Maxwell thermodynamic derivative relations
Equality of mixed derivatives of smooth equilibrium potentials gives (∂T/∂V)_S=−(∂p/∂S)_V, (∂T/∂p)_S=(∂V/∂S)_p, (∂S/∂V)_T=(∂p/∂T)_V and (∂S/∂p)_T=−(∂V/∂T)_p.
Key knowledge
Equality of mixed derivatives of smooth equilibrium potentials gives (∂T/∂V)_S=−(∂p/∂S)_V, (∂T/∂p)_S=(∂V/∂S)_p, (∂S/∂V)_T=(∂p/∂T)_V and (∂S/∂p)_T=−(∂V/∂T)_p. These relate measurable response coefficients to entropy derivatives.
Values and equations
(∂S/∂V)_T=(∂p/∂T)_V; (∂S/∂p)_T=−(∂V/∂T)_p
- S
- Entropy J K⁻¹
- V
- Volume m³
- T
- Temperature K
- p
- Pressure Pa
Conditions and scope
- Fixed composition, simple compressible system, twice differentiable potentials in the same single-phase domain.
- Across discontinuous phase transitions use the appropriate phase limits and coexistence relations, not unqualified mixed derivatives.
Sources · 4
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Richard Fitzpatrick / University of Texas at Austin4 sources
- Thermodynamics and Statistical Mechanics (2016): Internal energyRichard Fitzpatrick / University of Texas at AustinCourse notes
- Thermodynamics and Statistical Mechanics (2016): EnthalpyRichard Fitzpatrick / University of Texas at AustinCourse notes
- Thermodynamics and Statistical Mechanics (2016): Helmholtz free energyRichard Fitzpatrick / University of Texas at AustinCourse notes
- Thermodynamics and Statistical Mechanics (2016): Gibbs free energyRichard Fitzpatrick / University of Texas at AustinCourse notes
Evidence and review
Thermodynamics and Statistical Mechanics (2016): Internal energy: Equation 6.89. Thermodynamics and Statistical Mechanics (2016): Enthalpy: Equation 6.99. Thermodynamics and Statistical Mechanics (2016): Helmholtz free energy: Equation 6.109. Thermodynamics and Statistical Mechanics (2016): Gibbs free energy: Equation 6.119; reuses existing Gibbs definition.
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