Faraday Electrolysis Calculator
The Faraday electrolysis calculator computes the mass of substance deposited or dissolved during electrolysis from the applied current, time, molar mass, and number of electrons per ion. Michael Faraday formulated his laws of electrolysis in 1833, establishing the quantitative relationship between electric charge and chemical change. These laws underpin the design of industrial electrochemical processes from aluminum smelting to copper refining to hydrogen electrolyzers. Enter the current, time, molar mass, and n-factor for the ion being deposited to find the mass in grams and moles deposited.
Faraday's laws formulas
Charge: Q = I * t (coulombs)
Moles of electrons: n_e = Q / F
Moles deposited: n_mol = n_e / n (n = ions per electron transfer)
Mass deposited: m = n_mol * M (g)
F = 96,485 C/mol
Common electrolysis examples
- Cu2+ + 2e- to Cu: n = 2, M = 63.55 g/mol
- Ag+ + e- to Ag: n = 1, M = 107.87 g/mol
- Al3+ + 3e- to Al: n = 3, M = 26.98 g/mol
- 2H+ + 2e- to H2: n = 2, M = 2.016 g/mol
- Ni2+ + 2e- to Ni: n = 2, M = 58.69 g/mol
Faraday electrolysis: frequently asked questions
What are Faraday's laws of electrolysis?
First law: the mass deposited (m) is directly proportional to the charge passed: m = (Q/F) * (M/n), where Q = charge in coulombs, F = 96,485 C/mol, M = molar mass, n = electrons per ion. Second law: for the same charge passed, masses of different substances deposited are proportional to their equivalent weights (M/n). Both laws follow from conservation of charge and stoichiometry.
How do I calculate the mass deposited in electrolysis?
m = (I * t * M) / (n * F), where I = current in amperes, t = time in seconds, M = molar mass in g/mol, n = number of electrons transferred per ion, F = 96,485 C/mol. For example, to deposit copper (M = 63.55, n = 2) at 2.0 A for 3600 s: m = (2.0 * 3600 * 63.55) / (2 * 96485) = 2.37 g.
What is current efficiency?
Current efficiency (also Faradaic efficiency) is the fraction of the total charge that goes toward the desired electrode reaction. It is less than 100% when side reactions occur (e.g., hydrogen or oxygen evolution competing with metal deposition). Current efficiency = (actual mass deposited) / (theoretical mass from Faraday's law) * 100%.
What is the Faraday constant?
F = 96,485 C/mol, the charge of one mole of electrons. It equals the Avogadro constant times the elementary charge: F = NA * e = 6.022e23 mol-1 * 1.602e-19 C = 96,485 C/mol. One coulomb passes when a current of one ampere flows for one second. Thus the charge Q = I (A) * t (s).
What are practical applications of electrolysis?
Electrolysis is used for: (1) electroplating metals (chrome, gold, nickel) onto surfaces for corrosion protection or decoration; (2) electrorefining copper and aluminum production (Hall-Heroult process); (3) water electrolysis to produce hydrogen fuel; (4) chlor-alkali process (NaCl to Cl2 and NaOH); (5) anodizing aluminum; (6) electrochemical machining.
Official sources
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.