A calorimeter that contains 2500 g of surrounding water is used to measure the heat associated with the reaction of 520 g of a reactant. Calculate the energy, in joules per kilogram of reactant, associated with the reaction if the temperature of the water changes from 27.40 C to 20.28 C. Assume that the specific heat of water is 4.184 J/kg C. Is the reaction exothermic or endothermic?