Calculate the enthalpy of hydration of anhydrous copper sulphate `(CuSO_(4).5H_(2)O)`. Given that the enthalpies of solutions of anhydrous copper sulphate and hydrated copper sulphate are -66.5 and +11.7 KJ `mol^(-1)` respectively

Explanation

We are given
(i) `(CuSO_(4).5H_(2)O)`
`Delta_("sol")H=-66.5KJmol^(-1)`
(ii) `CuSO_(4).5H_(2)O_((s))+aqrarrCuSO_(4)(aq)`
`Delta_("sol")H=-66.5KJmol^(-1)`
(ii) `CuSO_(4).5H_(2)O_((s))+aqrarrCuSO_(4)(aq)`
`Delta_(sol)H=+11.7KJmol^(-1)`
We need
`CuSO_(4(s))+5H_(2)O_((l))rarrCuSO_(4).5H_(2)O_((s)),Delta_(hyd)H=?`
Substracting equation (ii) from equation (i). we get
`CuSO_(4(s))+5H_(2)O_((l))rarrCuSO_(4).5H_(2)O_((s))`
`Delta_(hyd)H=-78.2KJmol^(-1)`