Faraday's Law of Electrolysis Calculator
Calculate the mass deposited or dissolved during electrolysis.
Enter current, time, and electrode material.
Supports copper, aluminum, silver, gold, and more.
Mass Deposited
Faraday’s First and Second Laws of Electrolysis state:
- The mass of substance deposited is proportional to the charge passed
- The mass deposited per coulomb is proportional to the equivalent weight of the substance
Combined formula:
m = (M × I × t) / (n × F)
Where:
- m = mass deposited (grams)
- M = molar mass of the element (g/mol)
- I = current (amperes, A)
- t = time (seconds)
- n = number of electrons per ion (oxidation state)
- F = Faraday constant = 96,485 C/mol
Also: Q = I × t (charge in coulombs)
Common electrolysis targets:
| Material | Molar Mass (g/mol) | n | Electrode reaction |
|---|---|---|---|
| Copper (Cu) | 63.55 | 2 | Cu²⁺ + 2e⁻ → Cu |
| Silver (Ag) | 107.87 | 1 | Ag⁺ + e⁻ → Ag |
| Gold (Au) | 196.97 | 3 | Au³⁺ + 3e⁻ → Au |
| Aluminum (Al) | 26.98 | 3 | Al³⁺ + 3e⁻ → Al |
| Nickel (Ni) | 58.69 | 2 | Ni²⁺ + 2e⁻ → Ni |
| Zinc (Zn) | 65.38 | 2 | Zn²⁺ + 2e⁻ → Zn |
| Chromium (Cr) | 52.00 | 3 | Cr³⁺ + 3e⁻ → Cr |
Hydrogen and oxygen evolution: At the cathode in water electrolysis: 2H₂O + 2e⁻ → H₂ + 2OH⁻ At the anode: 2H₂O → O₂ + 4H⁺ + 4e⁻ For each mole of H₂: 2 moles of electrons (193,000 C)
Industrial applications:
- Copper refining: electrolytic purification to 99.999% purity
- Aluminum production (Hall-Héroult process): 15 kWh per kg of Al
- Electroplating: thin metal coatings for corrosion resistance and appearance
- Chlor-alkali process: NaCl electrolysis to produce Cl₂ and NaOH