Cell Potential Calculator Formula

Understand the math behind the cell potential calculator. Each variable explained with a worked example.

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Formulas Used

Standard Cell Potential (E°cell)

e_cell = e_cathode - e_anode

Variables

VariableDescriptionDefault
e_cathodeE° of Cathode (Reduction)(V)0.34
e_anodeE° of Anode (Reduction)(V)-0.76

How It Works

Standard Cell Potential

Formula

E°cell = E°cathode − E°anode

Where:

  • E°cell = standard cell potential (V)
  • E°cathode = standard reduction potential of the cathode
  • E°anode = standard reduction potential of the anode

    • Both values are entered as standard reduction potentials. The anode undergoes oxidation, so its reduction potential is subtracted.

    Positive E°cell means the reaction is spontaneous (galvanic cell).

    Worked Example

    A Cu/Zn galvanic cell: Cu²⁺/Cu E° = +0.34 V (cathode), Zn²⁺/Zn E° = -0.76 V (anode).

    e_cathode = 0.34e_anode = -0.76
    1. 01E°cell = E°cathode - E°anode
    2. 02E°cell = 0.34 - (-0.76)
    3. 03E°cell = 0.34 + 0.76
    4. 04E°cell = 1.10 V

    Frequently Asked Questions

    What does a positive E°cell mean?

    A positive E°cell indicates a spontaneous reaction (ΔG° < 0). This is a galvanic (voltaic) cell that can produce electricity.

    How do I identify cathode and anode?

    The half-cell with the higher reduction potential is the cathode (reduction occurs). The lower one is the anode (oxidation occurs).

    How is E°cell related to ΔG°?

    ΔG° = -nFE°cell, where n is moles of electrons transferred and F = 96485 C/mol is Faraday's constant.

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