Enthalpy of solution of copper (ii) sulfate pentahydrate The enthalpy of hydration is difficult to calculate as it is not possible to measure the chemical potential energy directly as the CuSO4.5H2O crystallizes. Using Hess's Law you will then work out the ΔH of equation 3. This has two parts.   Part one reverse equation 1 Part two add it to equation 2. Step 1 measure the mass of a crucible 72.468 grams Step 2 Measure accurately about 23.0 g of copper sulfate pentahydrate (CuSO4.5H2O ) 95.76 - 72.468 = 23.29 grams Step 3 Add 100 mL of distilled water to the calorimeter Step 4 Measure the temperature of the water. 18.10 oC Step 5 Add the CuSO4.5H2O to the water and seal the calorimeter. Stir the the water to allow for the CuSO4.5H2O to dissolve. Step 6 Record the final temperature of the water. 15.50 oC Step 7 Calculate the ΔH. of the reaction below CuSO4 .5H2O (s) + (aq) => CuSO4(aq) + H2O(l) ΔH = Step 1 calculate the mol of copper sulfate pentahydrate => 23.29 / 250.0 = 0.0932 Step 2 Calculate the change in temperature ΔT (18.10 - 15.50 ) = 2.6 oC Step 3 Calculate the amount of energy released => Energy = 4.18J/g/C X 100g X 2.6 oC = 1087 J Step 4 Calculate the ΔH = 1087 / 0.0932 = + 11.7 kJ/mol