The enthalpy of combustion of propane (C3H8) gas in terms of given data is : Bond energy (kJ/mol).

εC−H εO=O εC−=O εO−H εC−C
+x1 +x2 +x3 +x4 +x5

Resonance energy of CO₂ is − z kJ/mol and Δ Hvaporization [H₂O (l)] is y(kJ/mol).