Enthalpy Change Rechner — Formel

Enthalpy Change of Reaction

Formula

ΔH°rxn = Σ ΔHf°(products) − Σ ΔHf°(reactants)

Where:

  • ΔH°rxn = standard enthalpy of reaction
  • ΔHf° = standard enthalpy of formation

    • Negative ΔH means exothermic (releases heat). Positive ΔH means endothermic (absorbs heat).

    Lösungsbeispiel

    Combustion of methane: products ΔHf° sum = -890 kJ, reactants ΔHf° sum = -75 kJ.

    1. ΔH°rxn = Σ ΔHf°(products) - Σ ΔHf°(reactants)
    2. ΔH°rxn = -890 - (-75)
    3. ΔH°rxn = -890 + 75
    4. ΔH°rxn = -815 kJ (exothermic)