Electrical Conductance and Density in Molten Tungsten(VI)-oxide-Alkali (Li, Na, K) Tungstate Systems.

Morris, Kelso B.; Robinson, Percy Lucock

doi:10.1021/je60022a048

Cited by 11 publications

(6 citation statements)

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“…All data are normalized for the catalase-like activity of ComHP at pH 8: »o = 5.6 X 10-6 mol l.-1 sec-1. 6 This work. " These complexes tend to dimerize or polymerize in aqueous solution;23,25 however, the most active catalyst is probably the monomer species.…”

Section: Discussionmentioning

confidence: 95%

“…These complexes tend to dimerize or polymerize in aqueous solution;23,25 however, the most active catalyst is probably the monomer species. 1,5,6 The data given correspond, for example, to [FemPTS]tot = 10-4 M. 'In a 10-4 M solution only about 1% is present as FemPTSmonomer•6,23 « H. Sigel and K. Wyss, to be submitted for publication.…”

Section: Discussionmentioning

confidence: 98%

“…All the other reagents and the apparatus were the same as used earlier. 6 Measurements of Catalysis and Evaluation of the Data.-These were done exactly as described recently. 6 The logarithms of the initial rates, v0, of the O2 formation according to reaction 1 were plotted vs. the varied concentrations of the reagent, A.…”

Section: Methodsmentioning

confidence: 99%

“…6 Measurements of Catalysis and Evaluation of the Data.-These were done exactly as described recently. 6 The logarithms of the initial rates, v0, of the O2 formation according to reaction 1 were plotted vs. the varied concentrations of the reagent, A. From the slope of the straight-line portion of the plots the relation between the reaction rate and the concentration of the reagent, A, was taken.…”

Section: Methodsmentioning

confidence: 99%

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Metal ions and hydrogen peroxide. XXVI. Kinetics and mechanism of the catalase-like activity of cobalt(III) hematoporphyrin

Waldmeier¹,

Sigel²

1972

Inorg. Chem.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Metal ions and hydrogen peroxide. XXVI. Kinetics and mechanism of the catalase-like activity of cobalt(III) hematoporphyrin

Waldmeier¹,

Sigel²

1972

Inorg. Chem.

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“…The molarities of the melts were calculated using density data reported by Morris and Robinson (19).…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Deposition of Sodium Tungsten Bronzes

Randin

1973

J. Electrochem. Soc.

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The electrochemical deposition of sodium tungsten bronzes (NaxWO3) from Na2V~O4/V~rO3 melts has been studied between 700 ~ and 900~The relation between the x-value in NaxWO3 and the concentration of WO~ in the melt is linear between 2 and 10 mole/liter WO~. Extrapolation of the linear section gives x = 1.0 at zero concentration of WO~. The current efficiency of the bronze deposition depends on both the applied current and the melt temperature. This dependence is attributed to the occurrence of simultaneous chemical dissolution of the bronze. A transition temperature has been found below which NaxWO3 is deposited, and above which W (or W + NaxWO3) is obtained. The nature of the deposit is a function of the melt composition and temperature. The slope of the (i),=const. vs. T -1 plot shows no break at, or near, the transition temperature, indicating that the rate-determining step for the deposition of NaxWO3 is the same as that for the deposition of W. The tungsten formation occurs most likely by decomposition of the previously deposited bronze. The content of platinum in a platinum-containing bronze is favored by a high temperature. The amount of platinum codeposited in the bronze is small compared to the amount of platinum dissolved from the anode. A relatively high concentration of platinum in the melt inhibits the bronze deposition. A nonelectrochemical reaction is believed to be responsible for the codeposition of platinum.The sodium tungsten bronzes are nonstoichiometric compounds of the general formula NaxWO3, where 0 < x --~ 1. They are chemically inert and have semimetallic properties, in particular, metallic luster and good electrical conductivity. Their properties have been reviewed recently (1-3).Two methods have been extensively used for the preparation of these bronzes. The first method involves a solid-state reaction between a mixture of fine powders of sodium tungstate, tungsten trioxide, and metallic tungsten, the latter acting as a reducing agent, at a temperature between 500 ~ and 1000~ in a nonoxidizing atmosphere. This reaction may be written asThe bronzes produced by this technique are in the form of fine powders (4, 5).The second method involves the electrolysis of a molten mixture of sodium tungstate and tungsten trioxide; it is essential when large single crystals are required. Crystal growth occurs at the cathode and oxygen evolution takes place at the anode, according to the over-all reactionThe growth of tungsten bronzes by fused salt electrolysis has been used by a number of investigators [see, for example (6-11)], but virtually no details about the actual growth method were reported until very recently. Banks, Fleischmann, and MeRes (12) performed polarographic experiments which revealed a polymeric character of the WO8 species reduced at the cathode for a melt concentration between 10 and 60 m/o (mole per cent) WO3 and a temperature of 750~ This work confirmed an earlier Raman spectroscopic investigation in which the formation of polyions in a Na~WO4/WO3 melt at 710~ was suggested (13)...

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