When 12.8 g of solid potassium chloride dissolves in 75.0 g of water in a coffee-cup calorimeter, the temperature drops from 31.0 °C to 21.6 °C. Assume the specific heat capacity of solution is the same as that of water. Calculate the heat of solution for potassium chloride in kJ/mol. KCl(s) → K+ (aq) + Cl−(aq)