Standard Electrode Potential Calculator

The Standard Electrode Potential Calculator applies the Nernst equation to find the actual cell potential of an electrochemical half-reaction under non-standard conditions — useful in chemistry, battery design, and corrosion analysis. Enter your Standard Electrode Potential (E°), temperature, number of electrons transferred (n), and Reaction Quotient (Q), then select your reference electrode to get the Cell Potential (E). Secondary outputs include the Nernst term and the reference electrode correction voltage.

V

Standard reduction potential at 25°C and 1M concentration

K

Temperature in Kelvin

Number of electrons involved in the half-reaction

Ratio of product to reactant activities/concentrations

Results

Cell Potential (E)

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Nernst Term (RT/nF × ln(Q))

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Temperature

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Reference Electrode Correction

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Frequently Asked Questions

What is standard electrode potential?

Standard electrode potential (E°) is the voltage of an electrochemical cell when all components are at standard conditions (25°C, 1 atm pressure, 1M concentration). It measures the tendency of a species to be reduced.

What is the Nernst equation and how does it work?

The Nernst equation calculates the electrode potential under non-standard conditions: E = E° - (RT/nF) × ln(Q). It accounts for temperature and concentration effects on cell potential.

How do I determine the reaction quotient (Q)?

The reaction quotient Q is the ratio of product activities to reactant activities. For aA + ne⁻ → bB, Q = [B]ᵇ/[A]ᵃ. Use concentrations for dilute solutions and activities for precise calculations.

Why does temperature affect electrode potential?

Temperature affects the kinetic energy of ions and the equilibrium position of redox reactions. Higher temperatures generally decrease cell potential due to the RT term in the Nernst equation.

What's the difference between NHE and SHE reference electrodes?

NHE (Normal Hydrogen Electrode) and SHE (Standard Hydrogen Electrode) are both hydrogen-based references set at 0.000 V. SHE is the modern standard, while NHE is the older designation.

How many electrons should I use for the calculation?

Use the number of electrons transferred in the balanced half-reaction. For example, Cu²⁺ + 2e⁻ → Cu uses n = 2, while Fe³⁺ + e⁻ → Fe²⁺ uses n = 1.

Can electrode potential be negative?

Yes, electrode potentials can be negative. Negative values indicate that the half-reaction is less favorable than the hydrogen reference. Many metals like zinc have negative standard potentials.