How do #"MnO"_2# and #"KMnO"_4# behave? Oxidizing or reducing agents?

1 Answer
anor277
Dec 14, 2016

#"Manganese (IV) oxide"# and #KMnO_4# are #"oxidizing agents."#

Explanation:

#Mn^(2+)# is the reduction product. Because this is a #d^5# high spin metal centre, its electronic transitions are spin-forbidden, and a solution of #Mn^(2+)# is (almost!) completely colourless (very conc. solutions are a pale rose).

So, when we take strongly oxidizing permanganate ion, which is very strongly coloured, the redox reaction has a self-indicating end-point, and decolorizes:

#MnO_4^(-) +8H^(+) + 5e^(-) rarr Mn^(2+) +4H_2O#

We habitually use this reaction in redox titrations.

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