Search results for "Isentropic process"
showing 9 items of 9 documents
Volumes and compressibilities of pentanol in aqueous dodecyltrimethylammonium bromide solutions at 15, 25 and 35°C
1990
Ultrasonic velocities and densities of the water-dodecyltrimethylammonium bromide (DTAB)-pentanol (PentOH) ternary system were measured at 15, 25 and 35°C as a function of the surfactant and alcohol concentrations. The apparent molar volumes and isentropic compressibilities of PentOH were calculated. The standard partial molar volumes increase with surfactant concentration continuously whereas the standard partial molar isentropic compressibilities show sharp changes in slope at about 0.25 mol-kg−1 DTAB, which can be ascribed to a micellar structural transition. The volume data for alcohol in micellar solutions were treated by a model reported for the distribution of polar additives between…
Volumes and compressibilities of pentanol in aqueous alkyltrimethylammonium bromide solutions at different temperatures
1990
Speed of sound and density properties of ternary water-tetradecyltrimethylammonium bromide-pentanol system at 15, 25 and 35°C and of water-hexadecyltrimethylammonium bromide-pentanol system at 25, 35 and 45°C were measured at fixed alcohol concentration as a function of surfactant concentration. The apparent molar volumes Vϕ,R and isentropic compressibilities Kϕ,RS of pentanol in micellar solutions as a function of the surfactant concentration show irregular behavior which depends on the alkyl chain length of the surfactant and tends to disappear with increasing temperature. These anomalies are ascribed to micellar transitions. For both surfactants at high concentrations, Vϕ,R decrease and …
Anomalous Expansion of Attractively Interacting Fermionic Atoms in an Optical Lattice
2010
Strong correlations can dramatically modify the thermodynamics of a quantum many-particle system. Especially intriguing behaviour can appear when the system adiabatically enters a strongly correlated regime, for the interplay between entropy and strong interactions can lead to counterintuitive effects. A well known example is the so-called Pomeranchuk effect, occurring when liquid 3He is adiabatically compressed towards its crystalline phase. Here, we report on a novel anomalous, isentropic effect in a spin mixture of attractively interacting fermionic atoms in an optical lattice. As we adiabatically increase the attraction between the atoms we observe that the gas, instead of contracting, …
Thermophysical properties of binary mixtures of 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate ionic liquid with alcohols at several tempera…
2018
Abstract Densities, speeds of sound, and refractive indices for the binary systems made up by 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate and methanol, ethanol, 1-propanol, or 2-propanol, as well as for the pure components, have been measured covering the whole range of compositions at atmospheric pressure and T = (278.15–338.15) K. From densities and speeds of sound, isentropic compressibilities were calculated using the Newton-Laplace equation. Liquid ideal-mixture properties have been defined and calculated, and they have been used to determine excess molar volumes, excess isentropic compressibilities, and deviations in refractive indices. Excess and deviations in properties …
Volumetric and Ultrasonic Studies of 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate Ionic Liquid with Methanol, Ethanol, 1-Propanol, and Water…
2007
The speed of sound and density of mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with methanol, ethanol, 1-propanol, and water, as well as of the pure components have been experimentally measured over the whole range of compositions at T = (278.15 to 338.15) K and atmospheric pressure. From these experimental data, the excess molar volume, excess isentropic compressibility, and excess speed of sound have been calculated and fitted to an extended version of the Redlich−Kister equation, which takes into account the dependence on composition and temperature simultaneously. The Prigogine−Flory−Patterson theory has also been used to explain the behavior of t…
Density, Speed of Sound, and Refractive Index of 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate with Acetone, Methyl Acetate, and Ethyl Acetat…
2009
Densities, speeds of sound, and refractive indices of the binary mixtures of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][triflate]) with acetone, methyl acetate, and ethyl acetate were experimentally measured over the whole range of compositions at T = (278.15 to 328.15) K and a pressure of 0.1 MPa. From these experimental data, excess molar volumes, excess isentropic compressibilities, molar refractions, and deviations in refractive indices have been calculated and fitted to an extended version of the Redlich−Kister equation, which takes into account the dependence on composition and temperature simultaneously. The Prigogine−Flory−Patterson theory has been used to specula…
Partial molar volumes and compressibilities of alkyltrimethylammonium bromides
1990
Density and ultrasound measurements were performed for dodecyl- and tetradecyltrimethylammonium bromide at 15, 25 and 35°C and for hexadecyltrimethylammonium bromide at 25, 35 and 45°C over a wide concentration region. From these and previously reported data, partial molar volumes and isentropic and isothermal compressibilities were derived as a function of the surfactant concentration. It is shown that by increasing the surfactant concentration the apparent molar volumes and compressibilities increase according to the expected behavior of surfactant solutions. However, anomalies are displayed in plots of apparent molar compressibility of tetradecyltrimethylammonium bromide and of the speed…
Volumetric and Acoustic Properties of Aqueous Solutions of Trifluoromethanesulfonate-Based Ionic Liquids at Several Temperatures
2012
In this work, densities and sound velocities of three ionic liquids, 3-butyl-1-ethylimidazolium trifluoromethanesulfonate, 3-butyl-1-methylimidazolium trifluoromethanesulfonate, and 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, and their binary mixtures with water have been obtained at p = (101 ± 2) kPa and T = (278.15 to 338.15) K, covering the whole range of concentration. The isentropic compressibility and molar isentropic compression of pure components and mixtures have been calculated using the Newton–Laplace equation. Moreover, the excess molar volume and excess molar isentropic compression of mixtures have been then determined, and they have been fitted to temperature and …
Volumetric properties, viscosities and refractive indices of binary liquid mixtures of tetrafluoroborate-based ionic liquids with methanol at several…
2015
Abstract Densities, speeds of sound, viscosities and refractive indices of two binary systems 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] + methanol and 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF4] + methanol, as well as of all pure components, have been measured covering the whole range of compositions at T = (278.15 to 318.15) K and p = 101 kPa. From this data, excess molar volumes, excess isentropic compressibilities, viscosity deviations and refractive index deviations were calculated and fitted to extended versions of the Redlich–Kister equation. Estimated coefficients of these equations taking into account the dependence on composition and temperature simult…