Chemistry
Heat of Combustion Calculator
Find the enthalpy released by a fuel from formation enthalpies, per mole and per gram.
Your inputs
Change any value to update the result instantly.
Enthalpy of combustion
-2,115.3 kJ/mol
Energy per gram
-47.966 kJ/g
Energy from your sample
-479.66 kJ
Moles in the sample
0.2268 mol
Reading
Exothermic — heat is released, as expected for a fuel
Enter totals already multiplied by their coefficients. Whether the water leaves as liquid or vapour changes the answer — that is the difference between higher and lower heating value.
What this calculator does
Calculates the enthalpy of combustion from formation enthalpies, per mole and per gram of fuel.
What your result means
A negative value means heat is released, which is what you expect from a fuel.
Formula and working
ΔH_comb = ΣνΔH_f°(products) − ΣνΔH_f°(reactants)
- 1
Collect the inputs
Σ ΔH_f° products = -2,220 kJ; Σ ΔH_f° reactants = -104.7 kJ; Molar mass of the fuel = 44.1 g/mol; Sample burned = 10 g
- 2
Apply the formula
ΔH_comb = ΣνΔH_f°(products) − ΣνΔH_f°(reactants)
- 3
Result
Enthalpy of combustion = -2,115.3 kJ/mol
Frequently asked questions
Symbols and assumptions
- ΔH_comb
- Enthalpy of combustion
- ΔH_f°
- Standard enthalpy of formation
- ν
- Stoichiometric coefficient
- • Formation enthalpies are standard values already multiplied by their coefficients.
- • Complete combustion.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • Whether the product water is liquid or vapour changes the answer — that is the higher versus lower heating value distinction.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
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