Solubility of Solid 2,3-Dimethylbutane and Cyclopentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 2,3-dimethylbutane and cyclopentene in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in solutes. The experimental value of the mole fraction solubility of solid 2,3-dimethyl-butane in liquid argon at 87.3 K is (8.26 ± 1.60) × 10^–6 and (2.77 ± 0.94) × 10^–8 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid cyclopentene in liquid argon at 87.3 K is (5.11 ± 0.44) × 10^–6 and (4.60 ± 0.76) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for investigated solid hydrocarbons than is liquid nitrogen.     

Solubility of Solid 1-Hexyne in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 1-hexyne in liquid argon at 87.3 and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in 1-hexyne. The experimental value of the mole fraction solubility of solid 1-hexyne in liquid argon at 87.3 K is (0.85 ± 0.19) × 10^–7 and (1.25 ± 0.08) × 10^–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for solid 1-hexyne than is liquid nitrogen.     

Solubility of Solid 2-Methyl-1,3-butadiene (Isoprene) in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubility of solid 2-methyl-1,3-butadiene (isoprene) in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K has been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in the solute. The experimental value of the mole fraction solubility of solid isoprene in liquid argon at 87.3 K is (1.41 ± 0.27) × 10^–6 and (1.56 ± 0.36) × 10^–7 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbon in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l ₁₂ were also calculated. At 90.0 K liquid argon is a better solvent for isoprene than is liquid nitrogen. The experimental values of the solubilities of isoprene in liquid argon and nitrogen were compared with results obtained for selected unsaturated and aromatic hydrocarbons.     

Solubility of Solid 1-Hexene and 2-Methylpentane in Liquid Argon and Nitrogen at the Standard Boiling Points of the Solvents

The solubilities of solid 1-hexene and 2-methylpentane in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. The experimental value of the mole fraction solubility of solid 1-hexene in liquid argon at 87.3 K is (3.87 ± 0.74) × 10^-7 and (7.94 ± 2.47) × 10^-9 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid 2-methylpentane in liquid argon at 87.3 K is (1.45 ± 0.36) × 10^-5 and (6.80 ± 2.16) × 10^-8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters 1₁₂ were also calculated. At 90.0 K, liquid argon is a better solvent for solid 1-hexene and 2-methylpentane than is liquid nitrogen.     

Solubility of Solid Hexane and Cyclohexane in Liquid Argon at 87.3 K

The solubilities of solid hexane and cyclohexane in liquid argon at 87.3 K have been measured by the filtration method. The hexane and cyclohexane content in solution was determined using gas chromatography. The solubilities of the C₆ hydrocarbons in liquid argon at 87.3 K are (0.56 ± 0.11) × 10^-7 mole fraction for hexane and (1.04 ± 0.30) × 10^-7 mole fraction for cyclohexane. The Preston–Prausnitz method was used for calculation of the solubilities of solid hexane and cyclohexane in liquid argon in the temperature range 84–110 K. The values of the solvent–solute interaction constant l₁₂ were also calculated.     

Solubility of Solid Pentane, 2-Methylbutane, and Cyclopentane in Liquid Argon at 87.3 K

The solubilities of solid pentane, 2-methylbutane (isopentane), and cyclopentane in liquid argon at 87.3 K have been measured by the filtration method. The C₅ hydrocarbon content in solution was determined using gas chromatography. The solubilities of the C₅ hydrocarbons in liquid argon at 87.3K vary from 0.61 × 10^–7 mole fraction for cyclopentane, to 1.37 × 10^–7 mole fraction for pentane, and 8.83 × 10^–6 mole fraction for 2-methylbutane. The Preston–Prausnitz method was used for calculation of the solubilities of solid C₅ hydrocarbons in liquid argon in the temperature range 84–110 K and in liquid nitrogen in the range 64–90K. The values of the solvent–solute interaction constant l ₁₂ were also calculated.     

Solubility of pentane, 2-methylbutane,and cyclopentane in liquid nitrogen at 77.4 K

The solubilities of pentane, 2-methylbutane (isopentane) and cyclopentane were measured in liquid nitrogen at 77.4 K by the filtration method. The solubilities of the C₅ hydrocarbons in liquid nitrogen at 77.4 K vary from 1.8×10^–8 mole fraction for cyclopentane, to 3.0×10^–8 mole fraction for pentane and 3.2×10^–7 mole fraction for 2-metylbutane. Correlations between the solubilities of alkanes, alkenes and cyclic hydrocarbons in liquid nitrogen, and some properties of solutes [normal boiling point T _b , enthalpy of vaporization at normal boiling point H _b and the mean of the enthalpy of vaporization and the enthalpy of melting [(H _b +H _m )/2] are presented.     

Measuring the solubilities of ionic liquids in water using ion-selective electrodes

Polyvinyl chloride-plasticized membrane ion-selective electrodes (ISE) based on conventional ion-exchangers have been proposed as a cheap universal tool to measure the solubilities of ionic liquids (ILs) in water. They are applicable for ILs with a wide range of solubilities in water, since the linear range of a potentiometric response spans several orders of magnitude. As an example, we have fabricated and tested ISEs for widely used alkylimidazolium ionic liquids. The aqueous solubilities of four typical ILs have been determined at 21 °C: 0.075±0.001 mol l^–1 (1-butyl-3-methylimidazolium, BMIm, hexafluorophosphate); 0.018±0.001 mol l^–1 (BMIm bis(triflylimide)); 0.054±0.007 mol l^–1 (1-butyl-2,3-dimethylimidazolium, BDMIm, hexafluorophosphate); 0.014±0.001 mol l^–1 (BDMIm bis(triflylimide)).     

The solubilities of nitrous oxide,carbon dioxide,Aliphatic ethers and alcohols,and water in cryogenic liquids

Experimental investigations using IR spectroscopy and a variable pressure cell (up to 30 bar) have shown that nitrous oxide, carbon dioxide and some aliphatic ethers are considerably soluble in liquid nitrogen, liquid oxygen and liquid argon between 77 K and 135 K, with solubilities ranging from 10⁻⁴ mole fraction for nitrous oxide to 10⁻⁸ mole fraction for di-isopropyl ether. The solubility data have been found to be dependent on the temperature of the cryogenic liquid and the molecular structures and properties of the solute and solvent molecules. The solubilities of water, hydrogen sulphide, methanol and ethanol have been found experimentally to be very low, i.e. less than 10⁻⁸ mole fraction in liquid nitrogen, liquid oxygen and liquid argon. These values are considerably lower than those measured previously using gravimetric methods (10⁻⁷ - 10⁻⁵). The experimental solubilities are compared with the predicted values based on the “ideal” and “regular solution” theories. Both theories failed to predict solubilities comparable with the experimental values.     

Aqueous solubilities and enthalpies of solution of adenine and guanine

A generator column—liquid chromatographic technique was used to determine the aqueous solubility of adenine from 20 to 30°C, and of guanine from 15 to 40°C. The 95% confidence limits of the solubilities and molar enthalpies of solution at 25°C are: 8.7±0.1×10^–3M and 33.5±0.5 kJ-mol^–1 for adenine; 3.9±0.1×10^–5M and 49.2±0.6 kJ-mol^–1 for guanine. the adenine enthalpy value includes a small correction for association in the saturated solutions. The previously undetermined molar enthalpy of the second ionization step of guanine (to form the doubly-charged guanine anion) is estimated from our data combined with other measurements to equal 33.8±2.9 kJ-mol^–1.     

DSC study of YaBabCucO72212;δ homogeneity in the region 1050–1300 K

Phase transitions of the compositions Y_1±xBa_2±yCu_3±zO_72212; (x,y=0–0.2;z=0–0.5; step 0.1) were studied by DSC in argon atmosphere in the temperature range 1050–1300 K. The formation of three polymorphous modifications of the 123 phase was observed. The solubilities of yttrium, barium and copper oxides in every modification were determined. TheT-x-y phase microdiagram for the 123 phase was mapped out.     

Pressure Dependence of the Solubilities of Anthracene and Phenanthrene in Water at 25°C

Solubilities of anthracene and phenanthrene in water were measured at 298.15K at pressures to 200 MPa and were found to decrease with increasing pressure.From the pressure coefficients of the solubilities, the volume changesaccompanying the dissolution were estimated to be 15.1±0.6 cm³-mol–1 for anthraceneand 12.4±0.3 cm³-mol–1 for phenanthrene. The partial molar volumes of thesesolutes in water are presumed to decrease with increasing pressure, contrary to thenegative compressibility of alkylbenzenes previously observed in water. Volumechanges accompanying hydrophobic hydration are also estimated to be 1.4cm³-mol–1 for anthracene and 4.1 cm³-mol–1 for phenanthrene, respectively. Thesepositive values are opposite to the negative ones usually observed for hydrophobichydration. The hydration structure of these hydrocarbons is discussed.     

Low-pressure solubilities and thermodynamics of solvation of eight gases in 1-butyl-3-methylimidazolium hexafluorophosphate

Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF₆] – a room temperature ionic liquid – are reported as a function of temperature between 283 and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble and hydrogen is the least soluble of the gases studied with mole fraction solubilities of the order of 10⁻² and 10⁻⁴, respectively. All the mole fraction solubilities decrease with temperature except for hydrogen for which a maximum is observed at temperatures close to 310 K. From the variation of solubility, expressed as Henry's law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry's law constants from appropriate smoothing equations, is better than ±1%.     

Temperature and density profiles of magnetically rotating arcs burning in contaminated argon

Spectroscopic measurements on copper vapors emitted by the cathode are presented for magnetically rotating arcs in a coaxial copper electrode geometry. The maximum temperature of a 100-A arc column burning in contaminated argon is shown to be lower than 8000 K. A maximum Cu density of 5 × 10²¹ in m^–3 is observed when argon is contaminated with 1% CO, while it is larger than 10²² m^–3 with 1% nitrogen contamination. The copper vapors emitted by the cathode explain the low temperatures observed. Cases of surface control of the arc velocity at the cathode and radial losses of copper vapors out of the arc column are observed front specific parameters describing the arc profiles. Evidence is given for a copper ion recombination zone extending 2 mm from the cathode in the nitrogen contamination case.     

Solubility of carbon dioxide,ethane, methane,oxygen, nitrogen,hydrogen, argon,and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate between temperatures 283 K and 343 K and at pressures close to atmospheric

Experimental values for the solubility of carbon dioxide, ethane, methane, oxygen, nitrogen, hydrogen, argon and carbon monoxide in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF₄] – a room temperature ionic liquid – are reported as a function of temperature between 283 K and 343 K and at pressures close to atmospheric. Carbon dioxide is the most soluble gas with mole fraction solubilities of the order of 10⁻². Ethane and methane are one order of magnitude more soluble than the other five gases that have mole fraction solubilities of the order of 10⁻⁴. Hydrogen is the less soluble of the gaseous solutes studied. From the variation of solubility, expressed as Henry’s law constants, with temperature, the partial molar thermodynamic functions of solvation such as the standard Gibbs energy, the enthalpy, and the entropy are calculated. The precision of the experimental data, considered as the average absolute deviation of the Henry’s law constants from appropriate smoothing equations is of 1%.     

Effect of pressure on the solubilities ofo-,m- andp-xylene in water

The solubilities of o-, m- and p-xylene in water were measured at 25.0°C up to 250, 385, and 50 MPa, respectively. The solubility increased with increasing pressure up to 120 MPa (50 MPa for p-xylene) and then decreased. The reaction volumes, V^o accompanying the dissolution at 0.1 MPa were estimated as –3.6±0.5, –3.4±0.5, and –4.1±0.5 cm³-mol^–1 for o-, m-, and p-xylene, respectively, from the pressure dependences of the solubilities. The limiting partial molar volumes, of p- and o-xylene in water under high pressure were estimated from V^o and the molar volume of the xylene. The partial molar volumes decreased with increasing pressure. The reaction volume for the formation of intra-molecular pairwise hydrophobic interaction between the methyl groups, as proposed by Ben-Naim, is discussed for the V^o of p- and o-xylene at 0.1 MPa.     

Heat Capacities and Thermodynamic Properties of Fenpropathrin (C22H23O3N)

The heat capacities of fenpropathrin in the temperature range from 80 to 400 K were measured with a precise automatic adiabatic calorimeter. The fenpropathrin sample was prepared with the purity of 0.9916 mole fraction. A solid—liquid fusion phase transition was observed in the experimental temperature range. The melting point, T_m, enthalpy and entropy of fusion, _fusH_m, _fusS_m, were determined to be 322.48±0.01 K, 18.57±0.29 kJ mol^–1 and 57.59±1.01 J mol^–1 K^–1, respectively. The thermodynamic functions of fenpropathrin, H_(T)—H_(298.15), S_(T)—S_(298.15) and G_(T)—G_(298.15), were reported with a temperature interval of 5 K. The TG analysis under the heating rate of 10 K min^–1 confirmed that the thermal decomposition of the sample starts at ca. 450 K and terminates at ca. 575 K. The maximum decomposition rate was obtained at 558 K. The purity of the sample was determined by a fractional melting method.This revised version was published online in November 2005 with corrections to the Cover Date.     

Solubility of methane in aqueous solutions of triethylenediamine

The solubilities of methane were measured in water and aqueous solutions of triethylenediamine (TED), triethylenediamine hydrochloride (TED·HCl), and HCl at several concentrations up to 1M at 5° intervals from 5 to 25°C. Methane solubilities in solutions of TED·HCl and HCl are lower than those in water and decrease with increasing cosolute concentration. In contrast, the solubilities in TED solutions are greater than those in water and increase with increasing TED concentration. The order of methane solubilities at 25°C in water and in 0.5M aqueous solutions is TED>H₂O>HCl>TED·HCl with Ostwald coefficients of 3.57×10^–2, 3.44×10^–2, 3.26×10^–2, and 3.19×10^–2, respectively, and with an experimental precision of about ±0.2×10^–3. Thermodynamic functions for the transfer of methane from water to 0.25, 0.50, and 0.75M aqueous solutions have been calculated on the molar concentration scale. The free energies of transfer are compared with previous results for methane in aqueous solutions of tetraalkylammonium halides.     

Tensimetric investigation of the CrCl<Subscript>3</Subscript>—Cl<Subscript>2</Subscript> system in the temperature range of 600–1200 K

The sublimation pressure of chromium trichloride was measured by the static method with a quartz membrane-gauge manometer in the temperature range of 875–1230 K. An approximating equation for the sublimation pressure vs. temperature was found. The enthalpy (259.4±4 kJ mol^–1) and the entropy (224.2±3.5 J mol^–1 K^–1) of sublimation at 298 K were calculated. For the process 2 CrCl₃(g) + Cl₂(g) = 2 CrCl₄(g), the following values were obtained: _r H°₂₉₈ = –207.1±11.6 kJ mol^–1 and _r S°₂₉₈ = –173.6±10 5 J mol^–1 K^–1.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1561–1564, August, 2004.     

The MCD spectrum of matrix-isolated osmium tetroxide

The MCD spectrum of OsO₄ in argon and nitrogen matrices at ≈ 20 K has been measured and is remarkably similar to the first band of MnO₄⁻ in KIO₄ at 4.2 K. From this it is concluded that there are two electronic origins in the region 30 000–39 000 cm⁻¹ and the spectrum of OsO₄ is reassigned accordingly.