MOLAR VOLUME AND ULTRASONIC STUDIES OF EUROPIUM SOAPS IN MIXED ORGANIC-SOLVENTS

The ultrasonic velocity and density measurements of europium soaps in a mixture of benzene and methanol (3:2, vol/vol) were used to evaluate various acoustic parameters and molar volume and to determine the cri tical micelle concentration. The results showed that the ultrasonic ve locity, specific acoustic impedance, molar sound velocity, and molar c ompressibility increase, and intermolecular free length, adiabatic com pressibility, and relative association decrease with increasing concen tration and chainlength oi the soap. The results were interpreted in t erms of soap-solvent interaction.