Enthalpy of formation of C2H4,CO2 and H2O are 52,−394 and −286‌kJ∕mol respectively. (Given) The reaction is C2H4+3O2→2CO2+2H2O change in enthalpy, (∆H)‌=∆H‌products ‌−∆H‌reactants ‌ ‌=2×(−394)+2×(−286)−(52+0) ‌=−1412‌kJ∕mol