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

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 κs. Deviation in isentropic compressibility Δκs were evaluated using volume fraction weighting of the individual component properties to estimate ideal mixture behavior. The Δκs values are negative over the entire range of composition for all the mixtures. The deviation of the speeds of sound (Δu) from their ideal values uid in an ideal mixture were obtained for all measured mole fractions. Also, from these data and viscosity results reported previously, the excess free volume, VfE were calculated for all mixtures. Graphs of Δκs, Δu, and VfE against composition are presented as a basis for a quantitative discussion of the results.