Question

Balance the following equation:

${MnO}_4^{-}\to M{n}^{2+}+H_{2}O$

• A. ${MnO}_4^{-}+8H^{+}+5e\to M{n}^{2+}+4H_{2}O$
• B. ${MnO}_4^{-}+8H^{+}+3e\to M{n}^{2+}+4H_{2}O$
• C. ${MnO}_4^{-}+4H^{+}+5e\to M{n}^{2+}+4H_{2}O$
• D. None of these

Answer 1

The correct option is A ${MnO}_4^{-}+8H^{+}+5e\to M{n}^{2+}+4H_{2}O$

The unbalanced redox equation is as follows:
${MnO}_4^{-}\to M{n}^{2+}+H_{2}O$
All atoms other than H and O are balanced.
O atoms are balanced by adding 3 water molecules on RHS..
${MnO}_4^{-}\to M{n}^{2+}+4H_{2}O$
Hydrogen atoms are balanced by adding 8 $H^{+}$ ions on the RHS.
${MnO}_4^{-}+8H^{+}\to M{n}^{2+}+4H_{2}O$
Balance the charges by adding 5 electrons on the LHS.
${MnO}_4^{-}+8H^{+}+5e^{-}\to M{n}^{2+}+4H_{2}O$
This is the balanced chemical equation.