Study of molecular interaction in ternary mixtures through ultrasonic speed measurements

Abstract

Density (ρ) and ultrasonic speed (u) of ternary liquid mixtures: acetonitrile (ACN) + 1-propanol + benzene, + toluene, + chlorobenzene and + nitrobenzene, and those of pure components, have been measured as function of composition at 303.15 K. Using experimental data, the values of isentropic compressibility (K s ), intermolecular free length (L f ), molar ultrasonic speed (R m ), acoustic impedance (Z), excess isentropic compressibility ( ), excess free length ( ), excess volume (V E ) and excess acoustic impedance (Z E ) were computed. The increase or decrease of K s , L f , R m and Z with composition indicates the presence of interaction between the component molecules in the mixtures. The excess functions and V E are predominantly negative, while Z E is almost positive. This further supports the presence of significant interactions between the component molecules in these mixtures. Theoretical values of ultrasonic speed have been calculated for all the four ternary mixtures at different compositions using free length theory (FLT), collision factor theory (CFT), Nomoto's (NOM) empirical relation and Van Dael and Vangeel (VDV) ideal mixing relation. A comparison of theoretical values of ultrasonic speed with those obtained experimentally reveals that, in general, CFT predicts the data reasonably well.