Prigogine's corresponding states approach to equilibrium properties of pure r‐mers is extended to include transport properties. For r‐mer molecules, besides the alike element pair potential parameters, additional quantities are required to characterize the geometrical structure of the molecule and thereby describe more adequately pair potential interactions. As an example, the theory is applied to the homologous series of liquid n‐alkanes. The characteristic parameters for each member of the homologous series are determined using pure component viscosity data at one atmosphere and pure component denstiy data at one temperature and atmospheric pressure. The technique correlates pure component r‐mer transport properties (viscosity — 981 points, thermal conductivity — 216 points) over a wide range of temperature and pressure within experimental error. Using the present technique, available self‐diffusion coefficients are also correlated.
Theorems of corresponding states for predicting the temperature and density dependence of liquid mixture transport properties are presented. The technique is tested for thirteen systems of spherical molecules (eight cryogenic mixtures, and five others) in which viscosity is predicted within 3 %. For cryogenic mixtures, temperatures range from the triple point to temperatures close to the critical. In the present method, the only quantities required are pair potential parameters between like pair interactions, as determined from gas phase viscosity measurements, and pure component data.The lack of accurate measurements of thermal conductivity and diffusivity (mutual or self diffusion coefficients) for mixtures of spherical molecules does not make it possible to test the present theory of those transport properties. ransport properties of liquified simple mixtures are required
An experimental study has been made of the increase in visocisty that occurs for a binary liquid mixture close to the critical mixing point. Viscosities are reported at several temperatures and over the entire cornposition range for the systems phenol+ water, aniline+cyclohexane, methanol+ n-hexane, and methanol+ cyclohexane. Comparison of the experimental results with the predictions of Fixman's theory of the anomalous viscosity effect reveals that the temperature dependence of the excess viscosity is well described by the theory. However, the theory is less successful in predicting the effect of composition on excess viscosity.Near to the critical mixing point of a binary liquid mixture the isothermal viscositycomposition curve shows a maximum. This critical phenomenon has been observed for binary and ternary mixtures of polar and nonpolar liquids,lm6 solutions of salts in mixed solvent^,^ and liquid metals.** Fixman l o * l 1 has presented a theory which accounts for the viscosity anomaly in the critical region, and relates it to the long-range behaviour of the pair correlation function. The equation of Fixman was subsequently rederived by Kawasaki l 2 using the time correlation function approach. Recently a more general theory of the long-range pair correlation function has been presented, l and leads to a modification of the Fixman equation. l 4The present paper describes an experimental study of viscosity in the homogeneous region where anomalous critical behaviour is expected. The four systems studied all have upper critical solution temperatures and are phenol + water, aniline + cyclohexane, methanol + n-hexane, and methanol + cyclohexane. Considerations involved in selecting these particular systems for study included availability of thermodynamic data and convenience of the critical mixing temperature. One purpose of the research was to gather comprehensive data in order to test the above-mentioned theories of the anomalous viscosity. EXPERIMENTAL MATERIALSThe purification of all chemicals is particularly important for studies of critical phenomena, because small traces of impurities have a large effect on the critical mixing temperature.PHENOL was supplied by Eastman Kodak (recrystallized). Gas chromatographic analysis indicated approximately 0.1 % water impurity. This was of little consequence because the system of interest was phenol+ water. Viscosity measurements were made under dark room conditions using red light to minimize decomposition.ANILINE (Baker Analyzed Reagent) was refluxed for 1 h, then twice distilled in the presence of stannous chIoride to remove sulphur compounds.1 Distillation was performed from day to day using a 0-6 m Vigreux column, the fist and last fractions being rejected. Aniline
Prigogine, et al. (1957), developed theorems of corresponding states for thermodynamic properties. Their approach has recently been extended to include transport properties of mixtures of spherical molecules (Brunet and Doan, 1970) as well as pure r-mers (Doan and Brunet, 1972). In the present paper the method is extended to mixtures of r-mer molecules. The technique has been tested for the n-alkanes using the available experimental data: viscosity, 12 sets of data (six systems); thermal conductivity, two sets of data (one system); and diffusivity, 1 3 sets of data (two systems). For these systems transport properties have been predicted within 1-2% of the experimental values and this has been achieved without any mixture parameters.The chief advantages of the present theory lie in the fact that it accounts for the temperature and density (pressure) dependence of the mixture transport properties, and that it is fully predictive and requires no mixture parameters. In the present theory the only quantities required are pair elemental interactions between alike species. In principle, pure component data are not required since a generalized correlation is available from the work of Doan and Brunet (1972). The present work amounts to an extension of earlier works of Brunet and Doan (1970), Tham and Gubbins (1969), Preston, et a/. (1967), and Thomaes (1 959).
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