Electrode lead

If the charging process continues after all the lead sulphate has been used up, then the charging voltage rises. Hydrogen is liberated from the lead electrode, and oxygen is liberated from the lead dioxide electrode. The accumulator is then said to be gassing . 

Alternatively, hydroxylammonium salts can be made either (a) by the electrolytic reduction of aqueous nitric acid between amalgamated lead electrodes in the presence of H2SO4/HCI, or (b) by the hydrogenation of nitric oxide in acid solutions over a Pl/charcoal catalyst ... 

Pavlov, D. and Rogachev, T. Dependence of the Phase Composition of The Anodic Layer on Oxygen Evolution and Anodic Corrosion of Lead Electrode in Lead Dioxide Potential Region , Electrochim. Acta., 23, 1237 (1978)... 

The lead electrode used as anode in the well-known lead-acid battery is a rather... 

Indeed a detailed kinetic investigation of the reduction of alkyl iodides at a lead electrode in dimethylformamide shows that the process is complex and involves catalysis by a lead alkyl species at the surface (Fleischmann et al., 1971a). The catalytic cycle proposed was... 

Electrons appear as products, so this half-reaction is the oxidation, which takes place at the anode. The lead electrode is an active anode in a lead storage battery. 

Yang YJ, He LY (2006) Dissolution of lead electrode and preparation of rod-shaped PbS crystals in a novel galvanic ceU. J Solid State Electrochem 10 430-433... 

The best known example is the electrosynthesis of tetraethyllead (TEL) Pb(C2Hj)4, which has been in wide use as an antiknock additive of gasoline, and still is in a number of countries. This substance is readily produced by reaction of ethyl radicals with the lead electrode ... 

As a switching device capable for ultra-large-scale integrated circuits (ULSIs) comprises only one Coulomb island with two leads (electrodes) and a capacitively coupled gate electrode attached to it. This system works as a simple on/off switch and it is often called the SE transistor. Applying a voltage to the outer electrodes of this circuit may either cause sequential transfer of electrons onto and out of the central island or to have no charge transport, i.e. the transistor remains in non-conductive state. The result... 

Fig. 5.52 Pb02 dendrite growth at a lead electrode. Current density 0.3 mA cm-2. (From G. Wranglen, Electrochim. Acta, 2, 130, 1960)... 

An example of dimerization of the intermediates of an electrode reaction is provided by the reduction of acrylonitrile in a sufficiently concentrated aqueous solution of tetraethylammonium p-toluene sulphonate at a mercury or lead electrode. The intermediate in the reaction is probably the dianion... 

The term regulated battery means a rechargeable battery that (a) contains a cadmium or a lead electrode or any combination of cadmium and lead electrodes or (b) contains other electrode... 

The lead storage cell (six of which make up the lead storage battery commonly used in automobiles) will be discussed as an example of a practical cell. The cell, pictured in Fig. 14-2, consists of a lead electrode and a lead dioxide electrode immersed in relatively concentrated H2S04 in a single container. When the cell delivers power (when it is used), the electrodes react as follows ... 

A little later, Russell et al.19 tried to obtain methanol from carbon dioxide by electrolysis. Reduction of carbon dioxide to formate ion took place in a neutral electrolyte at a mercury electrode. On the other hand, formic acid was reduced to methanol either in a perchloric acid solution at a lead electrode or in a buffered formic acid solution at a tin electrode. The largest faradaic efficiency for methanol formation from formic acid was ca. 12%, with poor reproducibility, after passing 1900 C in the perchloric acid solution at Pb in a very narrow potential region (-0.9 to -1.0 V versus SCE). In the buffered formic acid solution (0.25 M HCOOH + 0.1 M... 

Electrochemical synthesis was utilized to prepare labeled compounds. Tetramethyllead labeled with 14C was prepared in a double compartment cell in DMF with NaClC>4, by electrolyzing 14CH3l on lead electrodes. The method is reported as superior to transmet-allation with methylmagnesium halide. It is also possible to incorporate lead isotopes. 2i°Pb2+ ions were deposited on a Cu foil and the latter was used as a sacrificial electrode in solutions of CH3I. The yield of labeled tetramethyllead was 85%65. Synthesis of 210Pb-labeled chlorotrimethylplumbane was also described66. 

Ziegler (2) A process proposed for making tetraethyl lead by electrolyzing the molten complex of ethyl potassium with triethyl aluminum, KA1(C2H5)4, using a lead electrode. Invented in 1963 by K. Ziegler and H. Lehmkiihl but not commercialized. 

Leaded zinc oxide, 26 613 Lead electrodes, 3 408, 430 Leaders, R D, 21 621 Lead fluoride, 14 784... 

Figure 7 Differential tunneling spectrum of CO chemisorbed on alumina supported rhodium particles. Peak positions are not corrected for possible shifts due to the top lead electrode. Peak positions vary with rhodium coverage and CO exposure.

The reaction was investigated under a variety of conditions. As noted in Table 2, both the yield and stereo-selectivity varied in response to changes in the electrode and proton donor (HD). Environmental factors clearly make the use of a glassy carbon electrode preferable to mercury or lead electrodes. Yields range from 58 to 87%, and the stereo-selectivity from a low of 2.6 1 trans/cis (6a/6b) to as high as 14.8 1 when the reaction is conducted in the presence of cerium (III) chloride. 

In activated sludge, 80.6% degraded after a 47-h time period (Pal et al., 1980). Chemical/Physical. Zhang and Rusling (1993) evaluated the bicontinuous microemulsion of surfactant/oil/water as a medium for the dechlorination of polychlorinated biphenyls by electrochemical catalytic reduction. The microemulsion (20 mL) contained didodecyldi-methylammonium bromide, dodecane, and water at 21, 57, and 22 wt %, respectively. The catalyst used was zinc phthalocyanine (2.5 nM). When PCB-1221 (72 mg), the emulsion and catalyst were subjected to a current of mA/cm on 11.2 cm lead electrode for 10 h, a dechlorination yield of 99% was achieved. Reaction products included a monochlorobiphenyl (0.9 mg), biphenyl, and reduced alkylbenzene derivatives. 

In keto steroids the reductions were also achieved by electrolysis in 10% sulfuric acid and dioxane using a divided cell with lead electrodes (yields 85-97%) [862], hy specially activated zinc dust in anhydrous solvent (ether or acetic anhydride saturated with hydrogen chloride) (yields 50-87%) [155, 86J], and by the above mentioned reduction of tosylhydrazones with sodium borohydride (yields 60-75%) [811]. 

Aliphatic alcohols are not reducible under electrochemical conditions. Conversion to a suitable anionic leaving group however does allow carbon-oxygen bond cleavage. Thus, methanesulphonates are reduced at a lead electrode under constent current conditions and this affords an overall tw o step process for the conversion of alcohols to alkanes [9].Deoxygenation of alcohols by this route has been applied successMly in the presence of other functional groups which are difficult to reduce such as alkene, epoxide, ester and nitrile. Cyclopropanes are formed in 50-97 %... 

The main properties of the double layer of solid lead electrodes have been already described in the Encyclopedia [1]. New achievements in this field have been the subject of reviews [for example [2-6]. Some of the new results relate to impedance of polycrystalline Pb electrodes in aqueous [7-9] and nonaqueous solvents (references in [3, 6[). Special attention has been paid to chemically and electrochemically polished polycrystalline electrodes, mainly in aqueous [10-12] and methanolic [13] fluoride solutions. 

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