Free Equilibrium Constant Calculator

Calculate the equilibrium constant (K) from the standard Gibbs free energy change (ΔG°) and temperature using ΔG° = -RT ln(K).

kJ/mol
K

Equilibrium Constant (K)

56.6114

Equilibrium Constant (K) vs Standard ΔG°

Equilibrium Constant from ΔG°

Formula

K = e^(−ΔG° / RT)

Equivalently: ΔG° = −RT ln(K)

Where:

  • K = equilibrium constant
  • ΔG° = standard Gibbs free energy change (J/mol)
  • R = 8.314 J/(mol·K)
  • T = temperature (K)
  • Large K (K >> 1) means products are favored. Small K (K << 1) means reactants are favored.

    Example Calculation

    A reaction with ΔG° = -10 kJ/mol at 298 K.

    1. 01K = e^(-ΔG°/RT)
    2. 02K = e^(-(-10000)/(8.314 × 298))
    3. 03K = e^(10000/2477.6)
    4. 04K = e^(4.036)
    5. 05K = 56.6

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