Chapter 16, Problem 84AE

The active ingredient of Pepto-Bismol is the compound bismuth subsalicylate, which undergoes the following dissociation when added to water:

${\text{C}}_{\text{7}}{\text{H}}_{\text{5}}\begin{array}{cc}{\text{BiO}}_{\text{4}}\text{(}s\text{)}\text{+}{\text{H}}_{\text{2}}\text{O(}l\text{)}\rightleftharpoons {\text{C}}_{\text{7}}{\text{H}}_{\text{4}}{\text{O}}_{\text{3}}{}^{\text{2}-}(aq\text{)}\text{+}{\text{Bi}}^{\text{3+}}\text{(}aq\text{)}\text{+}{\text{OH}}^{-}\text{(}aq\text{)}& K=?\end{array}$

If the maximum amount of bismuth subsalicylate that reacts by this reaction is 3.2 × 10⁻¹⁹ mol/L, calculate the equilibrium constant for the preceding reaction.