Chapter 7, Problem 94E

Interpretation Introduction

Interpretation : The concentration of carbonate ion needs to be determined in the 0.010 M of carbon dioxide in water. The percentage of hydrogen ions in the solution from dissociation of ${\text{HCO}}_3^{-}$ ions needs to be determined. The reaction of sodium hydrogen carbonate with acid needs to be explained.

Concept Introduction: An acid is the substance that gives H+ or ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ ions in its aqueous solution. A strong acid ionized completely to form respective ions whereas 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 number of hydrogen ions given by an acid can be different from other acid. On the basis of number of hydrogen ion given by an acid, they can be classified as monoprotic, diprotic and triprotic acids.

The acid dissociation constants of ${\text{H}}_2{\text{CO}}_3$ and ${\text{HCO}}_3^{-}$ are as follows:

  $\begin{array}{l}{\text{H}}_2{\text{CO}}_3\rightleftharpoons {\text{ H}}^{+}{\text{ + HCO}}_3^{-}{\text{ K}}_{a1}=4.3\times {10}^{-7}\\ {\text{HCO}}_3^{-}\rightleftharpoons {\text{ H}}^{+}{\text{ + CO}}_3^{2-}{\text{ K}}_{a2}=4.8\times {10}^{-11}\end{array}$