The densities and ultrasonic velocities of binary mixtures of dimethylsulphoxide with isopropyl alcohol, propylene glycol and glycerol have been measured over ...
J. Pure Appl. Ultrason. 21 (1999) pp. 3/-34
Ultrasonic study of molecular interactions in binary liquid mixtures at 303 K ANWAR ALI and ANIL KUMAR NAIN Department of Chemistry, lamia Millia Islamia,
New Delhi-IIO
025
The densities and ultrasonic velocities of binary mixtures of dimethylsulphoxide with isopropyl alcohol, propylene glycol and glycerol have been measured over the entire composition range at 303 K. From these data isentropic compressibility. KS' intermolecular free length. L/ relative association. R".. acoustic impedance, Z, excess isentropic compressibility. K/, and excess free length, have been calculated. The interaction between the component molecules is found to decrease with increasing number of hydroxylic groups in the alcohols.
L/.
Introduction Ultrasonic study of intermolecular interactions between the component molecules in binary liquid mixtures are of considerable theoretical and industrial importance. In continuation of our studies on intermolecular interaction in non-aqueous binary liquid mixtures!", we report here tne results of ultrasonic study of molecular interactions in dirnethylsulphoxide (DMSO) + isopropyl alcohol, + propylene glycol, and + glycerol binary mixtures. DMSO is called "supersolvent" due toits wide range of applicability as solvent in chemical and biological processes. It is highly polar aprotic solvent and its molecules are associated through dipolar interactions'. Isopropyl alcohol, propylene glycol and glycerol are also highly polar but protic solvents. They are self-associated through hydrogen bonding". Literature survey indicates that there is practically no study on binary mixtures of DMSO with isopropyl alcohol, propylene glycol and glycerol from the point view of their ultrasonic behaviour. The dependance of ultrasonic velocity and those of derived parameters such as isentropic: compressibility,
Ks' intermolecular free length, L,. relative association, RA, acoustic impedance, Z, excess isentropic compressibility, KSE, and excess intermolecular free length, LeE, on composition of the binary mixtures throw light on the nature and extent of interaction between the component molecules of these mixtures. With this aim, we determined densities, p, and ultrasonic velocities, u of the binary mixtures under investigation. Using the experimental values of p and u a number of acoustical parameters were calculated in order to study the intermolecular interactions in these systems. Experimental DMSO (E. Merck, Germany) was purified as described in the literature". Isopropyl alcohol, propylene glycol and glycerol (s.d. fine, India, AR) were dried over molecular sieves. All the solutions were prepared by mass in a dry box and were kept in special airtight bottles. The densities were measured using pycnometer of bulb capacity 8 X 10-6 rn! with graduated stem of 5 X 10-8 m3 divisions. The marks on the stem were calibrated using known densities of triple-distilled water. The ultrasonic
