Vapor–liquid equilibrium,densities, and interfacial tensions for the system ethyl 1,1-dimethylethyl ether (ETBE) + propan-1-ol

Isobaric vapor–liquid equilibrium data at 50, 75, and 94 kPa have been determined for the binary system ETBE + propan-1-ol, in the temperature range 325–368 K. The measurements were made in a vapor–liquid equilibrium still with circulation of both phases. Mixing volumes have been also determined from density measurements at 298.15 K and 101.3 kPa and, at the same temperature and pressure, the dependence of interfacial tension on concentration has been measured using the pendant drop technique. According to experimental results, the mixture presents positive deviation from ideal behavior and azeotropy is present at 75 and 94 kPa. No azeotrope was detected at 50 kPa. The mixing volumes of the system are negative over the whole mole fraction range, and the interfacial tensions exhibit negative deviation from the linear behavior. The activity coefficients and boiling points of the solutions were well correlated with the mole fraction using the Wohl, Wilson, NRTL, UNIQUAC equations. Excess volume data and interfacial tensions were correlated using the Redlich–Kister model.     

Partial molar volumes and partial molar adiabatic compressibilities of a short chain perfluorosurfactant: Sodium heptafluorobutyrate in aqueous solutions at different temperatures

Density and ultrasound measurements of sodium heptafluorobutyrate in aqueous solutions at T = (283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K have been obtained. From these results partial molar volumes and isentropic partial molar adiabatic compressibilities were calculated. Deviations from the Debye-Hückel limiting law provide evidence for limited association at lower concentrations. The change of the partial molar volume and isentropic partial molar adiabatic compressibility upon aggregation was calculated. Variations of the change of partial molar volumes and isentropic partial molar adiabatic compressibility upon aggregation are discussed in terms of temperature.     

Excess molar volumes and viscosities of the ternary systemn-butylamine + 1,4-dioxane + acetonitrile at 25°C

Densities and viscosities for the n-butylamine + 1,4-dioxane + acetonitrile system were determined at 25°C and molar excess volumes and excess viscosities were calculated. Of the different expressions existing in the literature that predict these excess properties for ternary mixtures from data for the binary mixtures, the empirical correlation of Singh et al. is the best for this system.     

Volumetic Properties of Glycerol with N,N-Dimethylformamide and with Water at 25 and 35°C

Densities of glycerol + N,N-Dimethylformamide (DMF) and glycerol + water mixtures have been measured over the full range of compositions at 25 and 35°C. Excess molar volumes and excess partial molar volumes, of each system have been calculated. All mixtures show negative values of the excess molar volume due to increased interactions between unlike molecules.     

Acetonitrile + nitromethane: An example of ideal solvent mixtures

Densities, viscosities, static dielectric constants and refractive indices of acetonitrile + nitromethane mixtures in the temperature range between 5 and 45°C are reported. Density and viscosity data, analyzed in terms of molar excess volumes and molar excess fluidities, show a weak interactions field between acetonitrile and nitromethane molecules. Lorentz-Lorenz molar refractivities and Kirkwood correlation factors, obtained from refractive indices and dielectric constants data, respectively, indicate that such weak interactions can be atributed to an antiparallel alignment between neighboring dipoles of unlike solvent molecules. Such specific features do not significantly perturb the local structures of the pure components so that acetonitrile + nitromethane mixtures can be considered, in a first approximation, one of the few ideal solvent mixtures for which the physical properties can be determined by applying the additivity rules to the pure components.     

Some Thermodynamic Properties of the Binary Systems of Toluene with Butyl Methacrylate,Allyl Methacrylate,Methacrylic Acid and Vinyl Acetate at 20, 30 and 40 °C

Densities of the binary systems of toluene with butyl methacrylate, allyl methacrylate, methacrylic acid, and vinyl acetate have been measured as a function of composition at 20, 30 and 40 °C at atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The excess molar volumes are negative for the system toluene + butyl methacrylate and positive for the three other binaries, and become more so as the temperature increases from 20 to 40 °C. The system toluene + allyl methacrylate presents near ideal behavior. The apparent volumes were used to calculate values of the partial excess molar volumes at infinite dilution. The excess coefficient of thermal expansion is positive for the four binary systems. The calculated excess molar volumes were correlated with the Redlich–Kister equation and with a series of Legendre polynomials. An explanation of the results is given based by the FT-IR (ATR) and ¹³C NMR spectra of equimolar mixtures of the different systems.     

Density and Volumes of Mixing of the Ternary System Ethylbenzene + Styrene + Ethyl Acrylate and its Binaries at 298.15 K

Densities of the ternary system, ethylbenzene + styrene + ethyl acrylate, and its three binaries have been measured in the whole composition range at 298.15 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes are positive for the binary system, ethylbenzene + ethyl acrylate, and negative for the systems ethylbenzene + styrene and styrene + ethyl acrylate. The corresponding data were correlated with the Redlich-Kister equation and with a series of Legendre polynomials. Several models were used to correlate the ternary behavior from the excess molar volume data of their constituent binaries and were found to fit the data equally well. The best fit was based on a direct approach, without information on the component binary systems.     

Volumetric Properties of Aqueous Solutions of L-Glutamic Acid and Magnesium-L-Glutamate

Densities of aqueous solutions of L-glutamic acid and magnesium-L-glutamate were determined from T=288.15 to 333.15 K at 5 K temperature intervals. The measured densities were used to evaluate the apparent molar volumes, V _2,φ (m,T), the cubic expansion coefficients, α(m,T), and the changes of isobaric heat capacities with respect to pressure, (∂ C _p /∂ p) _T,m . They were qualitatively correlated with changes in the structure of water that occur when L-glutamic acid or magnesium-L-glutamate are present.     

On some ‘duality’ of the Nikodym property and the Hahn property

Drewnowski and Paúl proved in [L. Drewnowski, P.J. Paúl, The Nikodým property for ideals of sets defined by matrix summability methods, Rev. R. Acad. Cienc. Exactas Fís. Nat. (Esp.) 94 (2000) 485-503] that for any strongly nonatomic submeasure η on the power set P(N) of N the ideal Z(η)={N∈P(N)|η(N)=0} has the Nikodym property (NP); in particular, this result applies to densities dA defined by strongly regular matrices A. Grahame Bennett and the authors stated in [G. Bennett, J. Boos, T. Leiger, Sequences of 0's and 1's, Studia Math. 149 (2002) 75-99] that the strong null domain ₀|A| of any strongly regular matrix A has the Hahn property (HP). Moreover, Stuart and Abraham [C.E. Stuart, P. Abraham, Generalizations of the Nikodym boundedness and Vitali-Hahn-Saks theorems, J. Math. Anal. Appl. 300 (2) (2004) 351-361] pointed out that the said results are in some sense dual and that the last one follows from the first one by considering the density dA (defined by A) as submeasure on P(N) and the ideal Z(dA) as well by identifying P(N) with the set χ of sequences of 0's and 1's. In this paper we aim at a better understanding of the intimated duality and at a characterization of those members of special classes of matrices A such that Z(dA) has NP (equivalently, ₀|A| has HP).     

Acoustical and excess properties of {1-hexanol + n-hexane, or n-octane, or n-decane} at (298.15, 303.15, and 308.15) K

Densities (ρ) and speeds of sound (u) for the binary mixtures of 1-hexanol with n-hexane, n-octane and n-decane have been measured over the entire composition range at 298.15, 303.15 and 308.15 K. The dynamic viscosities (η) for these systems have been measured at 298.15 K. From experimental data, excess molar volumes (V_m^E), molar isentropic compressibility (K_s,m), excess molar isentropic compressibility (K_s,m^E), deviation in speed of sound (u^D) from their ideal values (u^id) in an ideal mixture, and excess free volumes (V_f^E) have been calculated. The excess functions have also been correlated with the Redlich–Kister polynomial equation. The viscosity data have been analysed in terms of some semi-empirical equations. The theoretical values of speed of sound (u) and isentropic compressibility (κ_S) have also been estimated using the Prigogine–Flory–Patterson (PFP) theory with the van der Waals (vdW) potential energy model and the results have been compared with experimental values. The effect of chain-length of n-alkanes as well as the temperature on the excess properties has also been studied.