Why does manganate need to be acidified? Watch

KanKan
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#1
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Looking at the reactions of potassium manganate as an oxidising agent, why does it need to be in the presence of some acid?
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charco
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(Original post by KanKan)
Looking at the reactions of potassium manganate as an oxidising agent, why does it need to be in the presence of some acid?
It doesn't.

It will act as an oxidising agent in the presence of base as well, however the reactions are different as its electrode potential is pH dependent...
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Godzilla123
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MnO4-is the most stable form of Mn(VII). If you think of Mn(VII) as having +7 charge, it would want as much negative oxygen as possible to stabilise the high positive charge. If you put acid, it gradually starts favouring protonation of the oxygens, which can possibly depart as H2O. Now, if they do that, you'll have less oxygens and less negative charge on the anion. Therefore, Mn(VII) is destabilised and even more willing to accept electrons. Thus, Mn(VII) is a better oxidising agent in acid. However, it can act as such in any medium. Hope that helped a little.
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Borek
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Rule of thumb: in alkaline solutions, MnO4- is reduced to MnO42-, in neutral solutions to MnO42-, in acidic solutions to Mn2+.
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KanKan
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Hmm, thanks all, it's starting to make more sense now
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