Question

KMnO₄ can be prepared from K₂MnO₄ as per the reaction:
\(3MnO^{2-}_4+2H_2O⇌2MnO^-_4+MnO_2+4OH^-\)
The reaction can go to completion by removing OH^- ions by adding

• A. HCl
• B. KOH
• C. CO₂
• D. SO₂

Answer 1

The Correct Option is C

To determine which substance can be used to drive the reaction towards completion by removing OH^- ions, let's analyze the chemical reaction:

\(3MnO^{2-}_4 + 2H_2O ⇌ 2MnO^-_4 + MnO_2 + 4OH^-\)

From the reaction, it is clear that hydroxide ions (OH^-) are produced as a product. To shift the equilibrium to the right and drive the reaction to completion, we must remove OH^- ions from the solution. This can be achieved by adding a substance that reacts with OH^- ions effectively.

Let's evaluate the options:

1. HCl: Hydrochloric acid will react with OH^- ions to form water (H₂O), but the resulting solution remains in a relatively inert state and might not efficiently shift the equilibrium in the desired direction.
2. KOH: Adding potassium hydroxide would increase the concentration of OH^- ions instead of removing them, pushing the reaction in the opposite direction.
3. CO₂: Carbon dioxide in water forms carbonic acid (H₂CO₃), which will react with OH^- to form bicarbonate (HCO₃^-):

\(CO_2 + 2OH^- ⇌ H_2O + CO_3^{2-}\)

This reaction effectively removes OH^- ions from the solution, thereby favoring the forward reaction.

4. SO₂: While sulfur dioxide can react with OH^- ions, it is less efficient than CO₂ at shifting this particular equilibrium.

Therefore, the correct answer is CO₂ as it effectively removes OH^- ions and drives the reaction to completion.