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  4. In the electrosynthesis, potassium manganate (VII) is converted to manganese (IV) dioxide. By passage of 1 F of electrolysis, one mole of potassium manganate (VII) will form manganese dioxide.

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Q. In the electrosynthesis, potassium manganate (VII) is converted to manganese (IV) dioxide. By passage of $1 F$ of electrolysis, one mole of potassium manganate (VII) will form manganese dioxide.

Electrochemistry

Solution:

Manganate (VII) is $MnO _{4}^{-}$ with oxidation number of $Mn =+7$

$\underset{1 mol }{ MnO _{4}^{-}}+3 e ^{-} \longrightarrow \underset{+4}{ MnO _{2}}$

1 mole required $3 F$ of electricity thus, $1 F$ will reduce only $(1 / 3)$ mole $MnO _{4}^{-}$ to $MnO _{2}$

Thus, $MnO _{2}$ formed $=0.33\, mol$.