Chapter 5, Problem 5.39E

The bisulfate (or hydrogen sulfate) anion, ${\text{HSO}}_4{}^{-}$, is a weak acid. The equilibrium constant for the aqueous acid reaction

${\text{HSO}}_4{}^{-}\left(\text{aq}\right)\rightleftharpoons {\text{H}}^{+}\left(\text{aq}\right)+{\text{SO}}_4{}^{2-}\left(\text{aq}\right)$ is $1.2\times {10}^{-2}$.

(a) Calculate $\Delta G°$ for this equilibrium. Assume a temperature of $25.0°\text{C}$.

(b) At low concentrations, activity coefficients are approximately $1$ and the activity of a dissolved solute equals its molality. Determine the equilibrium molalities of a $0.010$-molal solution of sodium hydrogen sulfate.