Balancing Redox Reactions - Free MCQ Practice Test with solutions, NEET

As it is given that this reaction is in acidic medium, that means we have H+ on the reactant side so to balance Oxygen we have to add water on the product side instead of adding just Oxygen.

Option D is correct. The oxidation half-reaction is Fe²⁺ → Fe³⁺ + e^-.

Oxidation means an increase in oxidation number. Here the oxidation number of iron changes from +2 to +3, which is an increase by 1, so iron loses one electron.

Showing the electron explicitly gives the balanced oxidation half-reaction: Fe²⁺(aq) → Fe³⁺(aq) + e^-.

This identifies iron as the species being oxidised and confirms that option D is the correct oxidation half-reaction.

In the ion-electron method (also called the half-reaction method), the redox equation is separated into two half-equations - one for oxidation and one for reduction. Each of these half-reactions is balanced separately and then combined to give the balanced redox equation.

A titration is a technique used to work out the concentration of an unknown solution based on its chemical reaction with a solution of known concentration. The process usually involves adding the known solution (the titrant) to a known quantity of the unknown solution (the analyte) until the reaction is complete.

Step 1: Identify the oxidation and reduction half-reactions.
  Reduction half-reaction: MnO₄^– → Mn²⁺
  Oxidation half-reaction: C₂O₄^2- → CO₂
Step 2: Balance each half-reaction.
  Reduction half-reaction:
   MnO₄^– + 8H⁺ + 5e^– → Mn²⁺ + 4H₂O
  Oxidation half-reaction:
   C₂O₄^2- → 2CO₂ + 2e^–
Step 3: Equalize the number of electrons by multiplying the half-reactions accordingly.
  Multiply oxidation half-reaction by 5:
   5C₂O₄^2- → 10CO₂ + 10e^–
  Multiply reduction half-reaction by 2:
   2MnO₄^– + 16H⁺ + 10e^– → 2Mn²⁺ + 8H₂O
Step 4: Add the two balanced half-reactions to get the overall balanced equation.
  2MnO₄^– + 16H⁺ + 5C₂O₄^2- → 2Mn²⁺ + 10CO₂ + 8H₂O
Conclusion: The correct coefficients of the reactants are: MnO₄^– = 2, C₂O₄^2- = 5, H⁺ = 16.