Search results for "Molar volume"
showing 10 items of 55 documents
Demixing of Mixed Micelles. Thermodynamics of Sodium Perfluorooctanoate−Sodium Dodecanoate Mixtures in Water
1997
Conductivity, density, heat capacity, enthalpy of dilution, and osmotic coefficient measurements of water−sodium perfluorooctanoate (NaPFO)−sodium dodecanoate systems were carried out as functions of the surfactants' total molality (mt) at different mole fractions (XNaPFO). From conductivity data, the critical micelle concentration (cmc) and the degree of ionization (β) of the micelles were derived. The cmc's of the micelles are higher than those of the pure surfactants while β depends linearly on XNaPFO. At a given mole fraction, the apparent molar volume (VΦ) and heat capacity (CΦ) of the mixture increases and decreases monotonically with mt, respectively. From data in the premicellar reg…
Apparent Molar Volumes of Calcium Nitrate in 1-Propanol + Water at 298.15 K
1999
The densities of 1-propanol + water + calcium nitrate mixtures have been measured with an oscillating-tube densimeter over a large range of concentrations of the salt and 1-propanol, at 298.15 K. From these densities, apparent molar volumes of calcium nitrate in 1-propanol + water mixtures have been calculated, and partial molar volumes at infinite dilution have been evaluated.
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 …
Apparent molar volumes of strontium chloride in ethanol + water at 298.15 K
1997
Densities of ethanol + water + strontium chloride mixtures have been measured with an oscillating-tube densimeter over a large range of concentrations of the salt and ethanol, at 298.15 K. From these densities, apparent molar volumes of the electrolyte in these mixtures have been calculated, and partial molar volumes at infinite dilution have been evaluated.
Pressure-induced structural evaluation and insulator-metal transition in the mixed spinel ferrite Zn0.2Mg0.8Fe2O4
2017
The effect of pressure on the electronic properties and crystal structure in a mixed spinel ferrite $\mathrm{Z}{\mathrm{n}}_{0.2}\mathrm{M}{\mathrm{g}}_{0.8}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{O}}_{4}$ was studied for the first time up to 48 GPa at room temperature using x-ray diffraction, Raman spectroscopy, and electrical transport measurements. The sample was cubic (spinel-type $Fd\overline{3}m$) at ambient pressure and underwent a pressure-induced structural transition to an orthorhombic phase $(\mathrm{CaT}{\mathrm{i}}_{2}{\mathrm{O}}_{4}\ensuremath{-}\mathrm{type}\phantom{\rule{0.16em}{0ex}}Bbmm)$ at 21 GPa. This structural transformation corresponded to a first-order phase transition …
Calorimetric and Volumetric Investigations of the Effect of the Hydrophobicity of the Surfactant on the Binding between (Ethylene oxide)13-(propylene…
2004
The enthalpy and the volume of transfer (DeltaY(t)) of the unassociated (ethylene oxide)(13)-(propylene oxide)(30)-(ethylene oxide)(13) (L64) from water to the aqueous sodium alkanoate solutions as functions of the surfactant concentrations (m(S)) were determined at 298 K. The surfactants studied are sodium hexanoate, sodium heptanoate, sodium octanoate, sodium undecanoate, and sodium dodecanoate. As a general feature, for the short alkyl chain surfactants, DeltaY(t) describes an S-shaped curve in the range of m(S) analyzed whereas for the more hydrophobic surfactants the DeltaY(t) vs m(S) trends exhibit maxima which appear at ms values very close to the critical micellar concentration in w…
Potential of human serum albumin as chiral selector of basic drugs in affinity electrokinetic chromatography-partial filling technique
2006
The enantiomeric resolution of compounds using HSA by means of affinity EKC (AEKC)-partial filling technique is the result of a delicate balance between different experimental variables such as protein concentration, running pH (background electrophoretic buffer (BGE), protein, and compound solutions), and plug length. In this paper, the possibility of using HSA as chiral selector for enantioseparation of 28 basic drugs using this methodology is studied. The effect of the physicochemical parameters, the structural properties of compounds, and compound-HSA protein binding percentages over their chiral resolution with HSA is outlined. Based on the results obtained, a decision tree is proposed…
Densities, Refractive Indices, and Excess Molar Volumes of Binary and Ternary Systems Containing Isobutyl Alcohol, Ethanol, 2-Methylpentane, and Meth…
2000
This paper reports experimental densities and refractive indices of binary and ternary systems containing isobutyl alcohol, ethanol, 2-methylpentane, and methyl tert-butyl ether over the whole composition range of mixtures at 298.15 K and atmospheric pressure. From these data, excess molar volumes VE have been calculated. These results are fitted to the Redlich−Kister and Cibulka polynomial equations to derive the binary and ternary coefficients, respectively.
Standard partial molar volumes of alcohols in aqueous dodecyltrimethylammonium bromide solutions
1990
Density measurements of water-dodecyltrimethylammonium bromide (DTAB)-alcohol ternary systems as a function of alcohol and surfactant concentrations were carried out at 25°C. The alcohols were propanol (PrOH), 2-propanol (2-PrOH) and hexanol (HexOH). The apparent molar volume Vϕ,R of alcohols have been calculated and the standard (infinite dilution) partial molar volumes of alcohols V R at each surfactant concentration were obtained by means of a least squares fit of Vϕ,R vs. the alcohol concentration. The V R vs. surfactant concentration curves have been rationalized in terms of the partial molar volume of alcohol in the aqueous V f and the micellar V b phases and the distribution constant…