⚡

Nernst Equation

Electrochemical cell potential — E = E° − (RT/nF) · ln Q

Electrochemistry Physical Chemistry Galvanic Cell Thermodynamics

Preset:

[Ox] (anode): 1.000 M [Red] (cathode): 1.000 M

Temperature T: 298 K (25 °C) Electrons n: 2

Graph:

E° = +1.100 V Q = 1.000 ln Q = 0.000 E = +1.100 V ΔG = −212.5 kJ/mol

⚡ Nernst Equation

The Nernst equation relates the electrochemical cell potential E to its standard potential E° and the reaction quotient Q:

E = E° − (RT / nF) · ln Q

At 25 °C (298 K) this simplifies to: E = E° − (0.02570 / n) · ln Q = E° − (0.05916 / n) · log₁₀ Q

E° — standard reduction potential (both half-cells at 1 M, 25 °C, 1 atm) · R = 8.314 J mol⁻¹ K⁻¹ · F = 96485 C mol⁻¹ · n — electrons transferred · Q = [products] / [reactants].

When Q = 1 (standard conditions), ln Q = 0 and E = E°. As reactant concentration increases, Q decreases, raising E above E°. The cell reaches equilibrium when E = 0 and Q = K_eq. The cell voltage also drives ΔG = −nFE.