ISSN:0005-9021    

DOI:10.1002/bbpc.19820860202

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

年代:1982

数据来源: WILEY

摘要:

AbstractPVT‐measurements on gaseous H2S up to 760 K and 600 bar were performed. The hot gas was in contact with silica only, so that no corrosion occurred. The results together with literature data were compared with equations of state, the parameters of which had been fitted by least‐squares‐methods. The Redlich‐Kwong‐equation is recommended for calculations, because values computed from this equation do not differ more from the measured values than those computed from equations with more than two p

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860203

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

年代:1982

数据来源: WILEY

摘要:

AbstractWe describe an expansion apparatus for measurements of second virial coefficients of pure gases and mixtures at room temperature. We present experimental data of CO, CO2, Xe, CH4, CF4and of the binary mixtures Ne/Xe, Ar/N2, Ar/CO, Ar/CO2, and CH4/CF4.

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860204

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

年代:1982

数据来源: WILEY

摘要:

AbstractNonstoichiometry and point defect structure of magnetite have been studied experimentally by thermogravimetry covering the stability range of magnetite between 900 and 1400 °C. A cation deficit is observed at high and a cation excess at low oxygen activities corresponding to cation vacancies and iron interstitials as the predominant point defects, respectively. An overexponential temperature dependence occurs for the defect concentrations in stoichiometric magnetite

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860205

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe reaction OH + HO2→ H2O + O2(1) was studied at room temperature in several isothermal discharge‐flow reactors. OH‐ and HO2‐radicals and O‐atoms were monitored with an optically pumped lmr‐spectrometer. The radicals were produced by the reaction F + H2O → OH + HF and OH + HO2H2O, F + H2O2→ HO2+ HF or H + O2+ M → HO2+ M, respectively. The influence of side reactions due to the presence of H2O2or the possible presence of O‐ or H‐atoms with small concentrations was investigated and eliminated or taken into account by using suitable reaction conditions. The rate constant at room temperature was found to bek1(296 K) = (4.0 ± 1.4) · 1013cm3/mol s.In the range 2 mbar ≤p≤ 14 mbark

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860206

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe fluorescence lifetime of trans‐stilbene in solution was measured in the temperature range 300–80 K by three different methods. The decay was found to be mono‐exponential throughout, but prone to falsification by impurities, which may be responsible for the bi‐exponential decays reported by some authors. At room temperature τFis 80–130 ps, increasing to 1200–140

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860207

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics of hydration of 17 different carbonyl compounds have been studied in acidic solution. The reactions have been found to be acid‐catalysed. For the aliphatic aldehydes propanal to hexanal the rate constants arek0= (3.5 ± 1) · 10−3s−1andkH= (450 ± 30) dm3mol−1s−1and for α‐keto acids they are in the rangesk0= (0.13 to 0.40) s−1andkH= (1 to 6) dm3mol−1s−1. For halogenated acetones the rate constants depend strongly on the substituents. The large negative value for the reaction entropy ΔS0= −70 J mol−1K−1indicates that three water molecules are invol

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860208

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe35Cl NQR spectra of 22 hemiacetals of chloral, Cl3CCH(OH)OR, were studied. Most of these hemiacetals with R = unbranched aliphatic group, show a three line35Cl NQR spectrum having a regular splitting pattern; two lines aroundvL= 38.6± 0.1 MHz and the third line atvH= 39.0 ± 0.1 MHz. It is assumed that the difference betweenvLandvHis due to “chemical splitting”. Completely irregular splitting pattern are found for the hemiacetals carrying bulky branched aliphatic groups. Moreover the magnitudes of these splittings are relatively large. A deformation of the molecules due to intramolecular steric hindrance seems to be responsible for this large splitting. The frequency shift in these compounds due to the steric effect is estimated to be 1 MHz or less. A peculiar temperature dependence of the35Cl NQR line intensity was found for chloral n‐butylhemiacetal. An intramolecular bifurcated hydrogen bond between CCl3and OH groups is proposed to be responsible for the phenomenon. For p‐chlorobenzylalcohol at ca. 226 K a phase transition was

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860209

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe theoretical and experimental principles of a novel method for the direct and rapid measurement of single ionic drift velocities in electrolytes are presented. The method is based on an NMR flow measuring technique and the velocity information is obtained through the observation of the spin‐echo amplitude in the presence of a pulsed magnetic field gradient and a pulsed electric field. It allows the determination of ionic mobilities and transference numbers in a more “direct” way than the classical electrochemical methods. First experimental results for (C2H5)4N+‐ions in aqueous solution are shown. Advantages, disadvantages and possible applications of this new NMR method in electrochemistry are discussed. It seems that the method has special advantages for measurements of electrical transport data in solutions of mixed electrolytes. The observation ot solvent motions in conducting electrolyte solutions could also be a possible appl

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860210

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

年代:1982

数据来源: WILEY

摘要:

AbstractLigand exchange on tetrakis(methylmethylphenylphosphinate)beryllium(II), [Be(mmpp)4]2+, and its dimethylmethylphosphonate analogue, [Be(dmmp)4]2+, has been studied in CD3NO2, CD3CN, and CD2Cl2solvents using1H (90 MHz) NMR methods. When the solvent is CD3CN or CD2Cl2ligand exchange on [Be(mmpp)4]2+exhibits a rate independence of [mmpp]freewhereas when the solvent is CD3NO2the ligand exchange rate =k24[Be(mmpp)2+4][mmpp]freewherek2(298.2K) = 0.22 ± 0.01 dm3mol−1s−1, ΔH≠= 68.7 ± 0.9 kJ mol−1, and S≠ = −26.1 ± 2.7 J K−1mol−1. When the solvents is CD2Cl2ligand exchange on [Be(dmmp)4]2+exhibits a rate independence of [dmmp]freewhereas when the solvent is CD3CN the ligand exchange rate = 4(k1+k2[dmmp]free) [Be(dmmp)2+4] wherek1(298.2 K) = 0.93 ± 0.04 s−1, ΔH≠ = 64.3 ± 1.2 kJ mol−1, ΔS*= −29.7 ± 3.7 J K−1mol−1,k2(298.2 K) = 0.33 ± 0.05 dm3mol−1s−1, ΔH≠ = 69.4 ± 4.4 kJ mol−1, and ΔS≠ = ‐ 21.3 ± 13.1 J K−1mol−1. These data are interpreted in terms of dissociative (D) and associative (A) ligand exchange mechanisms and the effect of the solvent on mechanism is discussed. An apparent ΔH≠/ΔS≠isokinetic relationship is used as the basis of a compa

ISSN:0005-9021    

DOI:10.1002/bbpc.19820860211

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

年代:1982

数据来源: WILEY