# 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. Properties is defined as the characteristic feature of a system by which it can be specified. 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 a  –
Chemical potential μi kJ/mol   Particle
number Ni
Compressibility (isothermal) βT, κ Pa−1
Cryoscopic constant Kf K·kg/mol
Density ρ kg/m3
Ebullioscopic constant Kb K·kg/mol
Enthalpy H J
Specific enthalpy h J/kg
Entropy S J/K   Temperature T   (entropic)
Specific entropy s J/(kg K)
Fugacity f N/m2
Gibbs free energy G J
Specific Gibbs free entropy g J/(kg K)
Gibbs free entropy Ξ J/K     (entropic)
Grand / Landau potential Ω J
Heat capacity (constant pressure) Cp J/K
Specific heat capacity
(constant pressure)
cp J/(kg·K)
Heat capacity (constant volume) Cv J/K
Specific heat capacity
(constant volume)
cv J/(kg·K)
Helmholtz free energy A, F J
Helmholtz free entropy Φ J/K     (entropic)
Internal energy U J
Specific internal energy u J/kg
Internal pressure πT Pa
Mass m kg
Particle number Ni  –   Chemical
potential μi
Pressure p Pa   Volume V
Temperature T K   Entropy S
Thermal conductivity k W/(m·K)
Thermal diffusivity α m2/s
Thermal expansion (linear) αL K−1
Thermal expansion (area) αA K−1
Thermal expansion (volumetric) αV K−1
Vapor quality χ  –
Volume V m3   Pressure P
Specific volume v m3/kg