Pick a mode and solve it.
Switch between the Nernst equation, standard cell potential, and Faraday's law of electrolysis. Every result comes with the full step-by-step working shown below it.
The number of electrons in the balanced overall redox equation.
Q = [products]/[reactants], each raised to its stoichiometric coefficient.
Defaults to 25 °C (298.15 K), the usual assumption unless a problem states otherwise.
Pick the half-reaction that gets oxidized — this tool reverses it and subtracts its reduction potential automatically.
Leave blank to auto-balance from the two half-reactions using the lowest common multiple of electrons.
n is the number of electrons in the half-reaction — 1 for Ag⁺ + e⁻ → Ag, 2 for Cu²⁺ + 2e⁻ → Cu, 3 for Al³⁺ + 3e⁻ → Al, and so on.
+ View the full standard reduction potential table (25 °C)
| Half-reaction (reduction) | E° (V) |
|---|
Get an answer in three moves.
Each mode is self-contained — pick it, fill it in, read the working.
Choose your mode
Nernst equation for non-standard concentrations, cell potential for a fresh galvanic cell, or Faraday's law for electrolysis and electroplating problems.
Fill in what you know
For cell potential, just pick two half-reactions from the dropdown — the built-in table and electron balancing handle the rest.
Open detailed options
Need a non-25 °C temperature, your own reduction potentials, or a different time unit? Expand "Detailed options" in any mode.
Read the full working
Every calculation shows each intermediate step — no black box — so you can check it against your own working line by line.
What's running under the hood.
Three relationships cover almost every electrochemistry problem you'll meet.
Nernst equation
Adjusts the standard cell potential for real, non-1 M concentrations. At 25 °C this simplifies to E = E° − (0.0592/n) log₁₀Q.
Standard cell potential
Both values come from a standard reduction potential table. The higher (more positive) potential is always the cathode — the site of reduction.
Faraday's law
Links current, time and molar mass through the Faraday constant, F = 96,485 C/mol, and the number of electrons transferred per ion, n.
Questions people actually ask.
The short answers — with the long ones one tap away.
What is the Nernst equation used for?+
The Nernst equation calculates the actual cell potential of an electrochemical cell when concentrations are not at standard 1 M conditions. It adjusts the standard cell potential, E°cell, using temperature, the number of electrons transferred, and the reaction quotient Q.
How do I find the standard cell potential, E°cell?+
Subtract the standard reduction potential of the anode (oxidation) half-reaction from the standard reduction potential of the cathode (reduction) half-reaction: E°cell = E°cathode − E°anode. Pick both half-reactions from a standard reduction potential table.
How do you know if a cell reaction is spontaneous?+
A cell reaction is spontaneous under the given conditions when its cell potential, Ecell, is positive, which also means Gibbs free energy, ΔG, is negative. A negative Ecell means the reverse reaction is spontaneous instead.
What is Faraday's law of electrolysis?+
Faraday's law relates the amount of substance produced or consumed at an electrode to the electric charge passed through the cell. The moles of electrons transferred equal current multiplied by time, divided by the Faraday constant, 96,485 C/mol.
How do I calculate the mass deposited during electroplating?+
Multiply the current by the time in seconds to get total charge, divide by the Faraday constant and the number of electrons in the half-reaction to get moles of metal, then multiply by the molar mass. The Faraday's law mode above does all of these steps automatically.
What does a negative standard reduction potential mean?+
A negative standard reduction potential means that species is a weaker oxidizing agent than hydrogen and is more likely to be oxidized than reduced compared to the hydrogen reference electrode. Active metals like lithium and sodium have strongly negative values.
Is this tool free, and where does my data go?+
It's completely free and runs entirely in your browser — nothing you enter or calculate is uploaded, logged, or sent to any server. No account, no sign-up, no limits.