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Faraday constant
Description
The Faraday constant F links the electric charge [C] to amount [mol], and thus relates the electrical format e [C] to the molar format n [mol]. The Farady constant, F = e·N_{A} = 96,485.33 C/mol, is the product of elementary charge, e = 1.602176634∙10^{-19} C/x, and the Avogadro constant, N_{A} = 6.02214076∙10^{23} x/mol. The dimensionless unit [x] is not explicitely considered by IUPAC.
Abbreviation: F [C/mol]
Reference: Gnaiger 2020 MitoPathways
Communicated by Gnaiger E (2019-09-05) last update 2020-11-25
Canonical comments on IUPAC definitions in the context of charge
Charge of the proton versus charge per proton
- Proton charge is the elementary charge e [C·x^{-1}], which is charge Q_{elH+} [C] of protons divided by the count N_{H+} [x] of protons. This distinction is not made sufficiently clear by IUPAC, when defining "-e is the charge of an electron" — it must be corrected to "-e is the charge per electron".
- For comparison, the name "charge density of electrons" is used by IUPAC with symbol ρ [C·m^{-3}]. Dividing ρ by the count concentration of electrons [x·m^{-3}], we obtain the unit [C·x^{-1}] for the electron charge. Therefore, electron charge (or proton charge) is clearly the charge per particle.
Ambiguity of Q_{B}
- IUPAC (Cohen 2008 IUPAC Green Book) defines the charge number as
IUPAC: z_{B} = Q_{B}·e^{-1}
- Therefore, Q_{B} = z_{B}∙e. The subscript in Q_{B} indicates per elementary entity B. This is opposite to the subscript in V_{B} as the symbol for the volume of a substance of type B (e.g. V_{O2} [L]). For consistency with this convention, the symbol Q_{elB} or Q_{elX} [C] is used for indicating charge of a substance of type B or X, distinguished from particle charge as the quantity of charge per elementary entity X with symbol Q_{NX} [C∙x^{-1}]. To avoid too long and multiple subscript levels, Q_{NX} is used instead of Q_{UX}, and the ‘el’ is dropped from Q_{elNX}. The particle charge Q_{NH+} of the proton is defined as elementary charge e. Therefore, the charge number of the proton is z_{H+} = Q_{NH+}/e = 1. In summary:
z_{B} = Q_{NB}·e^{-1}
Q_{NB} = Q_{elB}·N_{B}^{-1} [C∙x^{-1}]
e ≝ Q_{NH+} = Q_{elH+}·N_{H+}^{-1} [C∙x^{-1}]
Keywords
- » charge Q_{elX}
- » charge number z_{X}
- » electrochemical constant f
- » elementary charge e
- » Faraday constant F
- » hydrogen ion versus proton
- » iconic symbols
- » motive entity
- » particle charge Q_{NX}
- Bioblast links: Charge - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
- Normalization of charge and iconic symbols
- Iconic symbols show the quantity, the format of the normalization in the subscript (N, n, e), and the entity specified in the subscript (X). The normalized quantities are per X. In the quantities Q_{elX}, N_{X}, n_{X}, V_{X}, m_{X}, the subscript X without attachment to a format indicates the quantity of X.
Quantity Unit Normalized for quantity Unit Iconic symbol Unit Practical symbol Quantity charge Q_{elX} [C] / count N_{X} [x] = Q_{NX} [C·x^{-1}] particle charge (IUPAC: Q_{B}) charge Q_{elX} [C] / amount n_{X} [mol] = Q_{nX} [C·mol^{-1}] charge number times Faraday constant charge Q_{elX} [C] / volume V_{X} [m^{3}] = Q_{VX} [C·m^{-3}] ρ_{el} charge density charge Q_{elX} [C] / mass m_{X} [kg] = Q_{mX} [C·kg^{-1}] specific charge count N_{X} [x] / charge Q_{elX} [C] = N_{eX} [x·C^{-1}] amount n_{X} [mol] / charge Q_{elX} [C] = n_{eX} [mol·C^{-1}] volume V_{X} [m^{3}] / charge Q_{elX} [C] = V_{eX} [m^{3}·C^{-1}] ρ_{el}^{-1} mass m_{X} [kg] / charge Q_{elX} [C] = m_{eX} [kg·C^{-1}]
- Bioblast links: SI base units - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>
- Entity, count, and number, and SI base quantities / SI base units
Quantity name Symbol Unit name Symbol Comment elementary U_{X} elementary unit [x] U_{X}, U_{B}; [x] not in SI count N_{X} elementary unit [x] N_{X}, N_{B}; [x] not in SI number N - dimensionless = N_{X}·U_{X}^{-1} amount of substance n_{B} mole [mol] n_{X}, n_{B} electric current I ampere [A] A = C·s^{-1} time t second [s] length l meter [m] SI: metre mass m kilogram [kg] thermodynamic temperature T kelvin [K] luminous intensity I_{V} candela [cd]
- Fundamental relationships
- » Avogadro constant N_{A}
- » Boltzmann constant k
- » elementary charge e
- » Faraday constant F
- » gas constant R
- » electrochemical constant f
- Fundamental relationships
- SI and related concepts
References
- Bureau International des Poids et Mesures (2019) The International System of Units (SI). 9th edition:117-216 ISBN 978-92-822-2272-0. - »Bioblast link«
- Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun 2020.2. - »Bioblast link«
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Ergodynamics