Reaction Gibbs energy and reversible cell work
For a balanced redox reaction transferring n electrons per reaction event, the molar reaction Gibbs energy is ΔrG=−nFE at the same temperature and composition when E is its reversible cell potential.
Key knowledge
For a balanced redox reaction transferring n electrons per reaction event, the molar reaction Gibbs energy is ΔrG=−nFE at the same temperature and composition when E is its reversible cell potential. Thus ΔrG°=−nFE° and ln K=nFE°/(RT) under consistent dimensionless activity and standard-state conventions. Multiplying the balanced reaction multiplies n and ΔrG but does not multiply E.
Values and equations
ΔrG=−nFE; ΔrG°=−nFE°; ln K=nFE°/(RT)
- ΔrG,ΔrG°
- molar reaction Gibbs energy at actual and standard compositions J mol⁻¹
- n
- electron count for the stated balanced reaction 1
- F
- Faraday constant C mol⁻¹
- E,E°
- reversible and standard cell potentials V
- K
- dimensionless thermodynamic equilibrium constant 1
- R
- molar gas constant J mol⁻¹ K⁻¹
- T
- absolute temperature K
Conditions and scope
- Use n>0 and a fixed direction for the balanced reaction; Gibbs energies are per mole of that reaction extent.
- These equilibrium work relations exclude current-dependent ohmic losses and activation/concentration overpotential; favourable Gibbs energy does not guarantee rapid current.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read E°/ΔG° electron-charge work and equilibrium relations and independently combined ΔrG°=−RTlnK. Defined work as reversible non-expansion work at fixed temperature/pressure, avoiding source's unqualified maximum-work wording; excluded dated Faraday numerical value.
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Entry details
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- uni-chem-reversible-electrical-work
- Revision
- core.1
- Structured reference record
- University core expansion