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1.
S. B. Zhilova Z. G. Karov R. M. El’mesova 《Russian Journal of Inorganic Chemistry》2008,53(4):628-635
Solubility in the Na2MoO4-Na2SO4-H2O system was studied using isothermal saturation at 5–100°C. The boundaries of crystallization fields were determined for sodium sulfate and sodium molybdate. Solid solutions were not observed within the range of the temperatures studied. The density, refractive index, and dynamic viscosity of the saturated solutions of the system were determined, and these data were used to calculate the molar volume, kinematic viscosity, and apparent molar volume of the sum of salts in these solutions. All property isotherms of solutions are in a strict correlation with the solubility in the system; this correlation is represented as an isobaric-isothermal diagram. 相似文献
2.
Velocity cross-correlation coefficients have been calculated for aqueous solutions of NiCl
2
and MgCl
2
up to concentrations of 4M. Examination of the concentration-dependence of these coefficients show that it is very similar for the two salts. There is no evidence for any special structural characteristics in NiCl
2
solutions. The velocity correlation technique is apparently not sensitive enough to detect the small amount of complexation that is thought to be present in NiCl
2
solutions. 相似文献
3.
M. N. Nikolaeva G. P. Aleksandrova A. A. Martynenkov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(5):812-815
A correlation is found between the proton spin-spin relaxation times in gold nanocomposites based on arabinogalactan in aqueous
solutions and the maximum conducting layer thicknesses of films cast from solutions of composites. The obtained correlation
is considered from the viewpoint of electrization’s effect on the mobility of macromolecules of the investigated polymer nanocomposites.
The dependence of arabinogalactan mobility on the type of solvent (H2O or D2O) is established, and a conclusion is drawn as to the effect of the hydrogen bonds of arabinogalactan with solvent on polymer
mobility in solutions. 相似文献
4.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(10):1527-1535
The Raman spectra of the totally symmetric ν1(Σg+) mode of XeF2 molecules have been measured in CH3CN solutions at various temperatures and concentrations. The vibrational and rotational correlation functions as well as the characteristics times have been calculated. It was concluded that the vibrational band width in these solutions is to be attributed to the vibrational dephasing, whereas the contribution from the rotational relaxation has been found to be of less importance. 相似文献
5.
The EPR spectrum of 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO) has been systematically investigated in several solvents and in aqueous solutions of glycerol,t-BuOH, Bu4NBr,n-HexNH3Br,n-OctNH3Br, NaBPh4, and Ph4AsCl. Most of the results have been obtained at 25°C, though the temperature dependence of the linewidths has been examined in water and several organic solvents. Data on the spectrum of ditertiarybutylnitroxide in aqueous solutions of glycerol and Bu4NBr are also presented. The spectrum was simulated to determine WH, the linewidth after allowance for the unresolved proton hyperfine interaction, in each manifold of the triplet due to the nitrogen hyperfine interaction. The linewidth WH is analyzed in terms of the reorientational correlation time Äθ and the angular velocity correlation time ÄJ. In most solutions Äθ is determined only by the bulk solution viscosity, except in situations where significant clustering of hydrophobic solute molecules occurs. In pure nonaqueous solvents the temperature dependence results are consistent with ÄJ being determined by the bulk viscosity, while in water or aqueous solutions, a very different behavior is found which is interpreted as a manifestation of clathrate-like hydration of the hydrophobic radical. This interpretation is incorporated in a two-state model developed to account for the WH data of TEMPO in aqueous solutions of various hydrophobic solutes. The equilibrium parameters derived from the model, for the association of TEMPO with several hydrophobic solutes, support the concept of hydrophobic interactions as pictured from thermodynamic excess functions. 相似文献
6.
Vapor pressure data for solutions of various alkali metal and tetraalkylammonium salts in methanol at 25° and NaI solutions in ethanol, 2-propanol, and acetonitrile at 25° in the concentration range 0.04–1]<0.75 are used to show the applicability of the HNC integral equation method to nonaqueous electrolyte solutions. Friedman's model of overlapping cospheres is used to express the non-electrostatic part of the ion-interaction potential. Data analysis is based on the Rasaiah-Friedman algorithm for the calculation of g++ and g+– functions. After conversion from Lewis-Randall to the McMillan-Mayer system the measured osmotic coefficients of all electrolyte solutions can be reproduced with the help of the calculated correlation functions. 相似文献
7.
The isotropic lineshape of the v1 (A1) stretching mode of the nitrate ion in solutions of sodium nitrate has been studied at 25°C as a function of NaNO3 concentration ranging from 0.1 to 6M. The pressure dependence has been determined for 1 and 6M solutions at pressures ranging from 1 bar to 3 kbar. The isotropic band becomes more asymmetric with increasing concentration, and its v1 peak frequency undergoes a blue shift both with increased concentration and increased pressure. At low concentration the vibrational correlation function is well described by the Kubo formula, whereas at higher concentration it becomes more Gaussian. The experimental data indicate that the v1 vibrational lineshape in aqueous solutions of NaNO3 is dominated by strong intermolecular interactions which produce inhomogeneous broadening at higher concentration. 相似文献
8.
M. M. Gafurov K. Sh. Rabadanov V. D. Prisyazhnyi D. O. Tret’yakov M. I. Gorobets S. A. Kirillov M. B. Ataev M. M. Kakagasanov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(9):1499-1504
The phase diagrams, isotherms of the electrical conductivity, Raman spectra, and time correlation functions of vibrational
dephasing are studied for the LiN(CF3SO2)2-(CH3)2SO2 system, which is promising for use as an electrolyte in medium-temperature lithium-ion batteries. The phase diagram of this
system contains a broad supercooled region. It is shown that the concentration dependences of the electrical conductivity
are typical for solutions of strong electrolytes. The Raman spectra and the time correlation functions of vibrational dephasing
for the anion and the solvent indicate that in the supercooling range, cations are weakly solvated by solvent molecules and
form ion pairs. 相似文献
9.
《Chemical physics》1987,116(1):101-111
The 2D and 19F spin-lattice relaxation times of 1,3,5-trifluorobenzene-d3 in 0.15 mol fraction solutions in various solvents have been measured over the temperature range 270–400 K. The relationship between the reorientational correlation times, τθ, and the angular momentum correlation times, τJ, obtained from the nuclear relaxation data has been compared with the theoretical relationships predicted by the J-diffusion limit of the extended diffusion (EDJ) model and the Fokker-Planck-Langevin (FPL) model for symmetric top molecules. It was found that the rotational motion of 1,3,5-trifluorobenzene-d3 in most solutions was better described by the FPL model with frictional anisotropy τ6/τ· in the range 1–2. (τ6 and τ· are the correlation times for the angular velocity components along the axes parallel and perpendicular to the molecular symmetry axis.) The viscosity and temperature dependence of τθ has been analyzed in terms of a modified Debye equation and values for the anisotropic interaction parameter, κ, in each solvent are reported. The variation in κ with solvent is attributed mainly to the variation in the dipole moment of the solvent molecules. The frictional anisotropy (τ6/τ·) is found to decrease as κ increases. This is interpreted in terms of the effects of molecular shape and electrostatic interactions between CF bond dipole moment and solvent dipole moments. 相似文献
10.
The osmotic coefficients for CoSO4, NiSO4, CuSO4, MnSO4, and ZnSO4 have been found to be approximately the same up to very highest concentrations, while they are significantly higher for MgSO4. Negligible changes in the visible spectra of CoSO4 and NiSO4 induced by increasing concentration indicate little, if any, coordination of the sulfate anion, while the UV spectral effects indicate outer-sphere association. More distinct spectral effects are observed for CuSO4. However, the free sulfate anion concentration is found to be the same in equimolal solutions of CoSO4, NiSO4, and ZnSO4, and probably also in CuSO4, while it is higher in the solutions of MgSO4. The conclusion is drawn that the four isopiestic transition metal sulfates at any given molality are in corresponding coordination states. The general problem of correlation between thermodynamic properties of solutions and the coordination states of the dissolved salts is discussed. 相似文献
11.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1993,49(10):1537-1546
The Raman spectra of the totally symmetric ν1(Σ+g) mode of xenon dilluoride molecules have been measured in HF and BrF5 solutions at various concentrations. It is shown that the XeF2 spectrum in HF has a complicated structure with three visible peaks. The complicated contour was resolved on elementary components which were identified. The vibrational and rotational correlation functions as well as the characteristics times have been calculated. It was concluded that the ν1 vibrational band width of XeF2 molecules in HF and BrF5 solutions is to be attributed to the vibrational dephasing, whereas the contribution from the rotational relaxation has been found to be of less importance. 相似文献
12.
The optical absorption spectra observed by pulse radiolysis of alkaline (NaOH, KOH, RbOH), chloride (LiCl, MgCl2, CaCl2, NaCl, KCl) and perchloride (NaClO4) solutions at temperature 298 K are reported. Some measurements were performed at low temperature with aqueous ionic glasses. With increasing concentration of the above solutes a uniform blue-shift of the maximum of the solvated electron (e¯sol) absorption band is observed. Near infrared (NIR) spectroscopy was so used to examine the properties of water in several concentrated electrolyte solutions. It is shown that some inorganic electrolytes (e.g. NaOH, NaClO4) substantially change the water structure whereas some others (e.g. LiCl, CaCl2) influence water structure insignificantly. The correlation between the ability of excess electron trapping in electrolyte solutions and water structure deduced from NIR spectroscopy is discussed. 相似文献
13.
The 13C NMR spectra of uridine and cytidine in d6-DMSO, d7-DMF, d9-trimethyl phosphate, d4-methanol, d5-pyridine, and D2O were investigated. A linear correlation between the C1' chemical shifts and the J1' vicinal spin-spin coupling constants of the protons was established. From the experimental data it may be assumed that the chief reason for the effect of the solvent on the C1'2' chemical shift is the different contribution of the effect of the base as a consequence of a change in the conformational equilibrium of the ribose ring. Deviations from the correlation in aqueous solutions and solutions of cytidine in pyridine are observed as a result of a change in the electron density in the base. The effect of the nature of the solvent on the position of the conformational equilibrium of the base relative to the glycoside bond was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1550–1552, November, 1980. 相似文献
14.
Summary The solution of both Hartree-Fock (HF) and Kohn-Sham (KS) equations is based on the variational principle. Exact wavefunctions would obey the same symmetry restrictions contained in the total hamiltonian. However, the variational principle does not guarantee these symmetry restrictions and the HF and KS solutions are not necessarily symmetric in spin and space. Spatial and spin symmetry broken solutions with lower energies than their restricted analogues are examined for C2 and Be2, in the context of the KS formalism. Comparison with UHF solutions shows that KS instabilities are far less pronounced. The main differences between HF and KS solutions are related to effects of electron correlation. 相似文献
15.
In this study, the relative pKa values of nine anilinium derivatives in methanol (MeOH), acetonitrile (AN), and tetrahydrofurane (THF) solutions were successfully calculated with mean absolute deviations of 0.63, 0.68, and 0.75 pKa units, respectively. To this aim, their gas‐phase basicities were computed using the CBS‐QB3 composite method. Also, conductor‐like polarizable continuum model (CPCM) with UAHF, UAKS and UA0 cavities and SM8 solvation models at HF/6‐31+G(d) level of theory were applied for the calculation of the solvation Gibbs free energies. The obtained results indicate that there is reliable correlation between the experimental and computed pKa values in the studied solutions. Therefore, to extend the pKa database for anilines, correlation equations were used to predict the pKa values in the investigated solvents. 相似文献
16.
Athinodoros Bandis Paul T. Inglefield Alan A. Jones Wen-Yang Wen 《Journal of Polymer Science.Polymer Physics》1995,33(10):1515-1522
The spin-lattice relaxation times are determined for the methylene carbon of polyisobutylene (PIB), as well as for the ortho carbon of toluene in toluene-polyisobutylene solutions. The Hall-Helfand correlation function combined with restricted anisotropic rotational diffusion was used to treat the T1 data of the methylene carbon of PIB. A simple exponential correlation function was used to describe the local motion of toluene in the solutions which falls in the extreme narrowing limit for the solutions studied. Both models described satisfactorily the temperature and field dependence of the spin-lattice relation times. From the temperature dependence of the correlation times for the polymer segmental motion, the free volume of the solution at each concentration is extracted and compared with the values obtained from previous studies of the translational motion of the toluene penetrant. The free volume values extracted from the T1 data for the methylene carbon of PIB and the self-diffusion data for the toluene were found to be in substantial agreement. The interrelationship of the timescale of segmental motion of the polymer and the translational diffusion of the toluene was also examined and it was found that the two types of motion seem to be correlated in high polymer concentrated solutions. The toluene reorientational motion was found to be much faster than both the polymer segmental motion and the toluene translational diffusion leading to the conclusion that the toluene reorientational motion is uncoupled from these two motions. ©1995 John Wiley & Sons, Inc. 相似文献
17.
The minimal energy conformations of o-benzosemiquinone anion radicals in the solvents containing the alkali metals and the alkali earth metals were calculated by using the INDO method and the molecular geometry adjusting method. Our previous calculations of o-benzosemiquinone anion radical in the lithium ion solution showed that the total energy of the minimal energy conformation in the case of the assignment |A3| > |A4| were lower by approximately 320 kcal/mol than that in the case of the assignment |A3| > |A4|. Therefore, the calculations of the minimal energy conformations of o-benzosemiquinone anion radicals in the metal ion solutions were carried out in the cases of the assignment |A3| > |A4|. The conformations in both assignments A3 < A4 < 0 and (A3 < 0 < A4 and |A3| > |A4|) were calculated. Although the metal ions were not explicitly contained in the molecular geometries, the minimal energy conformations are considered to be close to the real minimal energy conformations of o-benzosemiquinone anion radicals in the metal ion solutions. The C? O bond lengths has a good positive rank correlation with the stabilities of o-benzosemiquinone radicals in the divalent metal ion solutions and the bond angles ∠C3C4H4 had a good negative rank correlation with those stabilities. 相似文献
18.
The Raman profiles of the ν5 mode (802 cm?1) of cyclohexane, ν5 (723 cm?1) of cyclohexane-d12 and ν2 (992 cm?1) of benzene and its deuterated analogs have been measured as a function of concentration in the benzene—cyclohexane liquid system. The vibrational time correlation functions of cyclohexane in benzene solutions have been calculated by Fourier inversion of isotropic band contours. The concentration dependence of the experimental vibrational correlation times computed from the correlation functions and from the half width at half height have been compared with that predicted theoretically for various mechanisms of band broadening. We have tested the Fischer—Laubereau dephasing model and the Knapp—Fischer concentration-fluctuation model. We have found that the latter model reproduces well experimental data only for the ν2 mode of benzene in solution. 相似文献
19.
N. I. Tkhashokov R. S. Mirzoev S. B. Zhilova 《Russian Journal of Inorganic Chemistry》2009,54(10):1655-1661
Solubility in the Li2MoO4-(NH4)2MoO4-H2O system at 25°C was studied. A congruently saturating double molybdate crystal hydrate LiNH4MoO4 · H2O was found to form in the system. The density, refractive index, viscosity, surface tension, and specific electrical conductivity
were measured for saturated aqueous solutions of the system. Molar volume, ionic strength, and equivalent conductivity isotherms
were calculated. A correlation is observed between the variations of these properties of solutions and solubility in the system.
The double salt was recovered and characterized by chemical analysis, IR spectroscopy, and dynamic and quasi-equilibrium thermogravimetry.
A thermolysis scheme is suggested proceeding from the thermal curves and chemical analysis of intermediate phases. 相似文献
20.
The influence of impregnation of aluminum oxide desiccants prepared by centrifugal thermal activation of hydrargillite with alkali (KОН and NaOH) and carbonate (Na2CO3 and K2СО3) solutions on the physicochemical properties of the products was studied. Impregnation with alkali solutions increases the dynamic capacity of the desiccants by a factor of 2 and more, whereas impregnation with carbonate solutions decreases the sorption characteristics of the desiccants at similar texture characteristics. Introduction of alkaline modifiers leads to a considerable decrease in the concentration of Lewis acid sites on the surface and to an increase in the concentration of strong base sites. Linear correlation was revealed between the concentration of strong base sites on the surface of the desiccants and their dynamic capacity in drying of humid air. The desiccants modified by impregnation exhibit not only high static and dynamic capacity, allowing improvement of the drying efficiency, but also considerably enhanced mechanical strength. 相似文献