Ultrasonic Study of Intermolecular Interactions on Non-Aqueous Binary Liquid Mixtures at 30°C

The ultrasonic speeds, U and densities, ρ of pure benzene, n-butanol, iso-butanol, sec-butanol and tert-butanol and their binary mixtures with benzene as a common component were measured at 30°C over the whole composition range. The dependence of ultrasonic speed on composition of the mixture was checked by using an empirical relation. From the experimental data, the values ofisentropic compressibility, ks, intermolecular free length, L_f, relative association, R_A, acoustic impedance, Z, molar sound speed, R_m, deviations in isentropic compressibility, Δk_s, excess intermolecular free length, L^E_f, deviations in ultrasonic speed, ΔU, excess acoustic impedance, Z^E, apparent molar compressibilities, K_∅,1 and K_∅,2 and partial molar compressibilities, ̅K°_∅,1 and ̅K°_∅,2 of benzene in alcohols and alcohols in benzene, respectively, at infinite dilution were calculated. The variation of these parameters with composition indicates the presence of weak interactions between the component molecules and this interaction decrease in the order: n-butanol>iso-butaitol>sec-butanol>tert-butanol. Further, the ultrasonic speeds in these mixtures were theoretically calculated with the help of several theories and empirical relations by using data on pure components. The relative merits of these theories and relations for the present systems have been discussed.