Redox Reaction Chemistry Example 4

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Example 4

hard
Balance the following redox reaction in acidic solution using the half-reaction method: MnO4−+Fe2+→Mn2++Fe3+\text{MnO}_4^- + \text{Fe}^{2+} \rightarrow \text{Mn}^{2+} + \text{Fe}^{3+}.

Solution

  1. 1
    Reduction half-reaction: MnO4−→Mn2+\text{MnO}_4^- \rightarrow \text{Mn}^{2+}. Balance O with water: MnO4−→Mn2++4H2O\text{MnO}_4^- \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O}. Balance H with H+\text{H}^+: 8H++MnO4−→Mn2++4H2O8\text{H}^+ + \text{MnO}_4^- \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O}. Balance charge with electrons: 5e−+8H++MnO4−→Mn2++4H2O5e^- + 8\text{H}^+ + \text{MnO}_4^- \rightarrow \text{Mn}^{2+} + 4\text{H}_2\text{O}.
  2. 2
    Oxidation half-reaction: Fe2+→Fe3++e−\text{Fe}^{2+} \rightarrow \text{Fe}^{3+} + e^-. Multiply by 5 to balance electrons: 5Fe2+→5Fe3++5e−5\text{Fe}^{2+} \rightarrow 5\text{Fe}^{3+} + 5e^-.
  3. 3
    Add half-reactions: MnO4−+5Fe2++8H+→Mn2++5Fe3++4H2O\text{MnO}_4^- + 5\text{Fe}^{2+} + 8\text{H}^+ \rightarrow \text{Mn}^{2+} + 5\text{Fe}^{3+} + 4\text{H}_2\text{O}.

Answer

MnO4−+5Fe2++8H+→Mn2++5Fe3++4H2O\text{MnO}_4^- + 5\text{Fe}^{2+} + 8\text{H}^+ \rightarrow \text{Mn}^{2+} + 5\text{Fe}^{3+} + 4\text{H}_2\text{O}
The half-reaction method systematically balances redox equations by separating the oxidation and reduction processes, balancing each independently, then combining them so that electrons cancel. This is essential for complex redox reactions.

About Redox Reaction

A chemical reaction in which electrons are transferred from one substance (the reducing agent, which is oxidized) to another (the oxidizing agent, which is reduced).

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More Redox Reaction Examples

Example 1 easy

Define a redox reaction and explain the relationship between oxidation and reduction.

Example 2 medium

In the reaction [formula], identify the oxidizing agent and the reducing agent.

Example 3 medium

Determine whether the following reaction is a redox reaction: [formula]. Justify your answer.

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