Collect. Czech. Chem. Commun. 1982, 47, 2170-2179

Application of thermodynamics of systems in a force field to the equilibrium properties of real fluids. Basic relations for pure substances

Emerich Erdös

The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 121 38 Prague 2


The real fluid, between the molecules of which intermolecular forces are acting is regarded as an ideal fluid without molecular interaction situated in an external force field. A force potential is assigned to this virtual force field, and it is shown that all the equilibrium properties of real fluids can be expressed in terms of this virtual potential or/and of its derivatives. Equations are given, expressing the common state functions of pure substances as functions of the virtual potential. In addition, it is shown that close relationships do exist between the approach mentioned above and the known fundamental approaches, such as the dynamical and statistical-mechanical one. Therefrom it is evident that the approach proposed here represents an additional alternative for the description of equilibrium properties of fluids which is equivalent to the existing approaches from the formal point of view.