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Galvanic Cell EMF Calculator

Work out galvanic cell emf instantly with clear inputs, formula shown and shareable results.

About Galvanic Cell EMF Calculator

Away from standard conditions a cell's voltage follows the Nernst equation, E = E0 - (RT/nF) ln Q. Diluting the products relative to the reactants pushes Q below one and raises the voltage. At 25 C the RT/nF factor is 0.02569/n volts, so a two-electron cell with Q = 0.01 gains about 59 mV over its standard potential.

Formulas

Nernst equation

E = E0 - (RT / nF) x ln Q

Room-temperature form

E = E0 - (0.0592 / n) x log10 Q

Worked example

With the default values below, Galvanic Cell EMF Calculator returns Cell EMF Under These Conditions of 1.1592. Change any input above and every figure here is recalculated in your browser.

Inputs used

Standard cell potential E0
1.1 V
Electrons transferred (n)minimum 1
2
Reaction quotient Qminimum 0
0.01
Temperature
25 C

Results

Cell EMF Under These Conditions
1.1592 V
Nernst Correction
0.0592 V
log10(Q)
-2.0000
Free Energy Change
-223.68 kJ/mol

Step by step

  1. 1Values used
  2. 2Nernst equation
  3. 3Room-temperature form
  4. 4Cell EMF Under These Conditions= 1.1592 V
  5. 5Nernst Correction= 0.0592 V
  6. 6log10(Q)= -2.0000
  7. 7Free Energy Change= -223.68 kJ/mol

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What happens as the cell discharges?

Products build up, Q rises towards K, and the voltage falls. At Q = K the emf is zero and the battery is flat.

Why does temperature appear?

The RT/nF slope grows with temperature, so concentration effects on voltage are larger in a hot cell than a cold one.

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