Untersuchungen über das Verhalten organischer Mischphasen. 6. Mitteilung. Dampfdrücke,Dichten, thermodynamische Mischungsfunktionen und Brechungsindices des binären Systems Methanol-Diäthyl-äther bei 25°

The total vapor pressures, the heats of mixing, and the refractive indices of the system methanol-diethyl ether were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.     

Untersuchungen über das Verhalten organischer Mischphasen. 4. Mitteilung. Dampfdrücke,thermodynamische Mischungsfunktionen und Brechungsindizes der binären Systeme Tetrahydrofuran-Diäthyläther und Methanol-Tetrahydrofuran bei 25°

The total vapor pressure and the heats of mixing of the system tetrahydrofurane-diethyl ether, and methanol-tetrahydrofurane were measured at 25°C. The index of refraction was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, and entropy functions were calculated.     

Untersuchungen über das Verhalten organischer Mischphasen 8. Mitteilung. Dampfdrücke,Dichten, thermodynamische Mischungsfunktionen und Brechungsindices der binären Systeme Wasser-Tetrahydrofuran und Wasser-Diäthyläther bei 25°

The total vapor pressures and the heats of mixing of the water-tetrahydrofuran and water-diethyl ether systems were measured at 25°. Density, index of refraction, and KARL -FISCHER -titration were used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.     

Untersuchungen über das Verhalten organischer Mischphasen 7. Mitteilung. Dampfdrücke,Dichten und thermodynamische Mischungsfunktionen des binären Systems Cyclohexan- Tetrahydrofuran bei 25°

The total vapor pressures and the heats of mixing of the system cyclohexane-tetrahydrofuran were measured at 25°C. The density was used to determine concentrations for the total pressure measurements. The partial pressures, activity coefficients, excess free energies, entropy functions, and excess volumes were calculated.     

Intensitätsverhalten von Molekülanionen organischer Substanzen unter verschiedenen Versuchsbedingungen

A modified commercial mass spectrometer was used to perform quantitative measurements on negative ions of selected organic compounds at about 10^?4 Torr source pressure. The pressure dependency of the molecular ion intensity on pure compounds and binary mixtures shows up two different sources of slow secondary electrons. At low total source pressures a log-log plot of the ion intensity against the sample amount is linear and slow electrons are produced predominantly by wall effects, whereas at high pressures plasma effects arise with a non-linear pressure dependency.     

Zur Thermochemie der Halogensilane. VII1. Messung des Dampfdruckes über SiJ4,f und SiJ4,fl

The vapour pressures over SiJ₄,s and SiJ₄,l have been measured by the static and the flow method. The results were used to calculate the heat of evaporation, heat of sublimation, heat of fusion and standard entropy for SiJ₄.     

Beiträge zum chemischen Transport oxidischer Metallverbindungen. III. Der Transport von NiO und MgO über ihre Metallchloride

Transport effect of HCl on NiO and MgO according to between T₂ = 1000°C and T₁ = 800°C was calculated by the model of diffusion in dependence of total pressure; for comparison, the classical transport of α-Fe₂O₃ was analogously treated. By experimental determination of the transport rates at total pressures from 0.009 to 6 atm hitherto not considered influences of the amount and surface of the starting material, and of the transport time were found. These effects are explained by a (not in detail defined) term of ?sorption”? of the transport gas onto the powder of the starting material. For an explanation of the transport rates estimations of the diffusion coefficients of the gas pairs FeCl₃–HCl and NiCl₂–HCl were performed and the vapour pressure diagrams of NiCl₂ and MgCl₂ evaluated.     

Adsorption phenomena at high pressures and temperatures 4. Isotherms of excess and absolute adsorption of Kr on NaA zeolite

The problem of conversion of an isotherm of excess adsorption measured experimentally into values of the total amount of the adsorbate (absolute adsorption) has been formulated. Five isotherms of excess adsorption of krypton on NaA zeolite were measured (at 334–500 K) at equilibrium pressures of -160 MPa. The corresponding isotherms of the total amount were calculated and the temperature dependences of the parameters of an equation describing the isotherms of excess adsorption were identified. It was shown that at high temperatures and pressures, krypton atoms diffuse into the -cavities of the NaA zeolite.For Part 3, seeRuss. Chem. Bull., 1996, 45, 534 (Engl. Transl.).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1138–1142, May, 1996.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. I. Sättigungsdruck und Bildungsenthalpie von MoO2Br2 und MoO2CI2

Molybdenum dioxiddibromide and -dichloride have been prepared from MoO₂, Br₂, und Cl₂, respectively, and their chemical and thermochemival behaviour was studied. Their enthalpies of formation, ΔH°, have been determined from the solution enthalpies of MoO₂Br₂, and MOo₂Cl₂, in aqueous NaOH (data see ?Inhaltsübersicht”?). From their sublimation pressures, p, the enthalpies, ΔH° (subl.), and entropies, ΔS° (subl.), of sublimation have been evaluated (data see above).     

K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-KCl-H<Subscript>2</Subscript>O phase diagram in the area of heterogenization of homogeneous supercritical fluids

The experimental investigations of phase equilibria in the K₂SO₄-KCl-H₂O system at temperatures to 500°C and pressures to 100 MPa were directed to elucidate the phase transformation sequence that leads to the heterogenization of the supercritical fluid whose existence field propagates from the K₂SO₄-H₂O binary subsystem to the ternary system. We suggest that fluid heterogenization in the title ternary system is accompanied by the transformation of the metastable immiscibility field to stable equilibria at elevated temperatures (near 460°C) and unexpectedly high pressures (～60 MPa), despite the presence of a vapor phase.     

Dampfdruckmessungen an einigen binären Systemen Seltenerdchlorid–Alkalichlorid

The partial pressures of alkali chloride and magnesium chloride have been determined over molten mixtures with rare earth chloride in the systems CsCl? NdCl₃, CsCl? SmCl₃, KCl? NdCl₃, LiCl? NdCl₃, MgCl₂? NdCl₃. The experimental results were used to calculate the activities of the components and the integral free enthalpy of mixing. The negative deviations from ideal behaviour increase in the series MgCl₂, LiCl, KCl, CsCl. The qualitative composition of the vapour phase was analyzed by a mass-spectrometer.     

ChemInform Abstract: Pressure‐Induced Phase Transition of SnH4: A New Layered Structure.

A new phase of SnH₄ with C2/m symmetry is predicted by first‐principle calculations using the Vienne ab initio simulation package (VSAP code) at pressures <400 GPa.     

Thermochemische Untersuchungen zum quasibinären System YbOCl/SeO2

Thermochemical Investigations on the Pseudobinary System YbOCl/SeO₂ On the pseudobinary section YbOCl/SeO₂ four thermodynamically stable compounds exist in accordance with the thermal decomposition and the phase analysis of defined powder mixtures: YbOCl · 3 SeO₂ = YbSe₃O₇Cl, YbOCl · 2 SeO₂ = YbSe₂O₅Cl and YbOCl · SeO₂ = YbSeO₃Cl as well as the YbOCl‐rich phase Yb₂SeO₄Cl₂ (2 YbOCl · SeO₂). The phase barogram and the phase diagram of the pseudobinary section YbOCl/SeO₂ were set up by total pressure measurements and DTA. From the temperature dependence of the decomposition pressures the enthalpies of formation and the standard entropies of the phases were deduced. In addition, the enthalpies of formation of the new compounds were determined from the enthalpies of solution of YbOCl, SeO₂ and the quaternary phases.     

Methane and carbon dioxide solubility in 1,2-propylene glycol at temperatures ranging from 303 to 423 K and pressures up to 12 MPa

This work reports solubility data of methane and carbon dioxide in 1,2-propylene glycol and the Henry's law constant of each solute in the studied solvent at saturation pressure. The measurements were performed at 303, 323, 373, 398 and 423.15 K and pressures up to 4.5 MPa for carbon dioxide solubility and pressures up to 12.1 MPa for methane solubility. The experiments were performed in an autoclave type phase equilibrium apparatus using the total pressure method (synthetic method). All investigated systems show an increase of gas-solubility with the increase of pressure. A decrease of carbon dioxide solubility with the increase of temperature and an increase of methane solubility with the increase of temperature was observed. From the variation of solubility with temperature, partial molar enthalpy and entropy change of the solute for each mixture were calculated.     

Determination of evaporation rates and vapor pressures of very low volatility compounds: a study of the C4-C10 and C12 dicarboxylic acids

A method for the measurement of evaporation rates and vapor pressures of low volatility compounds was developed and applied to the homologous series of C4-C10 and C12 dicarboxylic acids. Proton-transfer chemical ionization mass spectrometry was used to follow directly the temperature-dependent evaporation rates of aerosol samples collected on a cold plate that could be heated at a known rate. The vapor pressures of the deposited compounds were derived from observed evaporation rates through application of the Hertz-Knudsen equation. Temperature programmed desorption allowed for quantification of the enthalpy (DeltaHsub) and entropy (DeltaSsub) of sublimation of the diacids and is described. A strong odd-even dependence with respect to the total carbon number was observed in the derived diacid vapor pressures, consistent with previous measurements. However, the vapor pressures from this method were systematically lower than previous measurements. Though seen in the vapor pressure, no odd-even carbon chain length dependence was readily discernible in the measured values of DeltaHsub and DeltaSsub. Perhaps most importantly, these experimental results also suggest that residual solvent molecules (from the aerosol generation process) trapped in the diacid samples can have a considerable influence on the measured thermodynamic parameters and, if not properly accounted for, may give erroneous results.     

Partial molar volumes of organic solutes in water. XV. Butanediols(aq) at temperatures from (298 K to 573 K) and at pressures up to 30 MPa

Density data for dilute aqueous solutions of three butanediols (1,3-butanediol, 2,3-butanediol, 1,4-butanediol) are presented together with partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from 298.15 K up to 573.15 K and at pressures close to the saturated vapour pressure of water, at pressures close to 20 MPa and 30 MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter.     

Negative ion clusters in self-condensation of GeH4.

Formation of negative ion clusters from GeH4 has been studied as a function of germane pressure, in the 25-450 mTorr range, by chemical ionisation mass spectrometry. At the lowest pressures, only the GeHn- (n = 0-3) ion family is formed, whilst at increasing pressures GemHn- (m = 1-9) ion clusters of increasing size are observed in the mass spectra. A variable contribution of the ions with different hydrogen content is observed as a function of the pressure of germane in all the GemHn- (m = 1-9) clusters. Increasing pressures induce a general increase of ion species with a low content of hydrogen atoms. In fact, at 450 mTorr, 38% of the ion current is due to the bare Gem- (m = 2-5) clusters and 83% to the sum of abundances of the GemHn- ions without hydrogen (n = 0) and with a number of hydrogen atoms not higher than the number of germanium atoms (n = 0-m). This trend suggests that a contribution of negative clusters to the deposition of the amorphous solid a-Ge:H from gaseous systems containing GeH4, activated by radiolytic methods, can enhance the formation of solids with a low hydrogen content, which show better photoelectrical properties.     

Die Bestimmung der Bildungsenthalpie von RhI3,s mit Hilfe einer weiterentwickelten Wägemethode zur Messung temperaturabhängiger Partialdrücke in geschlossenen Systemen

Determination of Temperature Dependent Partial Pressures in Closed Systems. A New Improved Method. The Heat of Formation of RhI_3,s An improved method to determine temperature dependent partial pressures of gaseous species in equilibria with condensed phases in closed systems (silica ampoules) at temperatures up to 1000 °C and pressures p_i 0.1 < p_i < 15 bar is presented. The method is based on the determination of the change of mass in the gasphase caused by solid gas transition at higher temperatures concerning substances which are deposited at one end of the ampoule. The results of the measurements give informations about reaction mechanisms, and enthalpies. The reliability of the method is demonstrated at the example of the heat of formation of RhI_3,s (δ_BH°(RhI_3,s, 298) = –142.2 kJ · mol^–1).     

Massenspektrometrische Untersuchungen binärer Mischungen aus Alkalimetall- und Erdalkalimetallhalogeniden

Mass Spectrometrical Investigations of Binary Mixtures Alkali Halide – Alkaline Earth Halide The vapor composition of some binary mixtures alkali halide – alkaline earth halide was investigated by high-temperature mass spectrometry. Concentrations of all molecules in gas phase in dependence on the molar composition of liquid mixture were studied. In the vapors over all mixtures exist gaseous heterocomplexes. With increasing radius of the anion a tendency of decreasing stabilities of 1:1 heterocomplexes is stated. The absolute content of gaseous complexes is a function of the ratio of the vapor pressures of the pure components of mixtures. Calculated formation enthalpies fo various stoichiometric heterocomplexes are given.     

Molecular Mechanisms of the Effect of Water on CO<Subscript>2</Subscript>/CH<Subscript>4</Subscript> Mixture Adsorption in Slitlike Carbon Pores

The grand canonical ensemble Monte Carlo method has been used to study adsorption of carbon dioxide, methane, and their mixtures with different compositions in slitlike carbon pores at a temperature of 318 K and pressures below 60 atm. The data obtained have been used to show the effect of fixed amounts of pre-adsorbed water (19, 37, and 70 vol %) on the adsorption capacity and selectivity of carbon micro- and mesopores. The presence of water reduces the adsorption capacity throughout the studied pressure range upon adsorption of gaseous mixtures containing less than 50% CO₂, as well as in narrow micropores (with widths of 8?12 Å). Upon adsorption of mixtures with CO₂ contents higher than 50%, the adsorption capacity of pores with low water contents appears, in some region of the isotherm, to be higher than that in dry pores. In the case of wide pores (16 and 20 Å), this region is located at low and moderate pressures, while for mesopores it is located at high pressures. The analysis of the calculated data has shown that the molecular mechanism of the influence of preadsorbed water on the adsorption capacity is based on the competition between the volume accessible for adsorption (decreases the capacity) and the strength of the interaction between carbon dioxide molecules and water molecules (increases the capacity). Therewith, the larger the surface area of the water–gas contact, the stronger the H₂O–CO₂ interactions.