Chapter 7, Problem 43E

(a)

Interpretation Introduction

Interpretation: The pH of 0.10 M HCl in water needs to be determined.

Concept Introduction: An acid is the substance that gives H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in its aqueous solution. On the basis of acid dissociation, acids can be classified as strong and weak acid. A strong acid is ionized completely and gives the respective ions.

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

On the contrary, a weak acid ionized partially and reaches to equilibrium.

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

The pH value depends on the concentration of H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in the solution. The mathematical relation between pH and H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions can be written as:

  ${\text{pH = - log [H}}_{\text{3}}{\text{O}}^{\text{+}}]$

(b)

Interpretation Introduction

Interpretation: The pH of $\text{1}\text{.0}\times {\text{10}}^{\text{-11}}\text{M}$ HI in water needs to be determined.

Concept Introduction: An acid is the substance that gives H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in its aqueous solution. On the basis of acid dissociation, acids can be classified as strong and weak acid. A strong acid is ionized completely and gives the respective ions.

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

On the contrary, a weak acid ionized partially and reaches to equilibrium.

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

The pH value depends on the concentration of H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in the solution. The mathematical relation between pH and H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions can be written as:

  ${\text{pH = - log [H}}_{\text{3}}{\text{O}}^{\text{+}}]$

(c)

Interpretation Introduction

Interpretation: The pH of $5.0\text{M}$ HClO₄in water needs to be determined.

Concept Introduction: An acid is the substance that gives H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in its aqueous solution. On the basis of acid dissociation, acids can be classified as strong and weak acid. A strong acid is ionized completely and gives the respective ions.

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

On the contrary, a weak acid ionized partially and reaches to equilibrium.

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

The pH value depends on the concentration of H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in the solution. The mathematical relation between pH and H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions can be written as:

  ${\text{pH = - log [H}}_{\text{3}}{\text{O}}^{\text{+}}]$