Electrochemical Equivalent
Definition and meaning of Electrochemical Equivalent in chemistry.
Electrochemical equivalent is the mass of a substance that is deposited or liberated at an electrode when one coulomb of electric charge passes through an electrolytic cell. It is a quantitative measure derived from Faraday's laws of electrolysis.
In more detail
The electrochemical equivalent (abbreviated ECE or z) is calculated using the formula z = M/(nF), where M is the molar mass of the element in grams per mole, n is the number of electrons transferred per atom or ion, and F is Faraday's constant (96,485 coulombs per mole). This constant allows chemists and engineers to predict precisely how much metal or other substance will be deposited during electroplating, electrorefining, and electrometallurgical processes. The electrochemical equivalent is expressed in grams per coulomb (g/C), making it a practical tool for industrial electrochemistry.
Key facts
| Field | Physical Chemistry |
|---|---|
| Unit | grams per coulomb (g/C) |
| Formula | z = M/(nF) |
| Related Constant | Faraday's constant = 96,485 C/mol |
Copper has an electrochemical equivalent of approximately 0.000329 g/C. During the electroplating of an object in a copper sulfate (CuSO4) solution, exactly 1 coulomb of current deposits roughly 0.329 milligrams of copper metal onto the cathode.
Frequently asked questions
How is electrochemical equivalent used in electroplating?
It allows manufacturers to calculate the exact amount of metal deposited over time. By multiplying the electrochemical equivalent by the total charge (current × time), engineers can control coating thickness and quality precisely.
Why do different metals have different electrochemical equivalents?
Because electrochemical equivalent depends on molar mass and the number of electrons transferred. Lighter elements or those with higher electron transfers per atom have smaller ECE values and deposit less mass per coulomb.