Heat of combustion
The heat of combustion is the enthalpy change when one mole of a substance reacts completely with oxygen under standard conditions. It's calculated using Hess's Law:
ΔH°comb = Σ ΔH°f (products) − Σ ΔH°f (reactants)
Example: Combustion of methane (CH₄ → CO₂ + H₂O): ΔH°comb = [−393.5 + 2(−241.8)] − [−74.8 + 0] = −802.3 kJ/mol