In a constant volume calorimeter 5g of a gas with molecular weight 40 was burnt in excess of oxygen at 298K. The temperature of the calorimeter was found to increase from 298K to 298.75K due to combustion process. Given that the heat capacity of the calorimeter is 2.5kJK-1 , the numerical value for the change in internal energy of combustion of the gas in kJ /mol is?