Viscosities of gaseous mixtures containing polar gases: more than one polar constituent

Abstract

Viscosities of binary and ternary mixtures containing more than one polar gas have been measured at 35 and 80°C. The mixtures investigated are: SO₂+CH₃Cl; SO₂+(CH₃)₂O; CH₃Cl+(CH₃)₂O; SO₂+CH₃Cl+(CH₃)₂O. The apparatus is of the type devised by Thacker and Rowlinson. The accuracy of the measurements is about 1 %. For all three binary mixtures and for the ternary mixture, the experimental values for viscosity do not depart much from the molar average, in contrast to our previous findings for mixtures containing only one polar gas. Calculated values for binary mixtures derived from the first approximation to rigorous theory (Chapman-Enskog equations; parameters evaluated from the simplest combining rules for a Stockmayer 12 : 6 : 3 model) are in excellent agreement with experiment, the average discrepancy (for 52 mixtures) being an overestimate of ca.+0.05 %. For ternary mixtures the agreement is less good, theory providing an average underestimate (for eight ternary mixtures) of 1.35 %. The predictions of the empirical expression of Brokaw are indistinguishable from rigorous theory.