Question

Which one of the following acts as an autocatalyst during titration of \( KMnO_4 \) and oxalic acid in presence of dilute \( H_2SO_4 \)?

• A. \( H_2SO_4 \)
• B. \( KMnO_4 \)
• C. \( H_2C_2O_4 \)
• D. \( MnSO_4 \)

Hint:

Autocatalysis occurs when a reaction product enhances its own rate. In KMnO\(_4\)-oxalic acid titration, Mn\(^{2+}\) ions act as an autocatalyst.

Answer 1

The Correct Option is D

Step 1: Understanding Autocatalysis in KMnO\(_4\) Titration An autocatalyst is a product of a reaction that enhances its own rate as it forms. In the titration of potassium permanganate (\( KMnO_4 \)) with oxalic acid (\( H_2C_2O_4 \)) in acidic medium, the reaction initially proceeds slowly. However, as the reaction progresses, the formation of Mn\(^{2+}\) ions significantly increases the reaction rate. Step 2: Role of MnSO\(_4\) During the reaction: \[ 2MnO_4^- + 5C_2O_4^{2-} + 16H^+ \longrightarrow 2Mn^{2+} + 10CO_2 + 8H_2O \] - The Mn\(^{2+}\) ions (present in MnSO\(_4\)) act as a catalyst, accelerating the reaction. - Initially, the reaction is slow, but as Mn\(^{2+}\) ions accumulate, they enhance the rate, exhibiting autocatalytic behavior. Conclusion Thus, the correct answer is: \[ MnSO_4 \]