The standard enthalpy of reaction, DH°rxn for C2H2(g) + 2 H2(g) ® C2H6(g) is -311.5 kJ mol-1. Determine the value of DE°rxn for this reaction. Q 2 options: 1) -306.5 kJ mol-1 2) -309.0 kJ mol-1 3) -314.0 kJ mol-1 4) -316.46 kJ mol-1 5) +4646 kJ mol-1