Free Enthalpy Change Calculator
Calculate the enthalpy change of a reaction from the sum of enthalpies of formation of products minus reactants.
kJ
kJ
Enthalpy Change (ΔH°)
-815.0 kJ
Enthalpy Change (ΔH°) vs Sum of ΔHf° (Products)
Enthalpy Change of Reaction
Formula
ΔH°rxn = Σ ΔHf°(products) − Σ ΔHf°(reactants)
Where:
Negative ΔH means exothermic (releases heat). Positive ΔH means endothermic (absorbs heat).
Example Calculation
Combustion of methane: products ΔHf° sum = -890 kJ, reactants ΔHf° sum = -75 kJ.
- 01ΔH°rxn = Σ ΔHf°(products) - Σ ΔHf°(reactants)
- 02ΔH°rxn = -890 - (-75)
- 03ΔH°rxn = -890 + 75
- 04ΔH°rxn = -815 kJ (exothermic)
Frequently Asked Questions
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