Chapter 16.7, Problem 4RC

Interpretation Introduction

Interpretation:

The $\text{pH}$ range should be identified given the statement of equilibrium reaction.

Concept introduction:

$pH$ concept of hydronium ions: A strong acid completely dissociates into its constituent ions in aqueous solution, as a result, the concentration of its ion is same as the initial concentration of that strong acid.

For example, strong acid dissociates as follows in water,

$\text{HA}\left(\text{aq}\right)+{\text{H}}_2\text{O}\left(\text{l}\right)\rightleftharpoons {\text{H}}_3{\text{O}}^{+}\left(\text{aq}\right)+{\text{A}}^{-}\left(\text{aq}\right)$

$\left[{\text{H}}_3{\text{O}}^{+}\right]=\left[{\text{A}}^{-}\right]=\left[\text{HA}\right]$

The $\text{pH}$ of a solution is basically the measure of the molar concentration of the ${\text{H}}^{+}$ or ${\text{H}}_3{\text{O}}^{+}$ ion in the solution. More the concentration of ${\text{H}}^{+}$ or ${\text{H}}_3{\text{O}}^{+}$ ion in the solution, lesser will be the $\text{pH}$ value and more acidic will be the solution.

The expression for $\text{pH}$ is given as,

$\text{pH}=-\text{log}[{\text{H}}_3{\text{O}}^{+}]$

The concentration of ${\text{OH}}^{-}$ ions is calculated by using the ionic product of water.

$K_{\text{w}}=[{\text{H}}_3{\text{O}}^{+}][{\text{OH}}^{-}]$

The value of $K_{\text{w}}$ is $1.0\times {10}^{-14}$.

If $\text{pH}<7$ then, the solution is acidic in nature.

If $\text{pH}<7$ then, the solution is basic in nature.

If $\text{pH}<7$ then, the solution is neutral in nature.