Question

Complete the following reactions.
(i) $MnO_4^- + 2H_2O + 3e^- \to$ ___ + $4OH^-$
(ii) $MnO_4^- + 8H^+ + 5e^- \to$ ____ $+ 4H_2O$
(iii) $MnO_4^- + e^- \to$ ____

• A. $MnO_2$, $Mn^{2+}$, $MnO_4^{2-}$
• B. $Mn^{2+}$, $MnO_2$, $MnO^{2-}_4$
• C. $MnO^{2-}_4$, $Mn^{2+}$, $MnO_2$
• D. $MnO_2$, $MnO^{2-}_4$, $Mn^{2+}$

Answer 1

Answer: (A)

$MnO _{4}^{-}+2 H _{2} O +3 e ^{-} \rightarrow MnO _{2}+4 OH ^{-}$
$MnO _{4}^{-}+8 H ^{+}+5 e ^{-} \rightarrow Mn ^{2+}+4 H _{2} O$
$MnO _{4}^{-}+ e ^{-} \rightarrow MnO _{4}^{2-}$