Template:Keywords: Charge
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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 [Cยทx-1], which is charge QelH+ [C] of protons divided by the count NH+ [x] of protons. This distinction is not made sufficiently clear by IUPAC, when defining "-e is the charge of an electron" โ 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 ฯ [Cยทm-3]. Dividing ฯ by the count concentration of electrons [xยทm-3], we obtain the unit [Cยทx-1] for the electron charge. Therefore, electron charge (or proton charge) is clearly the charge per particle.
Ambiguity of QB
- IUPAC (Cohen 2008 IUPAC Green Book) defines the charge number as
IUPAC: zB = QBยทe-1
- Therefore, QB = zBโe. The subscript in QB indicates per elementary entity B. This is opposite to the subscript in VB as the symbol for the volume of a substance of type B (e.g. VO2 [L]). For consistency with this convention, the symbol QelB or QelX [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 QUX [Cโx-1]. To avoid too long and multiple subscript levels, QUX is used instead of QUX, and the โelโ is dropped from QelUX. The particle charge QUH+ of the proton is defined as elementary charge e. Therefore, the charge number of the proton is zH+ = QUH+/e = 1. In summary:
zB = QUBยทe-1
QUB = QelBยทNB-1 [Cโx-1]
e โ QUH+ = QelH+ยทNH+-1 [Cโx-1]
Keywords
- ยป charge QelX
- ยป charge number zX
- ยป electrochemical constant f
- ยป elementary charge e
- ยป Faraday constant F
- ยป particle charge QUX
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- Normalization of charge and canonical symbols
Quantity Unit Normalized for quantity Unit Canonical symbol Unit Practical symbol Quantity charge QelX [C] / count NX [x] = QUX [Cยทx-1] particle charge (IUPAC: QB) charge QelX [C] / amount nX [mol] = QnX [Cยทmol-1] charge number times Faraday constant charge QelX [C] / volume VX [m3] = QVX [Cยทm-3] ฯel charge density charge QelX [C] / mass mX [kg] = QmX [Cยทkg-1] specific charge count NX [x] / charge QelX [C] = NeX [xยทC-1] amount nX [mol] / charge QelX [C] = neX [molยทC-1] volume VX [m3] / charge QelX [C] = QVX [m3ยทC-1] ฯel-1 mass mX [kg] / charge QelX [C] = MeX [kgยทC-1]