Ultrasonic speeds and isentropic functions of ( n-alkoxypropanol + n-alkanol) mixtures at 298.15 K

Abstract

Ultrasonic speeds have been measured in liquid mixtures of ( n-alkoxypropanol + methanol, and 1-propanol) at 298.15 K, as a function of composition. The n-alkoxypropanols were propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol tert-butyl ether. The speed of sound values were combined with those of our previous results for excess molar volumes converted to densities to obtain isentropic compressibility κ s. Deviation in isentropic compressibility Δ κ s were evaluated using volume fraction weighting of the individual component properties to estimate ideal mixture behavior. The Δ κ s values are negative over the entire range of composition for all the mixtures. The deviation of the speeds of sound (Δ u) from their ideal values u id in an ideal mixture were obtained for all measured mole fractions. Also, from these data and viscosity results reported previously, the excess free volume, V f E were calculated for all mixtures. Graphs of Δ κ s, Δ u, and V f E against composition are presented as a basis for a quantitative discussion of the results.