How is ΔG related to cell potential?

ΔG = −nFE. A 1.1 V two-electron cell has a ΔG of about −212 kJ/mol and an equilibrium constant around 10³⁷.

Nernst Equation Calculator

Cell potential away from standard conditions, plus ΔG and K.

Cell potential away from standard conditions, plus ΔG and K. E = E° − (RT/nF)·ln Q.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Standard cell potential (E°)

Electrons transferred

Reaction quotient (Q)

Temperature

°C

Cell potential E (V)

1.1

ΔG -212.27 kJ/mol · K 1.5406e+37

Cell potential1.1 V

Standard potential1.1 V

Nernst correction0 V

ΔG-212.268 kJ/mol

Equilibrium constant1.5406e+37

E = E° − (RT/nF)·ln Q. At Q = 1 the correction vanishes and the cell sits at its standard potential; as products build the potential falls, reaching zero exactly at equilibrium — which is what a flat battery is. The equilibrium constant follows from E° alone and is enormous for any usable cell: a 1.1 V two-electron cell has K around 10³⁷, which is why the reaction runs essentially to completion.

How the Nernst Equation Calculator works

E = E° − (RT/nF)·ln Q. As products build, the potential falls, reaching zero exactly at equilibrium — which is what a flat battery is. The equilibrium constant follows from E° alone and is enormous for any usable cell.

Also known as: cell potential calculator · electrochemical cell calculator · emf calculator · nernst equation formula

Where to go next

The Nernst Equation question rarely arrives on its own. These are the ones that usually come with it:

Electrolysis Calculator — Faraday's law: mass deposited from charge passed.
Gibbs Free Energy Calculator — ΔG = ΔH − TΔS, with the unit mismatch handled.
Equilibrium Constant Calculator — Kp from Kc, with Δn counting gases only.
Speed Distance Time Calculator — Any one of the three from the other two, in four units.

Sources

Frequently asked questions

What is the Nernst equation?

E = E° − (RT/nF)·ln Q, giving the cell potential at non-standard concentrations. At Q = 1 the correction vanishes and E equals E°.

What happens at equilibrium?

E reaches zero. A battery is flat not because it has run out of chemicals but because the reaction quotient has reached the equilibrium constant.

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