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61.
From measurement of the heat of hydrolysis, at 25°C , the enthalpy of formation of rubidium tetrafluoroiodate is derived: ΔH°f [RbIF4, cryst.]298= ?191.12±4.43 kJ mol?1. Heat capacity measurements for RbIF4 over the range 273–303 K are also reported. 相似文献
62.
M.M.J. Pieterse M. Sluyters-Rehbach J.H. Sluyters 《Journal of Electroanalytical Chemistry》1980,107(2):247-256
The reduction of oxygen to hydrogen peroxide at a dropping mercury electrode in an aqueous solution of 1 M KNO3+0.04 M KOH (pH=12.35) has been studied by means of impedance measurements as a function of frequency and d.c. potential. The reaction appears to be nearly reversible in the dc sense, but quasi-reversible in the ac sense. The impedance data obey the Randles' equivalent circuit with the following apparent values for the kinetic parameters: standard heterogeneous rate constant ksha=0.035 cm s?1 and cathodic transfer coefficient αac=0.22. The results are interpreted in terms of a two-step charge transfer mechanism with the step O2+eO2? being rate-determining. 相似文献
63.
The behaviour of commercial, membrane-covered dissolved oxygen detectors is considerably more complicated than the orginal model of Mancy et al. would suggest. For example, the steady-state current is dependent both on the thickness and nature of the electrolyte behind the membrane. And transient currents obtained for switch-on of the detector are not completely described by the simple diffusional model. This paper examines these examples of more complicated behaviour. An analysis of the transient current for a step change in dissolved oxygen concentration is also given. 相似文献
64.
The ketol and its acetate when refluxed in methanolic potassium hydroxide (5%) were found to rearrange to 4-methyl-8-acetyl-5,6,7,8-tetrahydro-1-naphthol . The epimeric acetate also behaved likewise. A mechanism is suggested for the rearrangement. 相似文献
65.
Thomas T. Tidwell 《Tetrahedron letters》1979,20(48):4615-4618
Diethylketene and organometallic reagents form enolates capturable by methyl iodide or trimethylsilyl chloride with greater than 95% positional selectivity. 相似文献
66.
D. Bahadur Sheelavathi Kollali C.N.R. Rao M.J. Patni C.M. Srivastava 《Journal of Physics and Chemistry of Solids》1979,40(12):981-985
FMR measurements have been carried out on several members of the Ln1−xSrxCoO3 (Ln = Rare earth) system. The results show that geff in these systems is around 1.25 independent of x as well as the rare earth ion. It is suggested that this unusual value of geff is due to the localized intermediate-spin Co3+ ions (t52g e1g) located at the top of the π* band. 相似文献
67.
The electrochemical one-electron oxidation of 9-hydroxy-ellipticinium cations at a platinum electrode has been examined with particular attention to the thermodynamic redox potential and to the dimerization rate of the radical species produced. Both the reactant and the product of the electrochemical reaction are strongly adsorbed at the solution/electrode interface. The initial step of the anodic process is a reversible electron transfer accompanied by a fast deprotonation; E0′=900?53 pH mV vs. NHE. The resulting neutral radical dimerizes, the rate constant of the surface dimerization being ca. 2.5×109 mol?1 cm2 s?1. 相似文献
68.
Amorphous Fe74Co10B16 (METGLAS 2605CO) has been studied in the temperature range of 77 K – 700 K by Mössbauer spectroscopy. Its crystallization temperature is found to be 665 ± 5 K and Curie temperature is estimated to be 760±10 K. The observed rapid decrease in reduced hyperfine fields can be explained well by Handrich's model for amorphous ferromagnets if one assumes a temperature dependent δ, a measure of fluctuations in the exchange interactions in such solids. 相似文献
69.
While considering the self-diffusion processes in aqueous electrolyte solutions, transport of ions, not only by jumps of single ions, but also by jumps of their solvation shells, are to be taken into account. Samoilov estimated the relative number of the two kinds of ionic jumps from experimental data on diffusion assuming an approximately uniform value for the α factor. In the present paper entirely different theory of the α factor based on the structural hydration model of one of the authors (S.V.T.) for alkali metal ions is given and its ion-wise values are calculated at different temperatures. The theory not only dispenses with the approximate fixation of α but also throws light on the structure of water, formation of clusters and their population variation with temperature. 相似文献
70.