How would I calculate the heat of solution in Joules for dissolving 0.1 mole of NH4NO3 in 100 mL of water?

Question

The initial temperature was 22.8 degrees celsius and the temperature after the salt dissolved was 18.1 degrees celsius.

Answer 1

Dissolving NH4NO3 is an endothermic reaction. How much heat is absorbed can be measured by using the temperature of the water.
q = mass H2O x specific heat H2O x (Tfinal-Tinitial).
That is q for 0.1M so
q/0.1 = q in kJ/mol.

Answer 2

Do I have to add q of the caloriemeter to that?

Answer 3

If there is a calorimeter constant you didn't type the entire question and my response will not be right.. You may need to include. Henceforth, please don't edit the question.