Faraday constant
Faraday constant | ||
---|---|---|
Value | 9.64853321233100184×104 C⋅mol−1 |
In
- F = e × NA
- = 1.602176634×10−19 C × 6.02214076×1023 mol−1
- = 9.64853321233100184×104 C⋅mol−1.
- Or
- = 96500 C/mol
Derivation
The Faraday constant can be thought of as the conversion factor between the mole (used in chemistry) and the coulomb (used in physics and in practical electrical measurements), and is therefore of particular use in electrochemistry. Because there are exactly NA = 6.02214076×1023 entities per mole,[1] and there are exactly 1/e = 1019/1.602176634 elementary charges per coulomb,[1] the Faraday constant is given by the quotient of these two quantities:
- F = NA/1/e = 9.64853321233100184×104 C⋅mol−1.
One common use of the Faraday constant is in electrolysis calculations. One can divide the amount of charge (the current integrated over time) by the Faraday constant in order to find the chemical amount of a substance (in moles) that has been electrolyzed.
The value of F was first determined in the 1800s by weighing the amount of
Other common units
- 96.485 kJ per volt–gram-equivalent
- 23.061 kcal per volt–gram-equivalent
- 26.801 A·h/mol
Faraday – a unit of charge
Related to the Faraday constant is the "faraday", a unit of
- 1 faraday = F × 1 mol = 9.64853321233100184×104 C
Conversely, the Faraday constant F equals 1 faraday per mole.
The faraday is not to be confused with the farad, an unrelated unit of capacitance (1 farad = 1 coulomb / 1 volt).
Popular media
The Simpsons episode "Dark Knight Court" has Mr. Burns asking Comic Book Guy how much he wants for his entire comic book inventory. He says "the speed of light expressed as dollars" and Mr. Burns tells Smithers to "just give him Faraday's Constant". The check is written for $96,485.34.
See also
- electrical capacitance
- Faraday efficiency
- Faraday's laws of electrolysis
- Faraday cup