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Oxides on anode

Phosphates, molybdates, and (at high pH) silicates act as anodic inhibitors much as do alkalis, except that the iron oxides/hydroxides formed on anodic sites then contain some PO43-, M0O42-, or Si044- ( basic iron phosphates, etc.). These inhibitors require the presence of 02 to produce basic iron(III) phosphate, molybdate, or silicate films, whereas oxidizing anions such as chromates and nitrites oxidize Fe2+ (aq) rapidly to insoluble iron(III) oxides on anodic sites. Dianodic inhibitors combine complementary inhibition mechanisms for example, sodium triphosphate may be used with sodium chromate, or sodium molybdate with NaN02. [Pg.349]

It is easy to do this if the electrode is a noble metal, he., does not itself easily oxidize on anodic polarization. One evolves H2 cathodically until the entire surface is covered with H atoms (0H =1) and then reverses the direction of the current, making it anodic and dissolving the adsorbed H atoms (MH —> M + H + e). It is easy, by use of a cathode ray oscillograph, to record the i,-t relation during dissolution at a constant potential. Apart from an initial charging potential, one obtains the coulombs used in... [Pg.378]


See other pages where Oxides on anode is mentioned: [Pg.899]   
See also in sourсe #XX -- [ Pg.478 ]




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