Faraday's Law (Electrolysis) Calculator
Mass deposited during electrolysis.
Formula first
Overview
Faraday's First Law of Electrolysis quantifies the relationship between the mass of a substance produced at an electrode and the total electric charge passed through the electrolytic cell. It established the electrochemical equivalent, proving that chemical changes are directly proportional to the quantity of electricity used in a circuit.
Symbols
Variables
m = Mass Deposited, Q = Charge Passed, M = Molar Mass, F = Faraday Constant, z = Valency
Apply it well
When To Use
When to use: Apply this equation when calculating the yield of a metal during electroplating or determining the time/current required to produce a specific mass of product. It is applicable for DC electrolysis where the reaction stoichiometry and electron transfer per ion are known. It assumes ideal conditions where the current efficiency is 100%.
Why it matters: This principle is the foundation of industrial metallurgy, particularly in the production of aluminum via the Hall-Héroult process and the refining of copper. It allows engineers to predict the efficiency and production rates of chemical manufacturing plants. It also plays a vital role in the design and charging protocols of secondary batteries.
Avoid these traps
Common Mistakes
- Forgetting to include valency z.
- Using wrong units for Q.
One free problem
Practice Problem
Calculate the mass of copper deposited from a CuSO₄ solution when a charge of 5000 Coulombs is passed through the cell. (Copper molar mass = 63.55 g/mol, Valency z = 2).
Solve for:
Hint: Copper in CuSO₄ exists as Cu²⁺ ions, so the valency (z) is 2.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Atkins' Physical Chemistry
- IUPAC Gold Book: Faraday constant
- Wikipedia: Faraday's laws of electrolysis
- NIST CODATA
- IUPAC Gold Book
- Edexcel A-Level Chemistry — Redox and Electrochemistry