14 Faraday Manganese

Eventually, much to the consternation of Davy, the name magnesium was adopted for the metal in magnesia alba and manganese for the metal in pyrolusite. Michael Faraday produced magnesium metal in 1833 by the electrolysis of fused anhydrous magnesium chloride. 

An interesting theory of promoter action is based on the belief that interfaces are the seat of catalytic activity—the active centers.1,2 It is apparent that new boundaries will be provided and existing ones altered when one solid is incorporated with another, and the enhanced activity may reside in specific configurations produced at boundaries of the two solids. That boundaries between surfaces can be the seat of activity is supported by the fact that a decomposition or combination may be difficult to start on a solid surface consisting entirely of a single component. Overburnt lime does not hydrate readily because water does not combine except where hydration has already begun.22 Faraday found that hydrated salts do not commence to effloresce unless the surface is scratched. The action of manganese dioxide on the decomposition of potassium... 

A. Harriman, P.A. Christensen, G. Porter, K. Morehouse, P. Neta, and M.-C. Richoux, Decay of High-Valent Manganese Porphyrins in Aqueous Solution and Catalyzed Formation of Oxygen, J. Chem. Soc., Faraday Trans. 1, 82 (1986) 3215. 

After 2 hours or less, solid potassium permanganate should start to crystallize out. This effect will be manifest by an apparent sharp drop in the current efficiency as found by titration, After 2 hours, shut off the current temporarily, remove the anode and clean it (it will be found to be coated with manganese dioxide), and restore the alkalinity of the solution by adding 1 mole of solid potassium hydroxide for each faraday of electricity passed. If this is not done, potassium bicarbonate will crystallize along with the permanganate. 

The catalytic activity of co-ordination compounds in oxidations continues to be examined and, together with the Faraday Society Discussion, other aspects of this area of investigation have been the subject of recent reviews. Redox reactions involving bipyridyl and u-phenanthroline complexes of transition metals have been discussed and catalytic oxidations of complexes of manganese, cobalt, copper, and palladium have also been surveyed. Reviews are also available of ruthenium ammine chemistry, and redox reactions involving molybdenum complexes, together with an account of catalase and peroxidase reactivity of copper(ii) complexes. ... 

In (I) (1833) he says he had confirmed Pfaff s experiments with the condenser plates in a vacuum and various gases, and withdrew his own results. He thought the results were due to traces of oxygen in the vacuum and in the inert gases. He also admitted that it was difficult to explain Volta s experiments on the production of charges by the contact of manganese dioxide and platinum, which BecquereP later decided was due to contact action. P. S. Munck af Rosenschold, assistant in physics in Lund, showed that lead dioxide acted like manganese dioxide in cells, and De la Rive and Faraday (XVII, 2043) showed that it is probably reduced. 

EXERCISE 5.1.- Using Faraday s law (see section 2.3.2.2), calculate the theoretical mass capacity of the manganese oxide electrode. 

Grzybek T, Klinik J, Rogoz M, Papp H (1998) Manganese supported catalysts for selective catalytic reduction of nitrogen oxides with ammonia - Part 1 - Characterization. J Chem Soc-Faraday Trans 94 (18) 2843-2850... 

Jaeger FM, Van Klooster HS (1916) Investigations in the field of silicate chemistry. IV. Some data on the meta- and orthosilieales of the bivalent metals beryllium, magnesium, calcium, strontium, barium, zinc, cadmium and manganese. Proc Kon Ned Akad Wet 18 896-913 Bockris JO M, TomUnson JW, While JL (1956) Stmeture of the liquid silicates partial molar volumes and expansivities. Trans Faraday Soe 52 299—310... 

Rosseinsky, D.R., Nicol, M.J., Kite, K., and Hill, R.J. (1974) Manganese(III) and its hydroxo- and chloro-complexes in aqueous perchloric acid comparison with similar transition-metal(III) complexes. J. Chem. Soc., Faraday Trans., 70, 2232-2238. 

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