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Heat of Reaction (Hess) Calculator

ΔH_rxn from formation enthalpies (2 + 2 species).

Compute the standard enthalpy of reaction ΔH_rxn from the standard formation enthalpies of up to two products and two reactants, weighted by their stoichiometric coefficients.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

kJ/mol
kJ/mol
kJ/mol
kJ/mol

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

ΔH_rxn = Σ n · ΔHf(products) − Σ n · ΔHf(reactants)

In depth

Compute the standard enthalpy of reaction ΔH_rxn from the standard formation enthalpies of up to two products and two reactants, weighted by their stoichiometric coefficients.