Chapter 7, Problem 76E

Interpretation Introduction

Interpretation: The mass of KOH that is required to prepare 800.0 mL of a solution with pH 11.56 needs to be determined.

Concept Introduction: A base is the substance that gives ${\text{OH}}^{\text{-}}$ ions in its aqueous solution. On the basis of base dissociation, acids can be classified as strong and weak base. A strong base is ionized completely and gives the respective ions.

  ${\text{BOH}}_{\text{(aq)}}\stackrel{}{\to }{\text{B}}^{+}{}_{\text{(aq)}}+{\text{OH}}^{\text{-}}{}_{\text{(aq)}}$

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

  ${\text{BOH}}_{\text{(aq)}}\rightleftharpoons {\text{OH}}^{\text{-}}{}_{\text{(aq)}}{\text{+B}}^{\text{-}}{}_{\text{(aq)}}$

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:

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