Combustion Reaction Calculator to Balance Hydroc...

What is a Combustion Reaction?

Combustion is a rapid, exothermic chemical reaction between a fuel and an oxidizer (usually oxygen) that produces heat and light. Complete combustion of a hydrocarbon produces carbon dioxide (CO₂) and water (H₂O). Incomplete combustion produces CO, soot, and other pollutants.

🔥 Combustion Calculator

Use our free calculator for instant, accurate results.

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📐 Formula

CₙH_m + (n + m/4)O₂ → nCO₂ + (m/2)H₂O

General formula for complete combustion of hydrocarbon CₙHₘ. Multiply through by 2 to eliminate fractions in coefficients.

📝 Worked Example

Methane (CH₄): n=1, m=4
CH₄ + (1 + 4/4)O₂ → 1CO₂ + 2H₂O
CH₄ + 2O₂ → CO₂ + 2H₂O
ΔH = −890 kJ/mol (heat released)

📝 How to Use the Calculator

Enter Fuel FormulaType the hydrocarbon (e.g., C₃H₈ for propane, C₈H₁₈ for octane).

Select Combustion TypeComplete (O₂ excess) or incomplete (limited O₂).

Balance EquationView the balanced chemical equation with correct stoichiometric coefficients.

Calculate HeatSee the enthalpy of combustion and heat released per gram of fuel.

❓ FAQ

Why does incomplete combustion produce CO instead of CO₂?

When O₂ is limited, there is not enough oxygen to fully oxidize carbon to CO₂. The intermediate product CO (carbon monoxide) forms instead.

What is the calorific value of a fuel?

It is the heat energy released per unit mass during complete combustion. For methane: ~55 MJ/kg; for octane (petrol): ~47 MJ/kg.