{\text{ClO}}_{\text{2}}^{-}\left(\text{aq}\right)$

The acid ${\text{HClO}}_{\text{2}}$ loses one proton and forms ${\text{ClO}}_{\text{2}}^{-}$, which is a conjugate base.

Justification for incorrect options:

The base ${\text{H}}_2\text{O}$ accepts a hydrogen ion and forms ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$.The ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ formed is a conjugate acid. Moreover, ${\text{HClO}}_{\text{2}}$ is an acid, which forms a conjugate base.

Hence, options (a), (b), and(c) are incorrect.

Conclusion

A conjugate base is formed when an acid donates a hydrogen ion. In case of stronger acid, a weaker conjugate base is formed. Simultaneously, weak acids form a strong base.