Virial equation of state
The virial equation of state is used to describe the behavior of diluted gases. It is usually written as an expansion of the compressibility factor, , in terms of either the density or the pressure. Such an expansion was first introduced by Kammerlingh Onnes. In the first case:
- .
where
- is the pressure
- is the volume
- is the number of molecules
- is the (number) density
- is called the k-th virial coefficient
Virial coefficients
The second virial coefficient represents the initial departure from ideal-gas behavior
where is Avogadros number and and are volume elements of two different molecules in configuration space.
One can write the third virial coefficient as
where f is the Mayer f-function (see also: Cluster integrals).
References
- H. Kammerlingh Onnes "", Communications from the Physical Laboratory Leiden 71 (1901)
- James A Beattie and Walter H Stockmayer "Equations of state", Reports on Progress in Physics 7 pp. 195-229 (1940)