Faraday constant
Physico-chemicalExact
= 96 485.332 12… C mol−1
- Value
- 96 485.332 12… C mol−1
- Standard uncertainty
- exact
- Relative uncertainty
- exact
- Status
- Exact since the 2019 SI redefinition
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
NIST prints this exact value cut to 10 digits. ConstantID recomputes it from the defining constants: 96 485.332 123 310 0184…
Use in a calculation
# Faraday constant, CODATA 2022 (NIST)
F = 9.64853321233100184e4 # C mol^-1, exact
# SciPy: scipy.constants.physical_constants['Faraday constant']What it is
The electric charge carried by one mole of elementary charges, about 96 485 coulombs. It tells an electrochemist how much charge deposits or dissolves a mole of a substance per unit of valence, and appears in the Nernst equation for batteries and electrodes.
It is built only from constants that have exact values since 20 May 2019, so it is exact too; CODATA 2018 was the first adjustment to list it that way.
Equations
- definition
- Nernst equation
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart). Diamonds mark adjustments in which the value was exact.
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 96 485.332 12… | exact | exact |
| 2018 | 96 485.332 12… | exact | −1.3 σ of 2014 |
| 2014 | 96 485.332 89(59) | 6.1 × 10−9 | −1.7 σ of 2010 |
| 2010 | 96 485.3365(21) | 2.2 × 10−8 | −1.4 σ of 2006 |
| 2006 | 96 485.3399(24) | 2.5 × 10−8 | +0.2 σ of 2002 |
| 2002 | 96 485.3383(83) | 8.6 × 10−8 | −0.8 σ of 1998 |
| 1998 | 96 485.3415(39) | 4.0 × 10−8 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).