In a Finkelstein reaction, 1‑chloropropane is converted to 1‑iodopropane by excess NaI in dry acetone at 298 K. The standard Gibbs free energy change for the reaction is ΔG° = –3.4 kJ mol⁻¹. Calculate the equilibrium constant K at this temperature.

Step-by-step solution

1. Convert ΔG° to joules: ΔG° = –3400 J mol⁻¹.
2. Use the relation ΔG° = –RT ln K, where R = 8.314 J mol⁻¹ K⁻¹ and T = 298 K.
3. Solve for ln K: ln K = –(ΔG°)/(RT) = 3400/(8.314×298) = 1.374.
4. Exponentiate to get K: K = $e^{1.374}$ ≈ 3.95 ≈ 4.0.
5. Thus the equilibrium constant is approximately 4.0.

Concept tested: Equilibrium constant from Gibbs free energy

Published 16 October 2026 · How this solution was prepared and checked