Calculating K from ΔG°

Calculating an equilibrium constant from a standard free energy change means substituting ΔG°, converted to joules, and the absolute temperature into ΔG° = −RT ln K, isolating ln K, and solving for K by exponentiating both sides.

For a reaction with ΔG° = −29.0 kJ/mol at 298 K, first converted to −29,000 J/mol, ln K = −ΔG°/RT = 29,000/(8.314 × 298) ≈ 11.7, so K = e¹¹·⁷ ≈ 1.2 × 10⁵, a large constant consistent with the strongly negative ΔG° and, by Chem 2130, an equilibrium mixture favoring products heavily.