Since we have an insulated experiment, we can assume qsys (heat flow into/out of the solution) is zero. We can treat the system as being composed of the solution (made by mixing the salt and water) + the cup + any heat that left or entered the reaction (i.e. qqoln + qcup + qran). Since qys-0, go ahead and solve for qen and then AH. AH is the change in the amount of heat per mole of salt dissolved, i.e. the ratio of qm/moles 9rxn= JAHon kJ/mol