Cell Potential Calculator
Works out the voltage of a cell under standard conditions.
Standard cell potential E°
— V
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Standard ΔG — kJ/mol
Equilibrium constant K —
As written, the cell is —
Reading this —
The formula
E°cell = E°cathode − E°anode ΔG° = −nFE° K = e^(nFE° ÷ RT)
Both electrode values are reduction potentials from the same table, which is why one is subtracted.
What to watch out for
The default values are the zinc–copper cell. For non-standard concentrations, take the result to the Nernst equation calculator.
Frequently Asked Questions
What is the standard potential of a zinc–copper cell?
0.34 − (−0.76) = 1.10 V.
What does a negative cell potential mean?
The reaction as written is not spontaneous. It runs the other way unless a voltage is applied.