Q52 / 180 · COMEDK 2021 · Chemistry
For decolourisation of 1 mole of $\mathrm{KMnO}_{4}$, the moles of $\mathrm{H}_{2} \mathrm{O}_{2}$ required is
- A$\dfrac{1}{2}$
- B$\dfrac{3}{2}$
- Correct answerC$\dfrac{5}{2}$
- D$\dfrac{7}{2}$
Solution
The redox reaction between potassium permanganate and hydrogen peroxide in an acidic medium is given by the following balanced chemical equation:
2KMnO$_{4}$ + 3H$_{2}$SO$_{4}$ + 5H$_{2}$O$_{2}$ $\rightarrow$ K$_{2}$SO$_{4}$ + 2MnSO$_{4}$ + 8H$_{2}$O + 5O$_{2}$
From the stoichiometry of the balanced equation, 2 moles of KMnO$_{4}$ react with 5 moles of H$_{2}$O$_{2}$.
Therefore, for 1 mole of KMnO$_{4}$, the moles of H$_{2}$O$_{2}$ required is $\dfrac{5}{2}$.
Answer: $\dfrac{5}{2}$
2KMnO$_{4}$ + 3H$_{2}$SO$_{4}$ + 5H$_{2}$O$_{2}$ $\rightarrow$ K$_{2}$SO$_{4}$ + 2MnSO$_{4}$ + 8H$_{2}$O + 5O$_{2}$
From the stoichiometry of the balanced equation, 2 moles of KMnO$_{4}$ react with 5 moles of H$_{2}$O$_{2}$.
Therefore, for 1 mole of KMnO$_{4}$, the moles of H$_{2}$O$_{2}$ required is $\dfrac{5}{2}$.
Answer: $\dfrac{5}{2}$
Hence, the correct answer is option: 'C'.