Chapter 6, Problem 6.52QP

The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H⁺ ions; that is, $\Delta H_{\text{f}}^{\text{o}}[\text{H}+(aq)]=0$.

1. (a) For the following reaction $\begin{array}{l}\text{HCl}(g)\stackrel{{\text{H}}_2\text{O}}{\to }{\text{H}}^{+}(aq)+{\text{Cl}}^{-}(aq)\hfill \\ \Delta H^{\text{o}}=-74.9\text{kJ/mol}\hfill \end{array}$ calculate $\Delta H_{\text{f}}^{\text{o}}$ for the Cl⁻ ions.
2. (b) Given that $\Delta H_{\text{f}}^{\text{o}}$ for OH⁻ ions is −229.6 kJ/mol, calculate the enthalpy of neutralization when 1 mole of a strong monoprotic acid (such as HCl) is titrated by 1 mole of a strong base (such as KOH) at 25°C.