1. Reacting 50 mL of H2(g) with 50 mL of C2H4(g) produces 50 mL of C2H6(g) at 1.5 atm. If the reaction produces 3.1 x 10^2 J of heat and the decrease in volume requires the surroundings do 7.6 J of work on the gases, what is the change in internal energy of the gases? 2. Change in Internal Energy = Q(heat energy) + W(work) Work = - P x (change in volume) 3. I know how to apply these equations but have no idea about the " 7.6 J of work" part.