By using a ``smoothed potential'' model for the liquid state and assuming isotropic, homogeneous expansion with temperature which involves no change in coordination, it is shown that it is possible to reduce the expression for the configurational energy of the liquid to a function of a single parameter, the density. If the intermolecular forces can be put into a polynomial form then the expression for the configurational energy can be factored, resulting in an algebraic equation of the form: Ec=−B1D2−B2D8/3−B3D−10/3+B4D4 in which D is the molar density and the B's are constants independent of temperature. For the distances occurring in liquids, the last three terms can be either dropped or combined with the first, leaving as an approximation: Ec=ADx/3. The energy of vaporization is given by: Ev=A(D1x/3—Dgx/3 ). Values calculated from this last equation show excellent agreement with experimental values for a large number of both normal and ``abnormal'' liquids. Values of x=5 or 6 both work, the latter bein...
[1]
R. Buckingham,et al.
The Classical Equation of State of Gaseous Helium, Neon and Argon
,
1938
.
[2]
R. M. Barrer.
An Analysis by Adsorption of the Surface Structure of Graphite
,
1937
.
[3]
H. Eyring,et al.
A partition function for liquids
,
1937
.
[4]
J. C. Slater.
The Normal State of Helium
,
1928
.
[5]
H. S. Frank.
Free Volume and Entropy in Condensed Systems I. General Principles. Fluctuation Entropy and Free Volume in Some Monatomic Crystals
,
1945
.
[6]
J. Hirschfelder,et al.
On the theory of the liquid state
,
1937,
Mathematical Proceedings of the Cambridge Philosophical Society.
[7]
E. A. Guggenheim.
On the Statistical Mechanics of Dilute and of Perfect Solutions
,
1932
.
[8]
J. O. Hirschfelder,et al.
Intermolecular Forces and the Properties of Gases.
,
1939
.
[9]
Henry Margenau,et al.
Van der waals forces
,
1939
.