Chapter 10, Problem 10.1P

Interpretation Introduction

Interpretation:

The given statement has to be explained (the ${\text{K}}_{\text{a}}$ and ${\text{K}}_{\text{b}}$ reactions proceed to nearly the same extent when $\text{NaHA}$ is dissolved in water).

Concept introduction:

Weak-acid equilibrium:

The acid dissociation constant, ${\text{K}}_{\text{a}}$ for the acid $\text{HA}$

$\begin{array}{l}\text{HA}\stackrel{{\text{K}}_{\text{a}}}{\rightleftharpoons }{\text{H}}^{\text{+}}{\text{+A}}^{\text{-}}\\ {\text{K}}_{\text{a}}\text{=}\frac{\left[{\text{H}}^{\text{+}}\right]\left[{\text{A}}^{\text{-}}\right]}{\left[\text{HA}\right]}\end{array}$

A weak acid is not completely dissociated.

Weak-base equilibrium:

The acid dissociation constant, ${\text{K}}_{\text{b}}$ for the acid $\text{B}$

$\begin{array}{l}\text{B}\text{+}{\text{H}}_{\text{2}}\text{O}\stackrel{{\text{K}}_{\text{b}}}{\rightleftharpoons }{\text{BH}}^{\text{+}}{\text{+OH}}^{\text{-}}\\ {\text{K}}_{\text{b}}\text{=}\frac{\left[{\text{BH}}^{\text{+}}\right]\left[{\text{OH}}^{\text{-}}\right]}{\left[\text{B}\right]}\end{array}$