Isothermal compressibility of benzene, deuteriobenzene (C6D6), cyclohexane, and deuteriocyclohexane (c-C6D12), and their mixtures from 0.1 to 35 Mpa at 288, 298, and 313 K

Abstract

The densities of the title compounds and of their solutions (0,25,50,75, and 100 nominal mol %) have been measured between 0.1 and 35 MPa at 15, 25, and 40 OC. The data are reported in terms of the parameters of fit to the Tait equation, and as volumes, compressibilities, K, and reduced compressibilities, KR (KR-I = V/(KRT)), and as excess volumes, excess compressibilities, and excess reduced compressibilities for the solutions. The melting points of C6H12 and C6D12 are reported from 0.1 to 25 MPa. Isotope effects on the volumetric properties of benzene and cyclohexane are small002 and -0.013 & 0.002, respectively), and excess compressibilities for solutions of isotopic isomers, one in the other, are zero within the experimental precision. The data are interpreted in terms of the statistical theory of condensed-phase isotope effects and by using a model which partitions the compressibilities into hard-sphere (HS), librational, internal, and intermolecular attractive parts. Using the model, we calculated the compressibilities, the isotope effects on compressibility, and the excess compressibility of the solutions all in a self-consistent fashion and in agreement with experiment.The sharp heat capacity anomaly in pure sulfur at the polymerization transition is rounded by dopants such as I,, Br,, and C1, far more than can be accounted for by the presence of an inert diluent. We extend the nonclassical scaling theory of the polymerization transition in liquid sulfur based on the n = 0 limit of the n vector model of magnetism to the polymerization of sulfur in the presence of a reactive dopant. A comparison is made among a mean-field theory of doped sulfur, the nonclassical theory, and the experimental data of Feher et al. With use of the parametric equation of state for the n -+ 0 vector model recently employed to describe polymerization of "living" polymers, an improved description of the properties of pure sulfur is obtained.

Correlation of the volumetric properties of fluorinated ethers by the group-contribution volume-ratio method

“…Table 1 lists the flt.orinated ethers for which volumetric property measurements have been made. Van Hook and co-workers determined liquid densities for a series of fluorinated ethels as a function of temperature and pressure in two ways: The first [ 14] employed a Mettler-Paar vibratingtt, be DMA-05 densimeter for (0.1<p<35MPa) and (298<T<the lesser of 373 K or 0.92 T~,), where T~ is the critical temperature; the second employed the (p, I" m, T) apparatus described by Kooner and Van Hook [ 15. 16] for (0.1 < p < 6 MPa) fi'om room temperature to T~..…”

Deuterium isotope differences in 2-propanone, (CH3)2CO/(CD3)2CO: a high-pressure sound-speed, density, and heat capacities study

“…In this work, we report extensive data of several thermophysical properties of acetone-d 6 in broad temperature and pressure ranges, which when combined with those of acetone-h 6 , permit us to test the reliability of a simple statistical-mechanics approach for heat capacitiy isotope effects. Unfortunately, in contrast to the situation encountered regarding many other properties, there is not, to date, a well-established theory for molar volume isotope effects [2][3][4][5][6][7][8][9][10][11][12]. The rather murky procedure of establishing links between molecular structure and density combined with the lack of extensive (and accurate) data on the molar density shifts upon isotopic substitution are the responsible factors.…”

“…While, generally, one can state that, condensed phase IEs are very well interpreted in the light of the quantum-mechanical statistical theory of IEs as originally formulated by Bigeleisen [7] and further developed by Stern et al [8], volumetric and volumerelated properties IEs are currently the least well understood of all IEs on equilibrium physical properties. Matsuo and Van Hook [9] thoroughly investigated the influence of isotopic substitution on the experimental volumetric properties of benzene, cyclohexane and their mixtures, interpreting it in a semi-quantitative fashion. In the same vein, Kooner and Van Hook [3] discussed the high temperature results obtained for acetone.…”

Isotopic effects on non-linearity, molecular radius and intermolecular free length

“…For substances which are associated through hydrogen bonds there are additional reasons for the change in the intermolecular distance when the hydrogen atoms forming these bonds are replaced by deuterium. It has been shown [9,10] that this substitution produces an appreciable change in length of hydrogen bond, i.e. O---O distance.…”