Enthalpy of Combustion
| Formula / Notation | CₓHᵧOz + O₂ → CO₂ + H₂O; ΔH°comb < 0 (exothermic) |
|---|---|
| Also Known As | Heat of combustion, ΔH°_comb, standard enthalpy of combustion, calorific value |
What is Enthalpy of Combustion?
The heat released when one mole of a substance undergoes complete combustion in excess oxygen under standard conditions. Always negative (exothermic). Used to compare energy content of fuels and in thermochemical calculations using Hess's law.
Formula & Notation
Other Names / Synonyms: Heat of combustion, ΔH°_comb, standard enthalpy of combustion, calorific value
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The heat released when one mole of a substance undergoes complete combustion in excess oxygen under standard conditions. Always negative (exothermic). Used to compare energy content of fuels and in thermochemical calculations using Hess's law.
Enthalpies of combustion are used to calculate heats of formation (via Hess's law), to determine calorific values of fuels (natural gas: −890 kJ/mol; octane: −5471 kJ/mol), to compare biofuel energy densities, and in food science (nutritional caloric content).
Combustion experiments require complete burning in controlled oxygen supplies (bomb calorimeter). Handling of high-energy fuels (hydrogen, acetylene) and volatile organic compounds near ignition sources is extremely hazardous. Always use bomb calorimeters within manufacturer's loading limits.
The formula or notation for Enthalpy of Combustion is: CₓHᵧOz + O₂ → CO₂ + H₂O; ΔH°comb < 0 (exothermic)