Volumetric properties of binary mixtures of water with methoxy(ethoxy)_nethanols

Abstract

Density and ultrasonic speed measurements have been made, respectively, by means of a densimeter operating in a flow mode and by a sonic solution monitor using a 'sing-around' technique, for aqueous mixtures of 2-(2-methoxyethoxy)ethanol and 2-[2-methoxy(ethoxy),lethanol, at 298.15 K, across the entire composition range. The density values were readily converted to molar volumes, V, and excess molar volumes, VE. Estimates of the isentropic molar quantity, K,, equal to -(aV/ap), , and of its excess counterpart, KE, have been obtained from the density values, in combination with the ultrasonic speed values. The magnitude of VE increases with the introduction of oxyethylene groups into the molecule of amphiphile. The composition dependence of KE shows a similar increase, but one that is limited to the water-rich region. Data reduction procedures have been used to calculate several related quantities leading to graphs with enhanced visual impact. Our results have been compared with those reported earlier for methanol-water, and 2-methoxyethanol-water. Graphical analyses of the data sets are presented in an effort to find a plausible rationale for the observed trends in terms of prevailing patterns of molecular aggregation, while the various excess quantities considered are analysed using a segmented-composition model.

Speeds of sound and isentropic compressibilities of (n-alkoxyethanols+ toluene) at T= 298.15 K

“…2 ) 2 OH 1016.4 1016.7 (12) 100.4 * 271.1 (12) 1417.1 1415.98 (17) 57.915 1014.45 (17) (18) 115.4 (19) 298.1 (19) 1377.1 1377.22 (19) 73.087 983.589 (19) 984.1 (12) (18) 144.2 (19) 358.4 (19) 1358.3 1357.02 (19) …”

Ultrasonic speeds and volumetric properties of binary mixtures of water with poly(ethylene glycol)s at 298.15 K

“…Minima of this type are a typical characteristic of amphiphileÈwater systems. 6 The changes with of the partial excess molar volumes for x A water, in the water-rich region of the di †erent mixtures V W E , are plotted in Fig. 3.…”

“…It has been shown that the inclusion of one or more oxyethylene groups into an amphiphile molecule increases the LCST and consequently the aqueous miscibility.4,5 The e †ects of enlarging the polar head group by progressive addition of oxyethylene groups into molecules of amphiphiles with di †erent alkylchain lengths were previously explored. 6,7 We thought it worthwhile to measure their magnitude when no alkyl chain is involved in the amphiphile molecule. Consequently, this work explores these e †ects for binary aqueous mixtures of poly (…”

New thermodynamic relations concerning apparent molar isentropic compression and apparent and partial isentropic compressibilities

“…( 27) and (30), and with higher-order partial properties9 in eqn. (31) and (32). A terminology that distinguishes volume-speciÐc quantities6 from quantities speciÐc in the total amount of substance is suggested.…”