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Polarizations, manganese dioxide

As shown in Fig. 8, three types of polarization exist during the discharge of porous MnOa. The battery active EMD or CMD (chemical manganese dioxide) is highly porous and the concentration polarization due to the pH change, r (ApH), is very important. Kozawa studied the three types of... [Pg.118]

In alkaline Mn02-Zn systems the same electrochemically active materials, manganese dioxide and zinc, are used as in Leclanche cells. The only difference to the latter system is the cathode sleeve construction and the highly conductive KOH electrolyte (7 M 0.55 (Ocm)-l) as already mentioned. The anode is formed of zinc powder instead of a zinc can. Electrolytic manganese dioxide is used for the cathode material. Due to its low polarization and high voltage characteristic it performs far better than chemically produced manganese dioxide or natural ore. [Pg.167]

Polar solvents inhibit the reaction, presumably by interfering with the adsorption process as noted in the mechanism proposed for manganese dioxide oxidations. Oxidation of 1-heptanol to heptanal with Fetizon s reagent was quantitative when the solvent was 35% hexanes. When benzene was used as a solvent, the yield of heptanal dropped to 90% and was < 1% in ethyl acetate, methyl ethyl ketone, or acetonitrile. 69 Since the oxidation is a heterogeneous reaction, requiring adsorption of the alcohol substrate, as the surface area of the reagent increases (increased by precipitation on Celite), the rate of oxidation increases. An optimum ratio is reached beyond which increasing the silver carbonate/Celite ratio slows the oxidation. 69... [Pg.217]

Leclanche cell A primary voltaic cell consisting of a carbon rod (the anode) and a zinc rod (the cathode) dipping into an electrolyte of a 10-20% solution of ammonium chloride. Polarization is prevented by using a mixture of manganese dioxide mixed with crashed carbon, held in contact with the anode by means ofaporousbagorpot this reacts with the hydrogen produced. This wet form of the cell, devised in 1867 by Georges Leclanchfi (1839-82), has an e.m.f. of about... [Pg.472]

Katsoulis, D. E. Taush, V. S. Pope, M. T., Interaction of Sulfur Dioxide with Heteropolyanions in Nonpolar Solvents. Evidence for Complex Formation, Inorg. Chem. 1987, 26, 215. (d) Katsoulis, D. E Pope, M. T. Reactions of Heteropolyanions in Non-Polar Solvents. 3. Activation of Dioxygen by Manganese(ll) Centers in Polytungstates - Oxidation of Hindered Phenols,/. Chem. Soc. Dalton Trans. 1989, 1483. [Pg.214]


See other pages where Polarizations, manganese dioxide is mentioned: [Pg.614]    [Pg.614]    [Pg.526]    [Pg.244]    [Pg.246]    [Pg.442]    [Pg.1034]    [Pg.314]    [Pg.131]    [Pg.132]    [Pg.106]    [Pg.738]    [Pg.738]    [Pg.106]    [Pg.443]    [Pg.3131]    [Pg.521]    [Pg.525]    [Pg.526]    [Pg.313]    [Pg.267]    [Pg.305]    [Pg.738]    [Pg.75]    [Pg.728]    [Pg.194]    [Pg.244]    [Pg.251]    [Pg.1181]    [Pg.1322]    [Pg.341]    [Pg.131]    [Pg.52]    [Pg.56]    [Pg.179]    [Pg.222]    [Pg.509]    [Pg.503]   
See also in sourсe #XX -- [ Pg.118 ]




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