Calculation of the mean force constants of the rare gases and the rectilinear law of mean force

Abstract

The mean energies, <U>, and the mean force constants, <V U>, have been calculated for liquid argon and liquid krypton using the WCA perturbation theory,and for gaseous argon and krypton along the coexistence line by solution of the PY equation for the radial distribution function. Calculations have been made for the Lennard-Jones, Barker-Henderson and Maitland-Smith potentials.

Temperature Dependence of the Liquid-Vapor Isotopic Fractionation Factors in CD3H-CH4 and CD3F-CH3F Mixtures

“…The method assumes that the intermolecular potential is pairwise additive and utilizes a power series expansion of the pair correlation function in the particle density up to terms in g2 [27], From these assumptions one obtains (is) A vlc <vn>-<viv>= --r-2 fo-evHßc+yitei+ßv)]» where ^vic = « v ic>-vig) and yt is the coefficient of g2 in the power series expansion, v-is the frequency in the ideal gas. Lee and Bigeleisen [13] found the coeffi cient of £2 for the power series expansion of <T2 U} to be close to one. <02 (7) is a least quadratic in the density [15].…”

“…We extend the method [13] used to obtain the tem perature dependence of « F 2(7>, -<F2L/)V ) to develop the temperature dependence of <vn> -<viv>. The method assumes that the intermolecular potential is pairwise additive and utilizes a power series expansion of the pair correlation function in the particle density up to terms in g2 [27], From these assumptions one obtains (is) A vlc <vn>-<viv>= --r-2 fo-evHßc+yitei+ßv)]» where ^vic = « v ic>-vig) and yt is the coefficient of g2 in the power series expansion, v-is the frequency in the ideal gas.…”

“…Along the coexistence line of the liquid, from the triple point to the critical temperature, one finds from experiment and with the oretical justification [13] <V2U*) = C g*(\+g*),…”

“…Experimental measurements of the VPIE and LV IFF in the condensed rare gases, particularly argon, which cover the range from the low temperature solid through the melting point and to within 0.4 K of the critical temperature [4], and theoretical studies [13] established the temperature dependence of <V2U \ -<F2C/)v) for the rare gases. Along the coexistence line of the liquid, from the triple point to the critical temperature, one finds from experiment and with the oretical justification [13] <V2U*) = C g*(\+g*),…”

Isotopic krypton mixtures revisited: Vapor pressure isotope effects

“…Also, ٌ͗ 2 U͘ l was approximated to follow the relation ٌ͗ 2 U͘ l Vϭconstant, where V is the molar volume of the liquid along the orthobaric line. Enhanced generality can be achieved if one assumes instead 13,14 that ٌ͗ 2 U͘ l /͓*(1ϩ*)͔ϭconstant, where * is the reduced liquid density along the orthobaric line. Under this latter circumstance one obtains, 7,15…”