COMEDK202510 May 2025Morning ShiftChemistryRedox ReactionsActual
The concentration and percentage purity of Oxalic acid can be determined by titration with KMnO ₄ in presence of dil. H ₂ SO ₄ . Instead of dil. H ₂ SO ₄ , dil HCl cannot be used because
Options
- AHCl can also oxidise Oxalic acid to CO ₂ and H ₂ O .
- BOxalic acid oxidises HCl to Cl ₂ .
- CHCl can also reduce MnO ₄⁻ to Mn ²⁺
- DHCl can also provide H ⁺ ions in addition to H ⁺ ions from Oxalic acid.
Correct answer
C. HCl can also reduce MnO ₄⁻ to Mn ²⁺
Step-by-step solution
The titration of oxalic acid with potassium permanganate ( KMnO ₄ ) is performed in an acidic medium to ensure the reduction of MnO ₄⁻ to Mn ²⁺ . The balanced chemical equation for the reaction is: 5 H ₂ C ₂ O ₄ + 2 MnO ₄⁻ + 6 H ⁺ 10 CO ₂ + 2 Mn ²⁺ + 8 H ₂ O . Dilute sulfuric acid ( H ₂ SO ₄ ) is used because it is a non-oxidizing acid and provides the necessary H ⁺ ions without interfering with the redox reaction. If dilute hydrochloric acid ( HCl ) is used, the chloride ions ( Cl ⁻ ) present in the solution act a