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Thermochemistry & Thermodynamics

Standard Enthalpy of Combustion

The enthalpy change when one mole of a substance burns completely in excess oxygen under standard conditions.

Formula / equation ΔH_c°
Unit kJ/mol

In depth

Combustion enthalpies are always negative and are measured very accurately in a bomb calorimeter, which is why they are often used with Hess's law to obtain formation enthalpies that cannot be measured directly. They also give the energy content of fuels and foods.

Examples in the real world

Methane releases 890 kJ/mol, ethanol 1367 kJ/mol, and glucose 2803 kJ/mol.