Determination of Electrolyte Apparent Molal Compressibilities at Infinite Dilution Using a High-Precision Ultrasonic Velocimeter

. Can. J. Chem. 65, 810 (1987). Ultrasonic velocity and density data of binary systems of water-2-butoxyethanol (BE), 2-butoxyethanol-benzene, and 2-butoxyethanol-decane are reported for temperatures of 25, 40, and 55°C. Adiabatic compressibility coefficients, apparent molar volumes, and apparent molar compressibilities were calculated from these data. Excess adiabatic compressibility properties were evaluated using volume fraction weighting of the individual component properties to estimate ideal mixture behavior. These results are compared with the data obtained based on the use of mole fraction weighting of the individual component properties for the ideal behavior value. A sharp ultrasonic velocity maximum and compressibility minimum is observed at low BE concentration in mixtures of water-BE at all temperatures. These maxima in ultrasonic velocity and minima in adiabatic compressibility are attributed to the formation of "clathrate-like" structures of water and alcohol. A shift of the velocity maximum towards lower concentrations of BE was observed with increase of temperature. A minimum in the ultrasonic velocity and a maximum in adiabatic compressibility coefficient values are observed in systems of BE-benzene and BE-decane. These results are discussed in terms of the breakdown of associated alcohol structures and the interstitial location of hydrocarbon molecules in alcohol aggregates. N. P. RAO et RONALD E. VERRALL. Can. J. Chem. 65, 810 (1987). OpCrant des tempkratures de 25, 40 et 55"C, on a mesurC les vitesses ultrasoniques et les densitCs des systemes binaires eau/butoxy-2 tthanol (BE), butoxy-2 Cthanollbenzkne et butoxy-2 CthanolldCcane. A partir de ces donnCes, on a calculC les coefficients de compressibilitC adiabatique, les volumes molaires apparents et les compressibilitCs molaires apparentes. Utilisant les poids relatifs des fractions du volume des propriCtCs des composantes individuelles pour Cvaluer le comportement du mClange idCal, on a CvaluC les propriCtCs de compressibilitC adiabatique en exces. On compare ces rCsultats avec les donnCes obtenues en se basant sur I'usage des poids relatifs des fractions molaires des propriCtCs des composantes individuelles pour Cvaluer le comportement du mClange ideal. A toutes les temperatures, on observe un maximum important de la vitesse ultrasonique et une compressibilitC minimale a des faibles concentrations de BE dans les mClanges eau/BE. On attribue ces maxima dans la vitesse ultrasonique et ces minima dans la compressibilitC adiabatique a la fom~ation de structures de l'eau et de llCthanol "ressernblant a des chlathrates". Lorsqu'on augmente la tempCrature, on observe un dCplacement du maximum de la vitesse vers les concentrations plus basses de BE. Dans les systemes BEIbenzkne et BEldCcane, on observe un minimum dans la vitesse ultrasonique et un maximum dans les valeurs des coefficients de compressibilitC adiabatique. On discute de ces rCsultats en fonction d'un bris des structures associCes de l'alcool et de la position des molCcules interstiti...

Section: Ultrasotlic Velocity Measurementsmentioning

confidence: 99%

Ultrasonic velocity, excess adiabatic compressibility, apparent molar volume, and apparent molar compressibility properties of binary liquid mixtures containing 2-butoxyethanol

Rao¹,

Verrall²

1987

“…Thus, a comparison of the method which has been described by various authors in the compressibilities of ions in non-aqueous and in literature (3)(4)(5). The ultrasonic pulse repetition rate (frequency) aqueous solvents should be very helpful in evaluat-was determined with a Nusonic Model 6105 solution monitor (Mapco Inc).…”

Section: Introductionmentioning

confidence: 99%

Isentropic compressibilities of electrolytes in acetonitrile at 25 °C

Davidson¹,

Perron²,

Desnoyers³

1981

. Can. J. Chem. 59,2212Chem. 59, (1981. The sound velocities of some I:1 electrolytes in acetonitrile were measured by the "sing around" method. Apparent molal isentropic compressibilities I$,, of the electrolytes were derived from these data and from previously determined densities. Infinite dilution partial molal compressibilities RsO were obtained by e x t r~p o l a t i o from the plot a~a i n s t the square-root of the molality. Approximate ionic values are obtained on the assumption that KsO (I$,B-) = 0. In general, KsO of inorganic ions are much more negative in acetonitrile than in water and, except for Li+, show little dependence on ionic size. On the other hand, RsO of tetraalkylammoniurn bromides become increasingly positive as the size of thecations increases. This is again incontrast with RsO of these electrolytes in water which remain negative. These large positive values arise from the free space between the ions and the solvent molecules, which is large in acetonitrile solutions.

“…The isentropic compressibility values ( K~) were obtained from speed-of-sound measurements at atmospheric pressure using a Nusonic instrument (Mapco, model 6105) (9). The working cell (20 cm3) was thermostated to *O.OOl°C and connected to a 250-cm3 reservoir; the latter served as a closed transfer and mass-dilution vessel for incremental composition changes.…”

Section: Methodsmentioning

confidence: 99%

“…[9] and [lo] were applied to the properties of the solvent mixtures to calculate the molar excess functions (c;,,,,) and (k:,,,,). The corresponding partial molar properties were also computed using the expressions (12): where a is the thermal expansibility coefficient.…”

Section: Methodsmentioning

confidence: 99%

A comprehensive thermodynamic investigation of water–ethanolamine mixtures at 10, 25, and 40 °C

Pagé¹,

Huot²,

Jolicoeur³

1993

. The density, isobaric specific heat capacity, and isentropic compressibility of water-ethanolamine (W-EA) mixtures have been measured at three temperatures (10, 25, and 40°C) over the entire composition range. The results were used to calculate various thermodynamic excess functions of these mixtures, namely: the excess molar volume (v:), excess molar isentropic and isothermal compressibilities ( K : . , , K:,,), excess molar isobaric and isochoric heat capacities (CF,,,,, CB,,,), and excess molar isobaric expansion (aVt/aT),. The corresponding partial molar quantities for ethanolamine in the mixtures were also computed. These excess and partial molar quantities were compared with those observed earlier in the water -ethylene glycol (W-EG) (1) and in the water-2-methoxyethanol (W-ME) (2) mixtures. The similarities and differences in the properties of these systems are interpreted on the basis of the specific molecular features of the cosolvents and the concepts of cooperative fluctuations and hydrogen-bonding connectivity in liquid water and dilute aqueous solutions. [Traduit par la redaction]