coulomb per mole
Molar chargeexact by definition
The coulomb per mole is the SI unit of molar charge, and its factor of 1 is exact. Its defining value is the Faraday constant, the charge on one mole of electrons, which since 2019 is exactly 96 485.332 12 C/mol because both the elementary charge and the Avogadro number are now fixed by definition. It is the conversion between electricity used and substance transformed in any electrochemical process.
Watch out: Divide by the number of electrons in the half-reaction. Depositing copper from Cu²⁺ takes two faradays per mole, not one, so 96 485 C plates half a mole of copper. Getting the electron count wrong is the standard error in electroplating and corrosion-rate calculations.
| 1 C/mol | 1 C/mol |
Named for Michael Faraday, whose laws of electrolysis in the 1830s established that the mass deposited at an electrode is proportional to the charge passed and to the equivalent weight of the substance.