Faraday constant

In physics and chemistry, the Faraday constant (named after Michael Faraday) is the magnitude of electric charge per mole of electrons. It has the currently accepted value

F = 96,485.3365(21) C/mol.

The constant F has a simple relation to two other physical constants:

$F\,=\,eN_{A}$

where:

e ≈ 1.6021766×10⁻¹⁹ C;

N_A ≈ 6.022141×10²³ mol⁻¹.

N_A is the Avogadro constant (the ratio of the number of particles 'N' to the amount of substance 'n' - a unit mole), and e is the elementary charge or the magnitude of the charge of an electron. This relation is true because the amount of charge of a mole of electrons is equal to the amount of charge in one electron multiplied by the number of electrons in a mole.

The value of F was first determined by weighing the amount of silver deposited in an electrochemical reaction in which a measured current was passed for a measured time, and using Faraday's law of electrolysis. Research is continuing into more accurate ways of determining the interrelated constants F, N_A, and e.

Other Common Units of Faraday's Constant

• 96,485 J (96.485 kJ) per volt gram equivalent
• 23.061 kcal per volt gram equivalent
• 26.801 A*h/mol

Faraday unit of charge

Related to Faraday's constant is the "faraday", a unit of electrical charge. It is much less common than the coulomb, but sometimes used in electrochemistry. One Faraday of charge is the magnitude of the charge of one mole of electrons, i.e. 96,485.3365(21) C.

Expressed in faradays, the Faraday constant F equals "1 faraday of charge per mole".

This faraday unit is not to be confused with the farad, an unrelated unit of capacitance.

See also

• Farad, unit of capacitance
• Michael Faraday
• Faraday cage
• Faraday efficiency
• Faraday's law of electrolysis
• Faraday's law of Electromagnetic induction