Chapter 16, Problem 18QAP

Interpretation Introduction

Interpretation:

What does it mean to say that an acid is weak in aqueous solution should be discussed? What does this reveal about the ability of the acid’s anion to attract protons should be discussed?

Concept Introduction:

When an acid dissolves in water, a proton is transferred from the acid to water. (Forward reaction)

${\text{HA}}_{\text{(aq)}}{\text{+H}}_{\text{2}}{\text{O}}_{\text{(l)}}\to {\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{}_{\text{(aq)}}{\text{+A}}^{\text{-}}{}_{\text{(aq)}}$

In this reaction conjugate acid H₃ O+ and conjugate base A- is produced. This conjugate acid and conjugate base can react with each other. (Backward reaction)

${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{}_{\text{(aq)}}{\text{+A}}^{\text{-}}{}_{\text{(aq)}}\to {\text{HA}}_{\text{(aq)}}{\text{+H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

This reaction reforms the acid and water.

Therefore the reaction can occur in both directions; Forward and reverse directions.

${\text{HA}}_{\text{(aq)}}{\text{+ H}}_{\text{2}}\text{O}\rightleftharpoons {\text{H}}_{\text{3}}{\text{O}}^{\text{+}}{}_{\text{(aq)}}{\text{+ A}}^{\text{-}}{}_{\text{(aq)}}$

Products of the forward reaction are the reactants of reverse reaction.