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91.
S. L. Gupta 《Colloid and polymer science》1958,160(1):30-32
Summary The effect of methylene blue under different conditions of pH, concentration and frequency of the a. c. ripple used has been investigated on the capacity of the dropping mercury electrode.
All the peaks caused by methylene blue at different pH values have been interpreted as due to the reduction of the methylene blue, as indicated by the comprehensive study of the
peaks. The halt at about 0.58 Volt at pH 5.8 is due to desorption which develops into a satellite peak if potassium nitrate is used as indifferent electrolyte. It
is found that the peak at 1.35 Volt at pH 12.3, first increases with increase in concentration and then diminishes at still higher concentrations. The causes of this
have been discussed. The effect of frequency reveals that the reduction reactions involved are rather slow.
Zusammenfassung Der Effekt von Methylenblau unter verschiedenen Verh?ltnissen von Wasserstoff-Ionen-Konzentration, Konzentration und Frequenz des überlagerten Wechselstroms auf die Kapazit?t der Quecksilbertropfelektrode war Gegenstand der Untersuchung. Alle dem Methylenblau zuzuschreibenden Maxima bei verschiedenen pH- Werten lassen sich interpretieren durch eine Reduktion des Methylenblau, wie die eingehende Untersuchung der Maxima zeigt. Der Konstanzbereich bei etwa 0,58 Volt und pH 5,8 ist einer Desorption zuzuschreiben, die ein Begleitmaximum entwickelt, wenn Kaliumnitrat als indifferenter Elektrolyt verwendet wird. Das Maximum bei 1,35 Volt und pH 12,3 w?chst zun?chst bei Steigerung der Konzentration und nimmt dann bei noch h?heren Konzentrationen wieder ab. Die Gründe hierfür werden diskutiert. Der Frequenzeffekt zeigt an, da? die Reduktionsreaktionen ziemlich niedrig sind.相似文献
92.
Thorwirth S McCarthy MC Gottlieb CA Thaddeus P Gupta H Stanton JF 《The Journal of chemical physics》2005,123(5):054326
The sulfur molecules thiozone S3 and tetrasulfur S4 have been observed in a supersonic molecular beam in the centimeter-wave band by Fourier transform microwave spectroscopy, and in the millimeter- and submillimeter-wave bands in a low-pressure glow discharge. For S3 over 150 rotational transitions between 10 and 458 GHz were measured, and for S4 a comparable number between 6 and 271 GHz. The spectrum of S3 is reproduced to within the measurement uncertainties by an asymmetric top Hamiltonian with three rotational and 12 centrifugal distortion constants; ten distortion constants, but an additional term to account for very small level shifts caused by interchange tunneling, are required to reproduce to comparable accuracy the spectrum of S4. Empirical equilibrium (r(e)(emp)) structures of S3 and S4 were derived from experimental rotational constants of the normal and sulfur-34 species and vibrational corrections from coupled-cluster theory calculations. Quantum chemical calculations show that interchange tunneling occurs because S4 automerizes through a transition state with D2h symmetry which lies about 500 cm(-1) above the two equivalent C2upsilon minima on the potential energy surface. 相似文献
93.
Indoles undergo smooth coupling with phenylacetylene in the presence of 10 mol % of gallium(III) chloride or gallium(III) bromide under mild conditions to afford the corresponding 1,1-bis(1H-3-indolyl)-1-phenylethanes in high yields and with high selectivity. 相似文献
94.
95.
Summary Rate constants for the oxidation of thiosulphate by hexachloroplatinate(IV) have been measured. The kinetics of the oxidation of thiosulphate follow a second-order rate law, first order with respect to thiosulphate and first order with respect to platinum(IV). The influence of pH is small. The rates are found to depend on the nature and concentration of the cations and follow the order: Cs+>Rb+>K+>Na+>Li+. The activation parameters calculated from the temperature studies are: H=42.9 k J mol–1 and S=–102 JK–1 mol–1. A mechanism of the reaction in terms of intermediate formation of free radicals followed by the formation of tetrathionate is postulated to explain the kinetic behaviour. 相似文献
96.
Dinesh Kumar Ashu Rani D. S. N. Prasad K. S. Gupta 《Reaction Kinetics and Catalysis Letters》1991,43(1):133-141
The kinetics of the oxidation of 2-furancarboxaldehyde by thallic perchlorate at 50°C obeys the rate law
相似文献
97.
Kalyan Kali Sen Gupta Ambikesh Mahapatra Balaram Ghosh 《Transition Metal Chemistry》1991,16(5):500-502
Summary The reactivities of - and -glycerophosphates towards MnO
4
–
in HClO4 medium have been examined. The reactions between glycerophosphates and MnO
4
–
are first order with respect to [glycerophosphate], [MnO
4
–
] and [H+]. There is no evidence for cleavage of the C–O–P bond rather than the terminal –CH2OH group being oxidized to the respective phosphoglyceraldehyde. 相似文献
98.
99.
100.
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