HOME

TheInfoList



OR:

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 The molar gas constant (also known as the gas constant, universal gas constant, or ideal gas constant) is denoted by the symbol or . It is the molar equivalent to the Boltzmann constant, expressed in units of energy per temperature increment per ...
, , do not describe the state of a system, and so are not properties. On the other hand, some constants, such as (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 Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking ** Working animal, an animal t ...
and
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...
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.


See also

*
Conjugate variables Conjugate variables are pairs of variables mathematically defined in such a way that they become Fourier transform duals, or more generally are related through Pontryagin duality. The duality relations lead naturally to an uncertainty relation� ...
* Dimensionless numbers *
Intensive and extensive properties Physical properties of materials and systems can often be categorized as being either intensive or extensive, according to how the property changes when the size (or extent) of the system changes. According to IUPAC, an intensive quantity is one ...
*
Thermodynamic databases for pure substances Thermodynamic databases contain information about thermodynamic properties for substances, the most important being enthalpy, entropy, and Gibbs free energy. Numerical values of these thermodynamic properties are collected as tables or are calcula ...
* Thermodynamic variable


References

{{DEFAULTSORT:List Of Thermodynamic Properties Thermodynamic properties