I have to measure the enthalpy change for the reaction: CuSO4(s) + 5H2O --> CuSO4 · 5H2O I have to use the hess law since the above reaction is slow. CuSO4 · 5H2O + H2O --> CuSO4 + H2O (1) solid CuSO4 + H2O --> CuSO4 (2) The techer said the entalphy change for this reaction should be -79kJ/mol and the heat capacity of the solution should be taken as 4.2 kJ/mol. However when I react 50 cm3 water with 0.025 moles CuSO4 · 5H2O in equation 1, I get a temperature change of -0.8 C. In the second reaction, 50cm3 of water reacted with 0.025mol of CuSO4. Here the temperature change was +6.5 C. But when I plug it into the equation E = m c ∆t; I get an endothermic value. What is wrong? Should the reaction 2 be exothermic?