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