Diffusion coefficients in binary mixtures of polar gases: sulphur dioxide, dimethyl ether and methyl chloride

Abstract

Binary diffusion coefficients of gases containing more than one polar constituent have been measured at four temperatures 30, 40, 50 and 60°C using the two-bulb technique of Ney and Armistead. The systems investigated were (CH₃)₂O+CH₃Cl; (CH₃)₂O+SO₂ and CH₃Cl+SO₂. Mixtures were analyzed with an MS10 mass spectrometer. The accuracy of the diffusion measurement is about 1.5 %. The experimental diffusion coefficients were used to obtain the unlike interaction parameters on the Stockmayer (12 : 6 : 3) model. The usual combining rules for polar-polar interactions have been found to be only fairly good. Also, the viscosity of these mixtures at 35°C have been calculated using the binary diffusion coefficient and the viscosities of the pure components and the values agree with the experiment satisfactorily.