For each hydrocarbon below, write the balanced combustion equation, use the standard enthalpies of formation provided (kJ mol−1) to calculate the enthalpy change per mole of fuel at 298 K, and then rank the fuels from most exothermic to least exothermic per mole.
Data: C2H2(g) = +227, C2H4(g) = +52, C2H6(g) = –85, CO2(g) = –394, H2O(l) = –286, O2(g) = 0.