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Consider the standard volumetric titrations of oxalic acid and Mohr's salt (FAS) against KMnO ₄ in an acidic medium. Which of the following statements is INCORRECT?

Options

  1. AHeating is avoided in the titration of FAS to prevent the aerial oxidation of Fe ²⁺ ions.
  2. BThe titration of oxalic acid is auto-catalyzed by the Mn ²⁺ ions formed during the reaction.
  3. CThe central metal atom in the permanganate ion undergoes a change in oxidation state of 5 during these titrati
  4. DThe auto-catalyst responsible for speeding up the oxalic acid titration is produced by the oxidation of the pe

Correct answer

D. The auto-catalyst responsible for speeding up the oxalic acid titration is produced by the oxidation of the pe

Step-by-step solution

Evaluate each statement individually. Statement 1 is true: Heating Mohr's salt (FAS) causes the Fe ²⁺ ions to be oxidized to Fe ³⁺ by atmospheric oxygen, which introduces an error in the titration. Statement 2 is true: The reaction between oxalic acid and KMnO ₄ is initially slow but speeds up due to the formation of Mn ²⁺ ions, which act as an auto-catalyst. Statement 3 is true: In an acidic medium, the permanganate ion ( MnO ₄⁻ ) is reduced to Mn ²⁺ . The oxidation state of manganese changes from +7 to +2 , which

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