The heat of solution of anhydrous `CuSO_(4)` is `-66.5` kJ and that of `CuSO_(4).5H_(2)O` is 11.7 kJ . Calculate is the heat of hydration of `CuSO_(4)`.

Explanation

According to Hess's Law - `Delta H = Delta H_(1)+Delta H_(2)`
`-66.5 kJ = Delta H_(1)+11.7 kJ`
`Delta H_(1)=-78.2 kJ`