When a 0.245 sample of benzoic acid is combusted in a bomb calorimeter, the temperature rises 1.644. When a 0.265 sample of caffeine, C8H10O2N4 , is burned, the temperature rises 1.465. Using the value 26.38 for the heat of combustion of benzoic acid, calculate the heat of combustion per mole of caffeine at constant volume.