Chapter 12, Problem 12.133QP

The lattice enthalpy of sodium chloride, ΔH° for

$\text{NaCl}(s)\to {\text{Na}}^{+}(g)+{\text{Cl}}^{-}(g)$

is 787 kJ/mol; the heat of solution in making up 1 M NaCl(aq) is +4.0 kJ/mol. From these data, obtain the sum of the heats of hydration of Na⁺ and Cl⁻. That is obtain the sum of ΔH° values for

$\begin{array}{c}{\text{Na}}^{+}(g)\to {\text{Na}}^{+}(aq)\\ {\text{Cl}}^{-}(g)\to {\text{Cl}}^{-}(aq)\end{array}$

If the heat of hydration of Cl⁻ is −338 kJ/mol, what is the heat of hydration of Na⁺?