24.2.10—Gibbs free energy and cell potential
- Syllabus
- 9701–2028–2029
- Objective
- 24.2.10
- Level
- A2
Cell potential and Gibbs energy are linked by ΔG° = −nFE°cell
For an electrochemical cell, ΔG° = −nFE°cell, where n is electrons transferred and F is the Faraday constant. A positive E°cell therefore corresponds to negative ΔG°.
Use consistent units and the cell direction. The relation describes thermodynamic driving force under standard conditions, not reaction speed.
If n=2 and E°cell=1.10 V, ΔG°≈−2×96500×1.10 J mol⁻¹≈−212 kJ mol⁻¹.
Do not omit n or treat a negative E°cell as a spontaneous forward cell reaction.
ConceptA-Level CAIE Chemistry A2