The heat of solution of anhydrous CuSO_4 and CuSO_4 · 5 H_2 O are -70 kJ mol^-1 and +12 kJ mol^-1 respectively. The heat of hydration of CuSO_4 to…

The heat of solution of anhydrous $\displaystyle \mathrm{CuSO}_4$ and $\displaystyle \mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O}$ are $\displaystyle -70 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\displaystyle +12 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The heat of hydration of $\displaystyle \mathrm{CuSO}_4$ to $\displaystyle \mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O}$ is $\displaystyle -x \mathrm{~kJ}$. The value of $\displaystyle x$ is $\displaystyle \_\_\_\_$. (nearest integer).