Enthalpy change
Enthalpy change
Formula
ΔH = H(products) − H(reactants)
Real World
When natural gas (methane) burns in a boiler, the combustion reaction releases approximately −890 kJ mol⁻¹ — an exothermic ΔH that heats homes across the UK every winter.
Exam Focus
Always include a sign and units (kJ mol⁻¹) with every ΔH value; missing the negative sign on an exothermic reaction loses the mark.
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