Chapter 20, Problem 56E

Phosphate buffers are important in regulating the pH of intracellular fluids. If the concentration ratio of H₂PO₄⁻/HPO₄²⁻ in a sample of intracellular fluid is 1.1: 1, what is the pH of this sample of intracellular fluid?

${\text{H}}_{\text{2}}{\text{PO}}_{\text{4}}{}^{-}\left(aq\right)\rightleftharpoons {\text{HPO}}_{\text{4}}{}^{2-}\left(aq\right)+{\text{H}}^{\text{+}}\left(aq\right)K_a=6.2\times {10}^{-8}$