An ideal gaseous reaction (which is a hypothetical gaseous reaction that conforms to the laws governing gas behavior) occurs at a constant pressure of 50.0 atm and releases 73.2 kj of heat. before the reaction, the volume of the system was 7.60 l . after the reaction, the volume of the system was 2.00 l . calculate the total internal energy change, δe, in kilojoules. express your answer with the appropriate units.