The heat of solution of anhydrous CuSO4 is - 15.9 kcal and that of CuS04.5H2O is 2.8 kcal. Calculate the heat of hydration of CuSO4.

CuSO4+aq→CuSO4⋅5H2O (aq);  ΔH=−15.9kcalCuSO4⋅5H2O+aq→CuSO4⋅5H2O(aq)ΔH=2.8kcal Subtracting (2) from (1), we get CuSO4+5H2O→CuSO4⋅5H2O; ΔH=−15.9−2.8= -18.7 kcal.'. Heat of hydration of CUSO4 = - 18.7 kcal