Nernst Equation Calculator (Cell Potential)
Enter the standard potential, electrons and reaction quotient to get the cell potential.
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Nernst Equation Calculator (Cell Potential) by TheCalcTools
How the Nernst Equation Calculator (Cell Potential) works
The Nernst equation corrects the standard potential for concentrations (through the reaction quotient Q) and temperature. At 25 °C the factor 2.303RT/F is about 0.05916 V.
For the Daniell cell (zinc and copper, E° = 1.10 V, n = 2), lowering the Cu²⁺ concentration relative to Zn²⁺ raises Q and lowers the cell voltage.
The formula
Worked example
Using the default values shown in the calculator:
| Standard potential E° (V) | 1.1 |
|---|---|
| Electrons transferred n | 2 |
| Reaction quotient Q | 0.01 |
| Temperature (°C) | 25 |
- E = 1.10 − (8.314 × 298.15 ÷ (2 × 96485)) × ln 0.01 = 1.1592 V.
Result:
| Cell potential E (V) | 1.1592 |
|---|---|
| ΔG (kJ/mol) | -223.68 |
| Slope RT/nF × ln 10 (V per decade) | 0.0296 |
Frequently asked questions
What happens when E = 0?
The cell is at equilibrium: Q equals K and no net current flows (a flat battery).
Sources and further reading
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