Free Gibbs Free Energy Calculator

Calculate Gibbs free energy change (ΔG) from enthalpy change (ΔH), entropy change (ΔS), and temperature to determine reaction spontaneity.

kJ
J/K
K

Gibbs Free Energy (ΔG)

-85.10 kJ

Gibbs Free Energy (ΔG) vs Enthalpy Change (ΔH)

Gibbs Free Energy

Formula

ΔG = ΔH − TΔS

Where:

  • ΔG = Gibbs free energy change (kJ)
  • ΔH = enthalpy change (kJ)
  • T = temperature (K)
  • ΔS = entropy change (J/K, converted to kJ/K by dividing by 1000)
  • If ΔG < 0, the reaction is spontaneous. If ΔG > 0, it is non-spontaneous. If ΔG = 0, the system is at equilibrium.

    Example Calculation

    A reaction with ΔH = -100 kJ and ΔS = -50 J/K at 298 K.

    1. 01ΔG = ΔH - TΔS
    2. 02ΔG = -100 - (298 × (-50)/1000)
    3. 03ΔG = -100 - (-14.9)
    4. 04ΔG = -100 + 14.9
    5. 05ΔG = -85.1 kJ (spontaneous)

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