Nernst Equation

A battery is strongest when fresh and fades as it discharges. The Nernst equation shows exactly how cell voltage depends on concentration.

Nernst Equation / Galvanic CellLive

voltage from concentration

Controls

Presets

Standard EMF E° (V)

Electrons transferred n

Reaction quotient Q

Temperature (K)

A battery's voltage depends on concentrations, not just chemistry. The Nernst equation E = E° − (RT/nF)·lnQ shows the cell voltage sliding as reactants are consumed — and reaching zero when the reaction hits equilibrium. Educational tool.

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Data Inspector

Cell voltage E1.100 V

Thermal term RT/nF0.0128 V

Spontaneous?yes (E > 0)

Governing equation

E = E^{\circ} - \frac{R T}{n F} ln Q = 1.1 - \frac{( 8.314 ) ( 298 )}{( 2 ) ( 96485 )} ln (1) = 1.100 V

Reading this result: At Q ≈ 1 the log term nearly vanishes, so the cell sits close to its standard EMF of 1.10 V.

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How it works

The Nernst equation, E = E° − (RT/nF)·lnQ, relates a cell's actual voltage to its standard EMF and the reaction quotient Q. As reactants deplete, Q rises and the voltage falls, reaching zero at equilibrium — the chemistry of a dying battery. Educational tool.

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The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.