A sample of 0.75 KCL is added to 35 g of H2O in a calorimeter and stirred until dissolved, the temperature of the solution decreases from 24.8 to 23.6 what is the enthalpy of solution expressed in kJ / mole KCL?

Answer 1

Note that you need to spell chemistry correctly.
The heat of solution which is the heat lost when KCl dissolves, is given by the decrease in temperature of the water as
q = mass H2O x specific heat H2O x (Tfinal-Tinitial)
That q is for 0.75g which is 0.75g/molar mass KCl = mols KCl.
Then q/mol KCl = gives you J/mol and change that to kJ/mol. Post your work if you get stuck.

Answer 2

4.456 kJ/mo

Answer 3

17.449kJ/mol