Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: zaied9 on November 24, 2006, 12:30:53 PM
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I want to know :
Why do we use potassium permanganate in acidic media while oxidizing ferrous sulfate ?
and how will be the reaction in the neutral media and in the basic
plz i need the answer so soon and plz give me the reference name .
Thatnks all.
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In acidic media, permanganate oxidizes cleanly and quantitatively to Mn(2+) according to the following half-reaction:
MnO4(-) + 8H(+) + 5e ---> Mn(2+) + 4H2O
This reaction is fast and complete. The reaction product is (almost) colorless.
In neutral and basic solutions, permanganate oxidizes mainly to MnO2, but a certain part also can be reduced to Mn2O3 (hydrous form). A dark brown flocculent precipitate is formed with somewhat indeterminate composition, empirical formula is MnOx, with x close to 2, but usually slightly less (e.g. MnO1.95), with the precise value depending on the reductor, the precise pH and who knows what more conditions. Anyways, reduction of permanganate in neutral or basic media is much less clean and certainly not suitable for use in analytic chemistry.