Faraday Constant Definition

The Faraday constant is the electrical charge of one mole of electrons.
The Faraday constant is the electrical charge of one mole of electrons. GEOFF TOMPKINSON/SCIENCE PHOTO LIBRARY / Getty Images

The Faraday constant, F, is a physical constant equal to the total electric charge carried by one mole of electrons. The constant is named for English scientist Michael Faraday. The accepted value of the constant is:

  • F = 96,485.3365(21) C/mol
  • F = 96 485.3329 s A / mol
  • F = 23.061 kcal per volt gram equivalent
  • F = 26.801 A·h/mol

Initially, the value of F was determined by weighing the mass of silver deposited in an electrochemical reaction in which the amount and duration of current was known.

The Faraday constant is related to Avogadro's constant NA and the elementary charge of an electron by the equation:

F = NA

where:

e ≈ 1.60217662×10−19 C

NA ≈ 6.02214086×1023 mol−1

Faraday's Constant vs Faraday Unit

The "faraday" is a unit of electrical charge that is equal to the magnitude of the charge of a mole of electrons. In other words, the Faraday constant equals 1 faraday. The "f" in the unit is not capitalized, while it is when referring to the constant. The faraday is rarely used, in favor of the SI unit of charge, the coulomb.

An unrelated units is the farad (1 farad = 1 coulomb / 1 volt), which is a unit of capacitance, also named for Michael Faraday.