Chapter 16.10, Problem 3Q

Interpretation Introduction

Interpretation:

The equation for the reaction of an amide ion with water has to be writtern and the reaction is reactant or product favored at equilibrium has to be exlained.

Concept introduction:

An equilibrium constant $\left(K\right)$ is the ratio of the concentration of products and reactants raised to appropriate stoichiometric coefficient at equilibrium.

The reaction of an acid HA with water is written as,

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

The relative strength of an acid and base in water can be also expressed quantitatively with an equilibrium constant as follows:

$K_{\text{a}}=\frac{\left[{\text{H}}_{\text{3}}{\text{O}}^{+}\right]\left[{\text{A}}^{-}\right]}{\left[\text{HA}\right]}$

An equilibrium constant $\left(K\right)$ with subscript $\text{a}$ indicates that it is an equilibrium constant of an acid in water.

The reaction of any base B with water is written as,

  $\text{B}\left(\text{aq}\right)+{\text{H}}_{\text{2}}\text{O}\left(\text{l}\right)\rightleftharpoons \text{BH}\left(\text{aq}\right)+{\text{OH}}^{-}\left(\text{aq}\right)$

The relative strength of an acid and base in water can be also expressed quantitatively with an equilibrium constant as follows:

$K_{\text{b}}=\frac{\left[\text{BH}\right]\left[{\text{OH}}^{-}\right]}{\left[\text{B}\right]}$

An equilibrium constant $\left(K\right)$ with subscript $\text{b}$ indicates that it is an equilibrium constant of the base in water.