Faraday constant

F = eN_A = 9.64853321233100184×10⁴ C/mol.

Derivation

The Faraday constant can be thought of as the proportionality factor between the charge in coulombs (used in physics and in practical electrical measurements) and the amount of substance in moles (used in chemistry), and is therefore of particular use in electrochemistry, particularly in electrolysis calculations. Because the elementary charge is exactly 1.602176634×10⁻¹⁹ C, and there are exactly N_A = 6.02214076×10²³ entities per mole, the Faraday constant is given by the product of these two quantities:

F = eN_A

= 1.602176634×10⁻¹⁹ C × 6.02214076×10²³ mol⁻¹

= 9.64853321233100184×10⁴ C/mol.

The value of F was first determined in the 1800s 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. Until about 1970, the most reliable value of the Faraday constant was determined by a related method of electro-dissolving silver metal in perchloric acid.