Pseudo-binary Mixtures Research Articles

Acidity of hyperconcentrated electrolyte solutions. Hammett acidity function measurements for aqueous ZnCl2, + LiCl solutions

The Hammett acidity function has been evaluated by means of spectrophotometric measurements with thymol blue indicator for (1-x)(ZnCl2,RH2O)+x(LiCl,RH2O) pseudobinary mixtures where R is 4 and 6. The pseudobinary mixtures have well defined minimum acidity near the composition (x = 0.67) which corresponds to the tetrachlorozincate ion stoichiometry. The acidity data for these mixtures support the conclusion that the properties of mixtures with R ≤ 6 are dominated by formation of tetrachlorozincate anions.

The metal-semiconductor transition in thallium-rich liquid Tl-Te alloys

Abstract Evidence that liquid T1xTe1-x alloys in the composition range ⅔ > × > 1 are pseudobinary mixtures Tl+Tl2Te prompts the examination of the implications of this molecular structure for the change in the electronic structure as the composition is changed continuously from a typical metal T1 to a typical liquid semiconductor T12Te. By ignoring the mixing of states, a first approximation is derived from a superposition of tight-binding bands due to the two constituents T1 and T12Te. The relative energies of the bands due to the two constituents are strongly affected by charge transfer between them. When the semiconductor constituent has a small band gap and a large high-frequency dielectric constant as in T12Te, the conduction-band edge of the semiconductor drops below the Fermi energy when the metal concentration is still large. This is in contrast to the case of a metal dissolved in a wide band gap semiconductor such as argon, where the conduction band of the metal simply narrows and becomes an impurity band within the argon band gap, as suggested by the pseudogap model. The effects of mixing of states between bands are considered qualitatively. Experimental data for T1-Te alloys are discussed which indicate that the transition between the two kinds of conduction band (T1 and T12Te) occurs at ≅0.8.

Eutectic crystallization of pseudo binary systems of polyethylene and high melting diluents

The crystallization and melting behaviour of the pseudo binary systems of heterodisperse polyethylene and the high melting diluents 1,2,4,5-tetrachlorobenzene and hexamethyl-benzene have been studied by differential scanning calorimetry and microscopy. Using the Flory-Huggins theory the equilibrium phase diagram of polyethylene/1,2,4,5-tetrachlorobenzene was calculated for χ=0.37, which gave a eutectic temperature of 135°C for a polyethylene volume fraction of 0.51. The experimentally determined eutectic points were found to depend strongly on the crystallization circumstances; the lowest value for the eutectic temperature for the system polyethylene/1,2,4,5-tetrachlorobenzene was 106°C. A large degree of supercooling was required for the eutectic crystallization, indicating that the nucleation of the low molecular components is markedly hampered by the polymer molecules. If only crystals of the diluent are formed the morphology is needlelike. A spherulitic texture develops under eutectic conditions. By sublimation of the solid diluent from the pseudo binary mixtures a cellular polymeric material of a unique texture and morphology is produced.

The Acetone – Acetic Anhydride – Carbon Disulfide System: Surface Tension, Viscosity, and Total and Partial Vapor Pressures

The surface tensions, viscosities, and vapor pressures, total and partial, have been determined as functions of concentration for the following systems: (a) acetone – acetic anhydride; (b) acetone – carbon disulfide; (c) acetic anhydride – carbon disulfide; and (d) pseudo-binary mixtures of (a) and (b), whose compositions lie on a straight line tangential to the plait point of the ternary system.The general behavior of ideal and non-ideal systems, in regard to surface tension and viscosity is discussed. For the system acetone – carbon disulfide, whose vapor phase can be considered ideal, the activities, activity coefficients, excess free energies, enthalpies and entropies of mixing have been obtained from the vapor pressures. The vapor phase of the other three systems contains acetic anhydride which is associated in the vapor state, and for these systems the experimental data are reported without further calculation.

Upper limit of the complex formation of normal C6-C17 alkanes in multicomponent mixtures

1. It has been shown that from the point of view of the theory of the upper limit of complex formation, n-hexane can be the main component only of binary or pseudobinary mixtures, but not of multicomponent mixtures. 2. Empirical dependences have been found for the change in the temperature of the upper limit of complex formation of n-heptane and of C10-C17 n-alkanes in multicomponent mixtures on the change in the partial concentrations of the other components. 3. By analogy with previously advanced concepts with respect to the two forms of the dependence θ=f (n) [4], it is postulated that, for multicornponent mixtures, Eq. (1) is of a partial character, while Eq. (2) is more universal and can be used in applied form for the separation of n-alkanes with n ≥ 10 from petroleum fractions.

An ultrasonic interferometer for the acoustic analysis of gas mixtures

It is suggested that many binary or pseudo-binary gas mixtures may be analysed by measuring their acoustic velocities. The construction and operation of an ultrasonic interferometer and its application to the analysis of gas mixtures are described, and a possible pulse method is discussed.

Heliodyne: A minimal solar-powered interplanetary vehicle : Benedikt, E. T., R. W. Halliburton, and C. C. Kelber, Astro Systems and Research Laboratories, September 1960, 28 p., Illus.

The surface of beeswax seals shows a tendency to become covered with a white crystallic layer, composed mainly of unsaturated hydrocarbons. In order to obtain deeper insight into the nature of this adverse phenomenon, the thermal properties of the efflorescence and the pseudobinary mixtures efflorescence/beeswax were studied employing DSC and FTIR methods. The results are in agreement with the hypothesis that a primary cause of the problem is the limited miscibility of both pseudocomponents. Although a certain amount of alkenes can be “tolerated” in recrystallized beeswax, the resulting mixture is metastable. The possible delayed crystallization of alkenes is then connected with the development of the efflorescence. An understanding of the problem is important for suggesting reasonable conservation measures.