ULTRASONIC SPEEDS AND VOLUMETRIC PROPERTIES OF BINARY-MIXTURES OF WATER WITH 2-[2-(2-ALKOXYETHOXY)ETHOXY]ETHANOLS AT 298.15K

Density and ultrasonic speed measurements have been made using vibrati ng tube densimeters and by a sonic solution monitor using a 'pulse-ech o-overlap' technique, respectively, for aqueous mixtures of 2-[2-(2-et hoxyethoxy)ethoxy]ethanol and 2-[2-(2b butoxyethoxy)ethoxy]ethanol, at 298.15 K, across the entire composition range. The density values wer e readily converted to molar volumes, V, and excess molar volumes, V-E . Estimates of the isentropic molar quantity, K-S, equal to -(partial derivative V/partial derivative(P))(S), and of its excess counterpart, K-S(E) were obtained from the density values, in combination with the ultrasonic speed values. The magnitude of V-E decreases with the alky l-chain length, except in the water-rich region. The composition depen dence of K-E(S) shows a similar decrease. Data reduction procedures we re used to calculate several related quantities leading to graphs with enhanced visual impact. Results were compared with those reported ear lier for 2-[2-(2-methoxyethoxy)ethoxy]ethanol-water and 2-[2-(2-hexylo xyethoxy)ethoxy]ethanol-water, and for 2-butoxyethanol-water and 2-(2- butoxyethoxy)ethanol-water. Graphs of the data sets are presented as a basis for discussion of evidence for prevailing patterns of molecular aggregation. Segmented-composition models, including a version onto w hich a mass-action component has been grafted, were used to analyse th e various excess molar quantities.