Calculation enthalpy of solution

Question

Hi!

I have calculated the enthalpy of solution for hydrous copper sulfate but I dont know if I did it right or wrong. Can someone please check for me?

Calculations for solution of CuSO4 * 5 H2O

m(CuSO4*5H2O)= 2.04 g

V(H2O)= 25 cubic cm= 25 g

m(solution)= 27.04 g

Change in temperature= 19 deg. Celsius- 19.6 deg. Celsius= 0.6 K (endothermic reacton, because temperature decreased)

c= 4.2 J / (g * K)

E= 4.2 * 0.6 * 27.04 = 68 J.

68 Joules has been needed for this reaction.

To get how much energy is needed when solving 1 moles of CuSO4 * 5 H2O I divide the amount of energy for this reaction with the amount of moles of the hydrous copper sulfate I have.

n= m/M

n= 2.04/249.7 = 0.0082 moles

delta H= 68/0.0082 = 8.3 kJ/mole

My answer is 8.3 kJ/mole, but I dont know if I did the calculation correct and if it is correct in comparsion to values from other sources. Can someone please help me?

Answer 1

Yes, you did this correctly. I didn't check all of the math, but I, too, came up with 67.9 J for the reaction. Then it is just a matter of finding moles and dividing, which I assume you did correctly.

The literature value that I was able to find was 11.3 kJ/mole, so your answer is in line with that. Nice job.