The Nernst equation
The Nernst equation calculates the reduction potential of a half-cell at non-standard conditions. It accounts for temperature and the reaction quotient Q:
E = E° − (RT / nF) × ln(Q)
At 25°C: E = E° − (0.05916 / n) × log(Q)
Where E° is the standard electrode potential, n = electrons transferred, R = 8.314 J/mol·K, F = 96,485 C/mol.
Standard reduction potentials (examples)
- F₂ + 2e⁻ → 2F⁻: E° = +2.87 V (strongest oxidizer)
- Cu²⁺ + 2e⁻ → Cu: E° = +0.34 V
- 2H⁺ + 2e⁻ → H₂: E° = 0.00 V (reference)
- Zn²⁺ + 2e⁻ → Zn: E° = −0.76 V
- Li⁺ + e⁻ → Li: E° = −3.05 V (strongest reducer)