Electrochemical Cell EMF Calculator

Calculate cell EMF using the Nernst equation and standard electrode potentials.

Enter the half-cell potentials, electron count, and concentrations to compute the cell's EMF under any conditions.

Examples

See how to use the calculator for real-world electrochemical cells.

Daniell Cell (Zn/Cu) at Standard Conditions

basic

Classic Daniell cell with 1M Zn2+ and Cu2+ at 25°C.

Cathode E° (V): 0.34 V

Anode E° (V): -0.76 V

n: 2

Products [C]: 1.0 mol/L

Reactants [C]: 1.0 mol/L

Products Coeff.: 1

Reactants Coeff.: 1

Temp (K): 298 K

Daniell Cell with Non-Standard Concentrations

concentration

Cu2+ = 0.01M, Zn2+ = 1.0M, 25°C.

Cathode E° (V): 0.34 V

Anode E° (V): -0.76 V

n: 2

Products [C]: 0.01 mol/L

Reactants [C]: 1.0 mol/L

Products Coeff.: 1

Reactants Coeff.: 1

Temp (K): 298 K

Cell with Elevated Temperature

temperature

Standard cell, but at 350 K.

Cathode E° (V): 0.80 V

Anode E° (V): 0.00 V

n: 1

Products [C]: 1.0 mol/L

Reactants [C]: 1.0 mol/L

Products Coeff.: 1

Reactants Coeff.: 1

Temp (K): 350 K

Complex Redox Cell (Fe3+/Fe2+ & Ce4+/Ce3+)

complex

Fe3+ + e- ⇌ Fe2+, Ce4+ + e- ⇌ Ce3+, all 0.1M, 25°C.

Cathode E° (V): 1.61 V

Anode E° (V): 0.77 V

n: 1

Products [C]: 0.1,0.1 mol/L

Reactants [C]: 0.1,0.1 mol/L

Products Coeff.: 1,1

Reactants Coeff.: 1,1

Temp (K): 298 K

Other Titles
Understanding Electrochemical Cell EMF: A Comprehensive Guide
Master the Nernst equation, cell potential, and real-world applications.

What is Electrochemical Cell EMF?

  • Definition and Importance
  • Standard vs. Non-Standard Conditions
  • Role in Redox Reactions
Electrochemical cell EMF (Electromotive Force) is the maximum potential difference between two electrodes of a cell when no current is flowing. It determines the cell's ability to drive an electric current through an external circuit.
Standard Cell Potential (E°cell)
Standard cell potential is measured under standard conditions (1M, 1 atm, 25°C) and is calculated from the standard reduction potentials of the cathode and anode.

Common Electrochemical Cells

  • Daniell cell: Zn(s) | Zn2+(1M) || Cu2+(1M) | Cu(s)
  • Lead-acid battery cell

Step-by-Step Guide to Using the Calculator

  • Inputting Potentials and Concentrations
  • Setting Electron Count and Temperature
  • Interpreting Results
How to Enter Data
Begin by entering the standard reduction potentials for the cathode and anode. Specify the number of electrons transferred, and input the concentrations and coefficients for all products and reactants.
Calculating EMF
The calculator uses the Nernst equation to compute the cell EMF, accounting for non-standard concentrations and temperature if provided.

Step-by-Step Examples

  • Input: E°(Cu2+/Cu) = 0.34 V, E°(Zn2+/Zn) = -0.76 V, n = 2, all concentrations 1M, T = 298K
  • Input: E°(Fe3+/Fe2+) = 0.77 V, E°(Ce4+/Ce3+) = 1.61 V, n = 1, all concentrations 0.1M

Real-World Applications of Cell EMF Calculations

  • Battery and Fuel Cell Design
  • Corrosion Analysis
  • Industrial Electrolysis
Cell EMF calculations are essential in designing batteries, fuel cells, and understanding corrosion processes. They help predict cell voltage under various conditions and optimize performance.
Predicting Battery Performance
By adjusting concentrations and temperature, you can estimate how a battery will perform in real-world scenarios.

Industrial & Research Uses

  • Lithium-ion battery voltage prediction
  • Corrosion rate estimation

Common Misconceptions and Correct Methods

  • Misinterpreting Standard Potentials
  • Ignoring Concentration Effects
  • Temperature Dependence
Avoiding Calculation Errors
Always use reduction potentials (not oxidation) and ensure all concentrations and coefficients are correctly matched. Remember, temperature can significantly affect EMF.
Best Practices
Double-check all input values and units. Use the calculator to compare standard and non-standard conditions for deeper understanding.

Mistakes to Avoid

  • Confusing anode/cathode roles
  • Forgetting to convert °C to K

Mathematical Derivation and Examples

  • Nernst Equation Explained
  • Calculating Q (Reaction Quotient)
  • Worked Example Calculations
Nernst Equation
Ecell = E°cell - (0.0592/n) log(Q) at 25°C, or Ecell = E°cell - (RT/nF) ln(Q) for any T. Q is calculated from concentrations and coefficients.
Sample Calculation
For a Daniell cell with [Cu2+] = 0.01M, [Zn2+] = 1.0M, n = 2: Q = [Cu2+]/[Zn2+] = 0.01/1.0 = 0.01. Ecell = 1.10 - (0.0592/2) * log(0.01) = 1.16 V.

Mathematical Examples

  • Daniell cell with non-standard concentrations
  • Temperature effect on EMF