Redox Reaction Calculator
Balance electron transfer in a redox reaction and calculate the cell potential.
About Redox Reaction Calculator
A positive cell potential means a spontaneous reaction, and the free energy change scales with both potential and electron count. Electron numbers must be equalised between half-reactions before combining, though this does not change the potential. Cell potential is intensive and does not depend on how the equation is scaled, whereas free energy does — a distinction that catches out many students.
Formula
Redox Reaction
E°cell = E°oxidation + E°reduction; ΔG° = −nFE°cell
- n
- Electrons transferred per reaction
- F
- Faraday constant, 96,485 C/mol
Worked example
With the default values below, Redox Reaction Calculator returns Standard Cell Potential of 1.1000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Standard potential of the oxidation half-reactionaccepts -5–5 V
- 0.76 V
- Standard potential of the reduction half-reactionaccepts -5–5 V
- 0.34 V
- Electrons in the oxidation half-reactionaccepts 1–10
- 2
- Electrons in the reduction half-reactionaccepts 1–10
- 2
Results
- Standard Cell Potential
- 1.1000 V
- Electrons Transferred
- 2
- Standard Gibbs Free Energy Change
- -212.267 kJ/mol
- Equilibrium Constant
- 15,401,729,310,692,788,000,000,000,000,000,000,000.0000
- Spontaneity
- Spontaneous as written
Step by step
- 1Values used
- 2Redox Reaction
- 3Standard Cell Potential= 1.1000 V
- 4Electrons Transferred= 2
- 5Standard Gibbs Free Energy Change= -212.267 kJ/mol
- 6Equilibrium Constant= 15,401,729,310,692,788,000,000,000,000,000,000,000.0000
- 7Spontaneity= Spontaneous as written
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
How is Redox Reaction calculated?
E°cell = E°oxidation + E°reduction; ΔG° = −nFE°cell A positive cell potential means a spontaneous reaction, and the free energy change scales with both potential and electron count. Electron numbers must be equalised between half-reactions before combining, though this does not change the potential.
Why does Redox Reaction matter?
Cell potential is intensive and does not depend on how the equation is scaled, whereas free energy does — a distinction that catches out many students.
What values do I need to enter?
This calculator takes 4 inputs: Standard potential of the oxidation half-reaction, Standard potential of the reduction half-reaction, Electrons in the oxidation half-reaction, Electrons in the reduction half-reaction. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.