Virial expansion(2.19)—This is a theoretically grounded equation of state, which means
that accurate relations between the virial coefficients and intermolecular forces are
known. In practice it is applied in such a way that the virial coefficients are substituted
by empirical relations (usually polynomials in 1/T). With a large number of constants
this equation allows for a good description of the behaviour or both gases and liquids.
Pressure virial expansion(2.20)—This equation is usually applied only with the second
virial coefficient. In this case it is used in the same range as the equation of state of an
ideal gas, but it provides more accurate results.
Van der Waals equation of state(2.23)—Its importance is only historical, it is usually
not applied in practice. Its simplicity predetermines it for use in teaching.
Redlich-Kwong equation of state(2.27)—One of the most popular equations of state for
gases. Some of its modifications are applied in current practice.
Benedict, Webb and Rubin equation of state(2.32)—One of the best equations of state for
the gas range. However, it is little accurate in the range of liquid, where it is substituted
by its modifications with a larger number of constants (20 and even more).
The theorem of corresponding states(2.33)—The two-parameter theorem presented here
(the two parameters areTcandpc) allows for estimating state behaviour with an error
of about 5 percent.
