Combustion reactions involve reacting a substance with oxygen. When compounds containing carbon and hydrogen are combusted, carbon dioxide and water are the products. Using the enthalpies of combustion for C4H4 (-2341 kJ/mole), C4H8 (-2755 kJ/mole), and H2 (-286 kJ/mole), calculate H for the reaction: C4H4(g) + 2H2(g) ? C4H8(g)