Fully nonlinear ion-sound waves in a dense Fermi magnetoplasma

The nonlinear propagation of ion-sound waves in a collisionless dense electron-ion magnetoplasma is investigated. The inertialess electrons are assumed to follow a non-Boltzmann distribution due to the pressure for the Fermi plasma and the ions are described by the hydrodynamic (HD) equations. An energy balance-like equation involving a new Sagdeev-type pseudo-potential is derived in the presence of the quantum statistical effects. Numerical calculations reveal that the profiles of the Sagdeev-like potential and the ion-sound density excitations are significantly affected by the wave direction cosine and the Mach number. The present studies might be helpful to understand the excitation of nonlinear ion-sound waves in dense plasmas such as those in superdense white dwarfs and neutron stars as well as in intense laser-solid density plasma experiments.

Speeds of sound and isentropic compressibilities of binary mixtures containing trialkylamines with alkanes and mono-alkylamines at 303.15 and 313.15 K

Isentropic compressibilities ?S, and excess isentropic compressibilities ?SE have been determined from measurements of speeds of sound u and densities ? of 14 binary mixtures of triethylamine (TEA) and tri-n-butylamine (TBA) with n-hexane, n-octane, iso-octane, n-propylamine, n-butylamine, n-hexylamine and n-octylamine. The relative magnitude and sign of ?SE have been interpreted in terms of molecular interactions and interstitial accommodation. The values of ?SE for TEA + alkane are positive while for TBA + alkane are negative. The values of ?SE for TEA + primary amine become progressively less positive and eventually to negative with the increase in chain length of alkylamine. In case of TBA + primary amine, the values of ?SE increase from n-propylamine to n-butylamine, and then decrease with chain length of primary amine. The experimental speeds of sound u have been analyzed in terms of collision factor theory, free length theory and Prigogine–Flory–Patterson statistical theory of solutions.

Speeds of sound, isentropic compressibilities, and excess molar volumes of cycloalkanes, alkanes and aromatic hydrocarbons at 303.15 K. II. Results for cycloalkanes+aromatic hydrocarbons

The speeds of sound u, isentropic compressibilities ?S, molar sound functions R, excess isentropic compressibilities ?SE and excess molar volumes VE for eight binary mixtures of cyclopentane, cyclohexane, cyclooctane and methylcyclohexane with benzene and of cyclohexane with toluene, ethyl benzene, p-xylene and propyl benzene at 303.15 K are reported. The effects of molecular sizes and shapes of the component molecules and of interaction energy in the mixture have been discussed. The Prigogine–Flory–Patterson theory has been applied to analyze the present binary mixtures along with the mixtures of cis- and trans-decalins with benzene and toluene taken from the literature.

Densities, speeds of sound, isentropic compressibilities, refractive indices and viscosities of binary mixtures of tetrahydrofuran with hydrocarbons at 303.15 K

Isentropic compressibilities, Rao's molar sound functions, molar refractions, excess isentropic compressibilities, excess molar volumes, viscosity deviations and excess Gibbs energies of activation of viscous flow for seven binary mixtures of tetrahydrofuran (THF) with cyclohexane, methylcyclohexane, n-hexane, benzene, toluene, p-xylene and propylbenzene over the entire range of composition at 303.15 K have been derived from experimental densities, speeds of sound, refractive indices and viscosities. The excess partial molar volumes of THF in different solvents have been estimated. The experimental results have been analyzed in terms of the Prigogine–Flory–Patterson theory.

Densities, speeds of sound, isentropic compressibilities, refractive indexes, and viscosities of tetrahydrofuran with haloalkane or alkyl ethanoate at T = 303.15 K

Isentropic compressibilities ?S, excess isentropic compressibilities image, excess molar volumes VE, viscosity deviations ??, and excess Gibbs energy of activation of viscous flow ?G*E for nine binary mixtures of C4H8O with CCl4, CHCl3, CHCl2CHCl2, 1-C6H13Cl, 1-C6H13Br, CH3CO2CH3, CH3CO2C2H5, CH3CO2C4H9, and CH3CO2C5H11 at 303.15 K have been derived from experimental densities ?, speeds of sound u, refractive indexes nD and viscosities ?. The limiting values of excess partial molar volumes of C4H8O at infinite dilution image in different solvents have been estimated. The results obtained for dynamic viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg–Nissan, Tamura–Kurata, Hind–McLaughlin–Ubbelohde, Katti–Chaudhri, McAllister, Heric, and Auslaender. Finally, the experimental refractive indexes were compared with the predicted results for Lorentz–Lorenz, Dale–Gladstone, Eykman, Arago–Boit, Newton, Oster, Heller, and Wiener equations.

Speeds of sound, isentropic compressibilities, viscosities, and excess molar volumes of binary mixtures of alkanoates with tetra- and trichloromethanes at 303.15 K

Speeds of sound u, isentropic compressibilities ?S, viscosities ?, excess isentropic compressibilities ?SE, excess molar volumes VE, viscosity deviations ??, and excess Gibbs energies of activation ?G*E of viscous flow have been investigated for six binary mixtures of diethyl malonate, diethyl bromomalonate, and ethyl chloroacetate with tetra- and trichloromethane at 303.15 K. The values of ?SE, VE, ??, and ?G*E are highly dependent on the type of components involved and the composition curves are unsymmetrical. The results obtained for viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg-Nissan, Tamura-Kurata, Hind-McLaughlin-Ubbelohde, Katti-Chaudhri, McAllister, Heric-Brewer and Auslaender. The experimental speeds of sound have been analyzed in terms of collision factor theory and free length theory of solutions.

Thermodynamic Studies of Ionic Interactions in Aqueous Solutions of Imidazolium-Based Ionic Liquids [Emim][Br] and [Bmim][Cl]

Experimental measurements of density at different temperatures ranging from 293.15 to 313.15 K, the speed of sound and osmotic coefficients at 298.15 K for aqueous solution of 1-ethyl-3-methylimidazolium bromide ([Emim][Br]), and osmotic coefficients at 298.15 K for aqueous solutions of 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) in the dilute concentration region are taken. The data are used to obtain compressibilities, expansivity, apparent and limiting molar properties, internal pressure, activity, and activity coefficients for [Emim][Br] in aqueous solutions. Experimental activity coefficient data are compared with that obtained from Debye-Hückel and Pitzer models. The activity data are further used to obtain the hydration number and the osmotic second virial coefficients of ionic liquids. Partial molar entropies of [Bmim][Cl] are also obtained using the free-energy and enthalpy data. The distance of the closest approach of ions is estimated using the activity data for ILs in aqueous solutions and is compared with that of X-ray data analysis in the solid phase. The measured data show that the concentration dependence for aqueous solutions of [Emim][Br] can be accounted for in terms of the hydrophobic hydration of ions and that this IL exhibits Coulombic interactions as well as hydrophobic hydration for both the cations and anions. The small hydration numbers for the studied ILs indicate that the low charge density of cations and their hydrophobic nature is responsible for the formation of the water-structure-enforced ion pairs.

Acoustic and volumetric properties of aqueous solutions of imidazolium based ionic liquids at 298.15 K

The experimental measurements of the speed of sound and density of aqueous solutions of imidazolium based ionic liquids (IL) in the concentration range of 0.05 mol · kg-1 to 0.5 mol · kg-1 at T = 298.15 K are reported. The data are used to obtain the isentropic compressibility (ßS) of solutions. The apparent molar volume (phiV) and compressibility (phiKS) of ILs are evaluated at different concentrations. The data of limiting partial molar volume and compressibility of IL and their concentration variation are examined to evaluate the effect due to IL–water and IL–IL interactions. The results have been discussed in terms of hydrophobic hydration, hydrophobic interactions, and water structural changes in aqueous medium.