Standard enthalpy of combustion
Standard enthalpy of combustion
Formula
ΔH°c: substance + O₂ → CO₂ + H₂O (always negative)
Real World
The standard enthalpy of combustion of octane (−5471 kJ mol⁻¹) underpins fuel efficiency ratings — Shell uses these values to compare petrol blends for energy output per litre.
Exam Focus
Combustion enthalpy is always negative; if your calculated answer is positive, check you haven't reversed the equation.
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