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Charge number

Description

The charge number of an ion X or electrochemical reaction with unit stoichiometric number of X is the particle charge [C·x-1] divided by the elementary charge [C·x-1]. The particle charge QNX is the charge per count of ions X or per ion X transferred in the reaction as defined in the reaction equation.

Abbreviation: zX

Reference: Gnaiger 2020 BEC MitoPathways

Communicated by Gnaiger Erich (2020-11-23) last update 2020-12-06
zX = QNX / QNp+
zX = QelX / (e·NX)

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 per count of protons.
QelQelp+ [C]
eQNp+ = Qel·Np+-1  [C∙x-1]
The distinction of charge of particles versus charge per single particle 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 QB

IUPAC (Cohen 2008 IUPAC Green Book) defines the charge number as
IUPAC:  zB = QB·e-1
Therefore, QB = zBe. 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 QNX [C∙x-1]. To avoid too long and multiple subscript levels, QNX is used instead of QUX, and the ‘el’ is dropped from QelNX. The particle charge QNH+ per hydrogen ion is identical to the definition of the elementary charge e. Therefore, the charge number of the hydrogen ion is zH+ = QNH+/e = 1. In summary:
zB = QNB·e-1
QNB = QelB·NB-1 [C∙x-1]

Keywords

» charge QelX
» charge number zX
» electrochemical constant f
» elementary charge e
» hydrogen ion versus proton
» iconic symbols
» motive entity
» particle charge QNX

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 QelX, NX, nX, VX, mX, 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 QelX [C] / count NX [x] = QNX [C·x-1] particle charge (IUPAC: QB)
charge QelX [C] / amount nX [mol] = QnX [C·mol-1] charge number times Faraday constant
charge QelX [C] / volume VX [m3] = QVX [C·m-3] ρel charge density
charge QelX [C] / mass mX [kg] = QmX [C·kg-1] specific charge
count NX [x] / charge QelX [C] = NeX [x·C-1]
amount nX [mol] / charge QelX [C] = neX [mol·C-1]
volume VX [m3] / charge QelX [C] = VeX [m3·C-1] ρel-1
mass mX [kg] / charge QelX [C] = meX [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 UX elementary unit [x] UX, UB; [x] not in SI
count NX elementary unit [x] NX, NB; [x] not in SI
number N - dimensionless = NX·UX-1
amount of substance nB mole [mol] nX, nB
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 IV candela [cd]
Fundamental relationships
» Boltzmann constant k
» elementary charge e
» gas constant R
» electrochemical constant f
SI and related concepts
» International System of Units
» elementary unit x
» SI prefixes
» International Union of Pure and Applied Chemistry, IUPAC
» entity
» quantity
» dimension
» format
» motive unit
» iconic symbols