substance X has a molar mass of 107.6 g/mol. When 2.50 g of substance x burns in an iron calorimeter, the temp. of the calorimeter and the water (2.000 Kg) increases from 25.8 deg. C to 38.7 deg. C. What is the molar heat of combustion of substance X in KJ/Mole. Heat capacity of calorimeter is 0.555 kJ/deg C.