Permanganate ion, as oxidant

Perhaps even more important is the effect of hydrogen ion concentration on the emf of a half-reaction of a particular species. Consider the permanganate ion as an oxidizing agent in acid solution (as it often is). From the Latimer diagram above we can readily see that the reduction emf is 1.51 V when all species have unit activity. What is not shown is the complete equation ... 

For an electrode containing a conventional oxidation-reduction system, terms are included in both numerator and denominator of equation (45.15). For example, if the system is manganous-permanganate ions, as ven in 45a, the expression for the electrode potential is... 

The purple permanganate ion [14333-13-2], MnOu can be obtained from lower valent manganese compounds by a wide variety of reactions, eg, from manganese metal by anodic oxidation from Mn(II) solution by oxidants such as o2one, periodate, bismuthate, and persulfate (using Ag" as catalyst), lead peroxide in acid, or chlorine in base or from MnO by disproportionation, or chemical or electrochemical oxidation. 

Oxidizing agents also attack the double bond. When a reaction between an unsaturated compound and the permanganate ion occurs, the violet color of permanganate fades. This reaction, as well as reaction (29b) in which a color change also occurs, is used as a qualitative test for the presence of double bonds in compounds. 

Ceric ammonium nitrate is used as a volumetric oxidizing reagent in many oxidation-reduction titrations. Cerium(IV) ion is a strong oxidant simdar to permanganate ion. It is the most widely-used primary standard among all Ce(IV) compounds. Other apphcations of this compound are in organic oxidation reactions and as a catalyst in polymerization of olefins. 

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