# List of thermodynamic properties

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Within thermodynamics, a physical property is any property that is measurable, and whose value describes a state of a physical system. Some constants, such as the ideal gas constant, R, do not describe the state of a system, and so are not properties. On the other hand, some constants, such as Kf (the freezing point depression constant, or cryoscopic constant), depend on the identity of a substance, and so may be considered to describe the state of a system, and so may be considered physical properties.

"Specific" properties are expressed on a per mass basis. If the units were changed from per mass to, for example, per mole, the property would remain as it was (i.e., intensive or extensive).

Regarding Work and Heat

Work and heat are not thermodynamic properties, but rather process quantities: flows of energy across a system boundary. Systems do not contain work, but can perform work, and likewise, in formal thermodynamics, systems do not contain heat, but can transfer heat. Informally, however, a difference in the energy of a system that occurs solely because of a difference in its temperature is commonly called heat, and the energy that flows across a boundary as a result of a temperature difference is "heat".

Altitude (or elevation) is usually not a thermodynamic property. Altitude can help specify the location of a system, but that does not describe the state of the system. An exception would be if the effect of gravity needed to be considered in order to describe a state, in which case altitude could indeed be a thermodynamic property.

Thermodynamic properties and their characteristics
Property Symbol Units Extensive? Intensive? Conjugate Potential?
Activity ${\displaystyle a}$  –
Chemical potential ${\displaystyle \mu _{i}}$ kJ/mol Particle
number ${\displaystyle N_{i}}$
Compressibility (adiabatic) ${\displaystyle \beta _{S}}$, ${\displaystyle \kappa }$ Pa−1
Compressibility (isothermal) ${\displaystyle \beta _{T}}$, ${\displaystyle \kappa }$ Pa−1
Cryoscopic constant[1] ${\displaystyle K_{f}}$ K·kg/mol
Density ${\displaystyle \rho }$ kg/m3
Ebullioscopic constant ${\displaystyle K_{b}}$
Enthalpy ${\displaystyle H}$ J
Specific enthalpy ${\displaystyle h}$ J/kg
Entropy ${\displaystyle S}$ J/K Temperature ${\displaystyle T}$ (entropic)
Specific entropy ${\displaystyle s}$ J/(kg K)
Fugacity ${\displaystyle f}$ N/m²
Gibbs free energy ${\displaystyle G}$ J
Specific Gibbs free entropy ${\displaystyle g}$ J/(kg K)
Gibbs free entropy ${\displaystyle \Xi }$ J/K (entropic)
Grand / Landau potential ${\displaystyle \Omega }$ J
Heat capacity (constant pressure) ${\displaystyle C_{p}}$ J/K
Specific heat capacity
(constant pressure)
${\displaystyle c_{p}}$ J/(kg·K)
Heat capacity (constant volume) ${\displaystyle C_{v}}$ J/K
Specific heat capacity
(constant volume)
${\displaystyle c_{v}}$ J/(kg·K)
Helmholtz free energy ${\displaystyle A}$, ${\displaystyle F}$ J
Helmholtz free entropy ${\displaystyle \Phi }$ J/K (entropic)
Internal energy ${\displaystyle U}$ J
Specific internal energy ${\displaystyle u}$ J/kg
Internal pressure ${\displaystyle \pi _{T}}$ Pa
Mass ${\displaystyle m}$ kg
Particle number ${\displaystyle N_{i}}$  – Chemical
potential ${\displaystyle \mu _{i}}$
Pressure ${\displaystyle p}$ Pa Volume ${\displaystyle V}$
Temperature ${\displaystyle T}$ K Entropy ${\displaystyle S}$
Thermal conductivity ${\displaystyle k}$ W/(m·K)
Thermal diffusivity ${\displaystyle \alpha }$ m²/s
Thermal expansion (linear) ${\displaystyle \alpha _{L}}$ K−1
Thermal expansion (area) ${\displaystyle \alpha _{A}}$ K−1
Thermal expansion (volumetric) ${\displaystyle \alpha _{V}}$ K−1
Vapor quality[2] ${\displaystyle \chi }$  –
Volume ${\displaystyle V}$ m3 Pressure ${\displaystyle P}$
Specific volume ${\displaystyle v}$ m3/kg