Ultrasonic investigations of binary liquid mixtures of 1,2-propanediol with 1-alkanols at 298.15 K

Abstract
The results of ultrasonic investigations of binary liquid mixtures of 1,2-propanediol with three 1-alkanols, i.e., 1-hexanol, 1-pentanol, and 1-butanol at the temperature 298.15 K are presented. Based on the phase speed of ultrasound values (measured by the pulse-echo-overlap method at 2.18 MHz) and excess molar volumes (taken from the literature), the excess values of the isentropic compressibility coefficients were calculated. Their composition dependencies were expressed by the Redlich-Kister polynomials. It appears that mixing of 1,2-propanediol with 1-hexanol, 1-pentanol, and 1-butanol results in enhanced rigidity in sequence: 1-hexanol, 1-pentanol, and 1-butanol. A comparison with volume and enthalpy changes upon mixing as well as deviations of the speed of ultrasound are discussed too.