A gaseous reaction occurs at a constant pressure of 35.4 bar and releases 62.6 kJ of heat. Before the reaction, the volume of the system was 6.80 L . After the reaction, the volume of the system was 2.60 L . Calculate the total internal energy change, ΔU , in kilojoules. Recall, for this question, ΔU and ΔE are equal.