D-And F-Block Elements Ques 32
Question: $ KMnO_4 $ in basic medium is reduced to
[Orissa JEE 2005]
Options:
A) $ K_2MnO_4 $
B) $ MnO_2 $
C) $ Mn{{(OH)}_2} $
D) $ M{{n}^{2+}} $
Show Answer
Answer:
Correct Answer: B
Solution:
$ KMnO_4 $ is first reduced to manganate and then to insoluble manganese dioxide. Colour changes first from purple to green and finally becomes colourless.
$ 2KMnO_7+2KOH\to 2K_2MnO_4+H_2O+O $
$ 2K_2MnO_4+2H_2O\to 2MnO_2+4KOH+2O $
$ 2KMnO_2+H_2O\xrightarrow{alkaline}2MnO_2+2KOH+3[O] $
