How do you calculate the heat of solution?

Question

I have 5.0 grams of a salt dissolved in 25.0 mL of water. I have the temperature of the solution.

Trial One:
highest temperature: 24.0 C
lowest temperature: 11.0 C

Trial Two:
highest temperature: 25.0 C
lowest temperature: 13.0 C

Calculate the heat of solution in J/g for each trial and the average heat of solution. (delta H sub s)

Answer 1

Change grams of NaCl to moles of NaCl:
5.0 g / 58.5 g NaCl per mol (Na = 23, Cl = 35.5)

Calculate joules heat using the change in temperature of the water:
Q=mc(Tf-Ti)
Q = (25.0 g) x (4.184) x (24.0oC-11.0oC)

To get J/g just divide above answer by 5 g NaCl

To get delta H sub s:
moles from first answer / second answer (changed from joules to kJ)