$15\mathrm{.}7.$ The partial pressures of water over sodium nitrate solutions are shown below at various

temperatures and compositions.

$2$The solution is saturated.

In addition, the following data are available for saturated solutions of $NaN{O}_3.$

Determine the enthalpy change for crystallization at $25C.$

$H_{\text{c}\text{r}\text{y}}=x_{H_{2}O}(H^L\frac{-}{b}ar(H{)}^L{)}_{H_{2}O}+x_{NaN{O}_3}(H^S\frac{-}{b}ar(H{)}^L{)}_{NaN{O}_3}$

Also calculate $(H^S\frac{-}{b}ar(H{)}^l{)}_{NaN{O}_3}$ at $25C,$ saturated solution.