Question

In the following reaction
$Fe _{3} O _{4}+ MnO _{4}^{-} \longrightarrow Fe _{2} O _{3}+ MnO _{2}$
the number of moles of $OH ^{-}$liberated as per the balanced equation in the basic medium is

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (B)

$\therefore Fe _{3} O _{4}$ and $MnO _{4}^{-}$react in $6: 2$ mole ratio in the balanced chemical equation
$6 Fe _{3} O _{4}+2 MnO _{4}^{-}+ H _{2} O \longrightarrow 9 Fe _{2} O _{3}+2 MnO _{2}+ OH$
By balancing the residual charge with $OH ^{-}$
$6 Fe _{3} O _{4}+2 MnO _{4}^{-}+ H _{2} O \longrightarrow 9 Fe _{2} O _{3}+2 MnO _{2}+2 OH$