113-123Viscosities of three quaternary, viz. n-hexadecane + n-tetradecane + n-hexane + 2-bromobutane (I), n-hexadecane + carbon tetrachloride + benzene + n-hexane (II) and n-hexadecane + n-tetradecane + 4-methylcyclohexanone + n-hexane (III) and eleven ternary liquid mixtures (IA-D, IIA-D and IIIA-C) have been evaluated theoretically, using various empirical relations (Frenkel, Kendall-Munroe, Bingham and Additive relations) applicable to binary mixtures. The theoretical values of viscosity of these mixtures are compared with the experimental viscosities given in literature. The results of calculation show that the viscous behaviour of these liquid mixtures having constituent components with likelihood of better interactions with each other, can be best explained by Frenkel relation as it takes into account all the possible major interactions. Still better results by Frenkel relation are obtained when some small molecules like CCl4 is one of the components of the mixture (II) which can take up interstitial positions resulting in enhanced interaction. The presence of planar molecules, like benzene with its 3t-electron cloud above and below the ring, certainly inhibits the interaction between the components to some extent and results in somewhat ideal behaviour of mixtures. This is evident for some systems where Kendall-Munroe and Additive relations give better results than those given by Frenkel relation. The presence of substituent and polar groups on one of the components affects the extent of interaction more than when they are present in a cyclic molecule than on a straight chain hydrocarbon. Thus, the presence of bromine in system (I) and the ternary mixtures still allows interaction to a greater extent since in the possible compact structure 2-bromobutane can fit with bromine protruding out. However, the presence of polar and substituent groups in cyclic molecule (4-methylcyclohexanone) does not allow interaction and also inhibits the interaction of other components resulting in ideal mixing and thus better
