Electrochemistry Calculator
The electrochemistry calculator computes the standard cell potential, Gibbs free energy change, and equilibrium constant for a galvanic cell from the standard reduction potentials of the cathode and anode half-reactions. Electrochemical cells are the basis of all batteries, fuel cells, and electrolytic processes including metal refining, electroplating, and chlor-alkali production. Understanding cell potential allows engineers to design energy storage systems and chemists to predict whether an oxidation-reduction reaction will occur spontaneously. Enter the cathode and anode standard reduction potentials and the number of electrons transferred to obtain the complete thermodynamic picture.
Electrochemistry formulas
E_cell = E_cathode - E_anode
delta_G = -n * F * E_cell (F = 96,485 C/mol)
K = exp(n * F * E_cell / (R * T))
At 25 degC: E_cell = (0.05916 / n) * log10(K)
Spontaneous if E_cell greater than 0 (delta G less than 0)
Standard reduction potential examples
- F2 + 2e- to 2F-: +2.87 V (strongest oxidizer)
- MnO4- + 8H+ + 5e- to Mn2+ + 4H2O: +1.51 V
- Cu2+ + 2e- to Cu: +0.34 V
- 2H+ + 2e- to H2: 0.00 V (SHE reference)
- Zn2+ + 2e- to Zn: -0.76 V
- Li+ + e- to Li: -3.04 V (strongest reducer)
Electrochemistry: frequently asked questions
What is cell potential?
Cell potential (E_cell, also EMF) is the voltage a galvanic (voltaic) cell can produce. It is calculated as: E_cell = E_cathode - E_anode, where E_cathode and E_anode are the standard reduction potentials of the half-reactions (measured relative to the standard hydrogen electrode, SHE, which is defined as 0 V). A positive E_cell means the reaction is spontaneous.
How are cell potential and Gibbs free energy related?
The relationship is: delta G = -n * F * E_cell, where n is the number of moles of electrons transferred and F = 96,485 C/mol (Faraday's constant). A positive E_cell means negative delta G (spontaneous). Standard values: delta G degrees = -n * F * E_cell_standard. This equation connects electrochemistry to thermodynamics directly.
What is the relationship between E_cell and the equilibrium constant?
At standard conditions: E_cell = (R*T / (n*F)) * ln(K), or equivalently: E_cell = (0.02569 V / n) * ln(K) at 25 degC. Rearranging: K = exp(n*F*E_cell / (R*T)). A positive E_cell gives K greater than 1 (products favored). At 25 degC: E_cell = (0.05916 V / n) * log10(K).
What is a standard reduction potential?
Standard reduction potentials are measured relative to the standard hydrogen electrode (SHE = 0.00 V) under standard conditions (1 M concentration, 1 atm, 25 degC). They are listed in electrochemical series tables. The more positive the reduction potential, the stronger the oxidizing agent (more easily reduced). Common values: F2/F- = +2.87 V; O2/H2O = +1.23 V; Cu2+/Cu = +0.34 V; Fe3+/Fe2+ = +0.77 V; Zn2+/Zn = -0.76 V; Li+/Li = -3.04 V.
What is the Faraday constant?
The Faraday constant F = 96,485 C/mol is the charge of one mole of electrons. It equals the Avogadro number times the elementary charge: F = NA * e = 6.022e23 * 1.602e-19 C = 96,485 C/mol. It appears in both the Nernst equation and Faraday's laws of electrolysis. In SI units, 1 coulomb = 1 ampere * 1 second.
Official sources
- NIST: NIST Chemistry WebBook - Standard Reduction Potentials.
- IUPAC: IUPAC Recommendations on Electrochemical Nomenclature.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.