ISSN:0005-9021    

DOI:10.1002/bbpc.198800030

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe optical absorption spectra of the sulfur homocycles Sn(n= 6–10,12, 15, 20) in methanol or methylcyclohexane solution have been recorded in the region 200–360 nm using a conventional spectrophotometer as well as a diode‐array spectrophotometer. Each compound shows a characteristic absorption curve. The extinction coefficients at 254 nm increase with increasing ring size, and the lowest‐energy absorption maximum shifts to the red with increasing number of atoms in the molecule. The data are used to re‐interprete the published absorption spectra of liquid and irradiat

ISSN:0005-9021    

DOI:10.1002/bbpc.198800031

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractAt very low concentrations tetra‐n‐butylammonium pertechnetate and tetra‐n‐butylammonium perchlorate form ion pairs in benzene Solutions. At room temperature, formation of dimers and larger aggregates begins to occur at concentrations of 10−5mol/1. This behaviour has been investigated quantitatively by the determination of the molecular weight in the case of the perchlorate salt, and by the concentration‐dependence of the pertechnetate phase equilibrium between water and benzene. It could be demonstrated that Bu4NClO4‐dimers and larger aggregates have no apparent dipole moment. Knowing the relative concentration of the monomers from the extraction experiments, the dipole moment of 16.6 Debye has been calculated for the ion pair. Applying an extrapolation method, the dipole moment of Bu4NCIO4was found to be 16.2 Debye. The similarity of the dipole moments is in good agreement with the similar ionic radii of the TcO4−and the ClO4−ions. The charge separation in the ion pairs however, calculated from the dipole moments, is smaller than the sum of cationic

ISSN:0005-9021    

DOI:10.1002/bbpc.198800032

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe shear viscosity η was measured as a detailed function of composition for liquid Hg based alloys containing 0–16 at% In in the temperature range from 320 K. to 520 K. A capillary viscometer of the Ostwald type was used for measurements. — The η increases linearly with the addition of In. This concentration dependence could be well explained by a simple hard sphere theory for η of liquid mixtures, in which the correction of back scattering took an important role. — The isothermal curves of ∂η/∂Tshow a slight depression at a few at% In, particularly at lower temperatures. This phenomenon appears to be related to higher order correlation (HOC) effects, which have been proposed recently for some liquid Hg based alloys by the pr

ISSN:0005-9021    

DOI:10.1002/bbpc.198800033

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractTwenty three alloys Al + Ga + Sb have been studied by the Emf method between 623 and 1300 K using concentration cells of the type:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm FO} + {\rm NO}_3 \to {\rm FO}_{\rm 2} + {\rm NO}_2 } & {k\left(3 \right) = 1 \cdot 10\,\,^{ - 12} {\rm cm s}^{ - - 1} .} & {\left(3 \right)} \\\end{array} $$\end{document}Partial molar functions of aluminium and some equilibrium temperatures were determined; they are in satisfactory agreement with the calculation of Kaufman et al. — The comparison of the experimental ternary ΔmixGAlvalues and the corresponding ones calculated using several empirical equations shows that the best agreement is obtained by Colinet's equati

ISSN:0005-9021    

DOI:10.1002/bbpc.198800034

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe electronic conductivity of liquid Na—Nal and Na—NaBr has been measured over a wide concentration range from dilute to concentrated nonmetallic solutions at different temperatures between 700 and 900°C. Two methods have been applied, the Wagner polarization technique at low metal activities and an ac‐technique at high activities where the concentration has been varied by coulometric titration. A thermodynamic defect model previously used for solids is developed and extended to liquid solutions. It quantitatively describes the concentration and temperature dependence of the thermodynamic properties as well as the charge carrier concentration in these nonmetallic systems. The electronic mobility has been determined and the transport mechanism approaching the nonmetal‐metal transition is d

ISSN:0005-9021    

DOI:10.1002/bbpc.198800035

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractExperimental results for the vapor‐liquid equilibrium in the ternary system ammonia‐carbon dioxide‐water are reported for six temperatures between 373 and 473 Kelvin at total liquid concentrations from 4 to 30 mole percent of ammonia and up to 14 mole percent of carbon dioxide as well as for the binary gaseous electrolyte‐water mixtures at the same temperatures and liquid phase concentrations of up to one mole percent (CO2) and 30 mole percent (NH3) respectively. The newly measured data agree well with the very limited literature data for the binary as well as for the ternary systems. Caused by the low solubility of carbon dioxide in water, the experimental results for that binary are described applying Henry's law. For correlating the results for the ammonia‐water system. Henry's law has to be corrected by introducing activity coefficients. The model of Edwards et al. with recently published new parameters is used to compare the experimental results for the ternary with existing correlations. Deviations between predicted and measured total and partial pressures amount up to 60 percent, thus indicating that the model needs further im

ISSN:0005-9021    

DOI:10.1002/bbpc.198800036

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe nuclear magnetic relaxation rates of some ions are studied in aqueous PEO solutions. The relative molal increase of the ion relaxation is obtained for a number of ions. In a limited range the DP‐dependence, salt concentration dependence and temperature dependence are investigated. The quadrupolar relaxation mechanism of ions provides a means to investigate the ion hydration complex. The enhancement of the ion relaxation rate by the presence of PEO is interpreted by an ion hydrationcomplex‐PEO interaction. Two dynamical models are evaluated. One of the models is able to explain the NMR results and does not contradict the results obtained from neutron diffraction experime

ISSN:0005-9021    

DOI:10.1002/bbpc.198800037

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe heat capacities of four di‐n‐alkylammonium chlorides (di‐n‐pentylammonium chloride, di‐n‐hexylammonium chloride, di‐n‐octylammonium chloride, and di‐n‐decylammonium chloride) were measured fromT= 25 K to 350 K using adiabatic calorimetry. All of the compounds investigated were observed to undergo solid‐solid phase transitions in the temperature region examined. The thermodynamic properties obtained for these compounds were compared with those of the layered perovskites (alkylammonium metal halides) and the mono‐n‐alkylammonium chlorides. The high entropies of the solid‐solid phase transitions suggest that there is a significant amount of conformational disorder in the high‐temperature phase, most likely due to solid‐state alkyl‐chain melting, analogous to the layered perovskites and the monoalkylammonium chlorides. The contribution of a CH2unit to the heat capacity of these complexes was calculated and compared to the n‐

ISSN:0005-9021    

DOI:10.1002/bbpc.198800038

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe basic (x= 2,n= 4), (x= 2,n= 0) and the non‐basic (x= 0,n= 8), (x= 0,n= 0) species of the hydrosodalite system Na6+x[AlSiO4]6(OH)x·nH2O have been studied by23Na MAS‐NMR and1H MAS‐NMR techniques at 297 K. The spectra are discussed in terms of structural data, which are provided by X‐ray and neutron diffraction experiments on hydro‐sodalite phases of identical compositions. The1H MAS‐NMR spectrum of the non‐basic phase Na6[AlSiO4]6· 8H2O confirms the recent neutron diffraction data. The chemical shift of 4.2 ppm correlates to regular water molecules in the sodalite cage, which show hydrogen bonding to the framework oxygens. The1H MAS‐NMR double peak spectrum of the basic hydro‐sodalite species Na8[AlSiO4]6(OH)2· 4H2O correlates with the structural OH groupings (3.4 ppm) and with one proton per ß‐cage (—1.0 ppm) showing a significant magnetic shielding effect. The large diamagnetic shift (—6.5 ppm) of the resonance signal in the1H MAS‐NMR spectrum of the hydroxy‐sodalite Na8[AlSiO4]6(OH)2indicates substantial change in the chemical bond of the hydrogen atom upon dehydration of the tetrahydrate Na8[AlSiO4]6(OH)2· 4H2O at 775 K. — The phases of the non‐basic hydro‐sodalites show23Na chemical shifts of approximately —8 and —9 ppm for the octahedrally coordinated sodium atoms in the octahydrate (n= 8) and in the anhydrous (n= 0) sodalite, respectively. — The23Na chemical shifts of the basic sodalites range from —0.6 to —5.6 ppm, and the species reveal considerable quadrupolar interactions. At least two types of sodium ions are registered in basic hydro‐sod

ISSN:0005-9021    

DOI:10.1002/bbpc.198800039

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY