# List of thermodynamic properties

In thermodynamics, a physical property is any property that is measurable, and whose value describes a state of a physical system. Thermodynamic properties are defined as characteristic features of a system, capable of specifying the system's state. 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 therefore 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 need 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 (adiabatic) βS, κ Pa−1 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 