Binary Mixtures of Benzene and Cyclohexane with <i>n</i>-Alkyl Functional Groups up to 12 Carbons Long: Densities, Viscosities, and Speeds of Sound within the Temperature Range (288.15–333.15) K

Abstract

The densities, viscosities, and speeds of sound of equimolar binary mixtures of benzene and n-alkylbenzenes, cyclohexane and n-alkylcyclohexanes, and n-alkylbenzenes and n-alkylcyclohexanes were measured. As the alkyl group on the molecules increased, densities, viscosities, and speeds of sound in mixtures increased, except for some mixtures with toluene and methylcyclohexane, where the property was the lowest of the mixture series. Excess molar volumes (VmE’s) were positive for all mixtures, and their values decreased with increasing alkyl chain length for mixtures of alkylbenzenes in cyclohexane or alkylcyclohexanes. For benzene mixtures, VmE’s increased with increasing alkyl chain length on cyclohexane, except for methylcyclohexane, which had the lowest VmE in the series. Viscosity deviations (Δη’s) were negative. As the alkyl group on the molecules increased, Δη increased to a maximum and then decreased to its lowest value. Excess isentropic compressibilities (KE’s) determined from density, speed of sound, and literature heat capacities were positive for benzene/cyclohexane mixtures. In general, KE’s decreased with increasing alkyl chain length for all mixtures. The similar trend in VmE’s and KE’s for the alkylbenzene mixtures suggests that the greater expanded volume allows for greater compressibility. For benzene mixtures, decreasing KE’s corresponded to increasing VmE’s, which suggests a complex packing arrangement.

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