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We have measured the density of an equimolar gas mixture of CzHs-CH3CI between 323.15 and 473.15 K at pressures to 14.0 MPa. Interaction second virial coefficients and dew-point pressures are extracted from the measurements. Intermolecular force constants for the Lennard-Jones and Stockmayer models are determined optimally for like and unlike pair interactions. Recent methods of prediction for second virial coefficients, both pure and interaction, are tested against experiment. P. T. EUBANK SCOPEFew high-accuracy (better than &0.05%)), density measurements are available for nonpolar/polar gas mixtures over extended ranges of pressure and temperature. Densities (or compressibility factors) are measured to a precision (reproducibility) of &0.01% in modern PVT apparatus; but at reduced temperatures near unity and less, uncertainties due primarily to adsorption errors cause wide differences between precision and estimated accuracy.mixtures with care. Methyl chloride has a high dipole moment but does not hydrogen bond. The methyl chloride/ethane mixture is representative of haloalkane/alkane mixtures, with ethane the homomorph of methyl chloride. Thus the present mixture is a particularly simple nonpolar/polar mixture and a logical beginning for a long-term program of nonpolar/polar measurements. Because of the years of effort and high costs required for each such mixture, it is our rationale to do a few representative CONCLUSIONS AND SIGNIFICANCEThe Burnett mixing technique is shown to yield a mixture mol fraction to f0.0007 (34. Measured densities for the equimolar mixture are considered accurate to f0.04% with a contribution of more than 2~0.03% coming from uncertainties in our adsorption error correction method.Interaction second virial coefficients are calculated from the present mixture second virial coefficients and those of the pure components as published earlier. These values of BIZ have uncertainties, thrice the standard deviation, ranging from 14.4 to 1.8 cm3/mol for temperatures from 323.15 to 473.15 K(50 to 200°C); they are not sufficiently accurate to demonstrate the temperature dependency of klz, the binary interaction constant.Experimental dew-point pressures with uncertainties ranging from 10 to 80 kPa provide a cricondentherm at 399.2 K and 7.55 MPa.The intermolecular pair potentials for CzHe/C&e and CZHB/CH3CI via the Lennard-Jones model represent well the BI1 and B12 macroscopic measurements, while the Stockmayer model is likewise adequate for the CH3CI/CH&I interaction, at least over the present temperature range. Temperature-dependent and orientationdependent effects for the Stockmayer * Correspondence concerning this paper should be addressed to P. T. Eubank. Aleksander Kreglewski died January 1984.potential energy for two methyl ch.aride molecules are also illustrated.The modern predictive methods for pure component second virial coefficients of Tsonopoulos (1974Tsonopoulos ( , 1975Tsonopoulos ( , 1978Tsonopoulos ( , 1979, Hayden and O'Connell(1975), and Tarakad and Danner (1977) provide reas...

Extended operation of a widerange, allmagnetic bearing turbomolecular pump without backing

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