Question

In a particular redox reaction, MnO₂ is oxidized to MnO and Cu²+ is reduced to Cut. Complete and balance the equation for

this reaction in acidic solution. Phases are optional.
balanced redox reaction:
MnO₂ + Cu²+ —>
MnO + Cu+

Answer 1

To balance the redox reaction in acidic solution, follow these steps:

Assign oxidation numbers to each element in the reaction:

Mn in MnO₂: +4

Mn in MnO: +2

Cu in Cu²⁺: +2

Cu in Cu⁺: +1

Identify the elements undergoing oxidation and reduction:

Oxidation: Mn in MnO₂ is going from +4 to +2.

Reduction: Cu²⁺ is going from +2 to +1.

Balance the number of atoms for each element except for H and O:

MnO₂ + Cu²⁺ → MnO + Cu⁺

Balance the oxygen atoms by adding water (H₂O) molecules:

MnO₂ + Cu²⁺ → MnO + Cu⁺ + H₂O

Balance the hydrogen atoms by adding hydrogen ions (H⁺):

MnO₂ + Cu²⁺ + 4H⁺ → MnO + Cu⁺ + 2H₂O

Balance the charge by adding electrons (e⁻):

MnO₂ + Cu²⁺ + 4H⁺ + 2e⁻ → MnO + Cu⁺ + 2H₂O

Make sure that the number of electrons lost in the oxidation half-reaction equals the number of electrons gained in the reduction half-reaction.

The balanced redox reaction in acidic solution is:

MnO₂ + Cu²⁺ + 4H⁺ → MnO + Cu⁺ + 2H₂O