Faraday
Definition and meaning of Faraday in chemistry.
Faraday (symbol F) is the unit of electric charge equal to the charge carried by one mole of electrons, approximately 96,485 coulombs per mole.
In more detail
It is defined as the product of the Avogadro constant and the elementary charge (F = N_A × e), linking the amount of charge passed through an electrochemical cell to the moles of electrons transferred at the electrodes. This constant underlies Faraday's laws of electrolysis, allowing chemists to calculate the mass of a substance deposited, dissolved, or liberated from a known quantity of charge. The unit honors Michael Faraday, who established the quantitative laws of electrolysis in the 1830s.
Key facts
| Field | Physical Chemistry |
|---|---|
| Symbol | F |
| Value | 96,485 C/mol (approx.) |
| Defined as | F = N_A × e (Avogadro constant × elementary charge) |
Passing one faraday of charge through molten or aqueous silver nitrate deposits one mole of silver metal at the cathode, since the half-reaction Ag+ + e- → Ag requires exactly one mole of electrons per mole of silver.
Frequently asked questions
How is the faraday constant used in electrolysis calculations?
Total charge Q equals n times F, where n is the moles of electrons transferred; dividing the measured charge by F gives moles of electrons, which stoichiometry then converts to moles of product formed.
Is a faraday the same as a farad?
No. The farad (F) is the SI unit of electrical capacitance, while the faraday is a unit of electric charge; both are named after Michael Faraday but measure different quantities.