Question

Potassium perchlorate has a lattice energy of -599 kj/mol and a heat of hydration of -548 kj/mol.

Find the heat of solution for potassium perchlorate when 10.6 g of potassium perchlorate is dissolved with enough water to make 102.7 ml of solution. (J-absorbed)

find the temperature change that occurs when 10.6 g of potassium perchlorate is dissolved with enough water to make 102.7 ml of solution. (Assume a heat capacity of 4.05 J/g*C for the solution and a density of 1.05 g/ml.)

Answer 1

It will take 599 kJ/mol to break the lattice. It will get back 548 kJ/mol in hydration energy. Therefore, the net loss per mol KClO4 is 599-548 = 51 kJ/mol which is the amount of energy that must be added. I assume your note for J-absorbed means that. Convert 10.6 g KClO4 to moles, then use
q = mass x specific heat x delta T and calculate delta T. Post your work if you need further assistance.