Home › MCQs › EEJ MAIN Chemistry › Question #7533
Back to Questions
EEJ MAIN Chemistry QUESTION #7533
Question 1

Hydrogen peroxide oxidizes $[\text{Fe(CN)}_6]^{4-}$ to $[\text{Fe(CN)}_6]^{3-}$ in acidic medium, and reduces $[\text{Fe(CN)}_6]^{3-}$ to $[\text{Fe(CN)}_6]^{4-}$ in alkaline medium. What are the other products formed in these two reactions, respectively?

  • H$_2$O and (H$_2$O + O$_2$)
  • H$_2$O and (H$_2$O + OH$^-$)
  • (H$_2$O + O$_2$) and H$_2$O✔️
  • (H$_2$O + O$_2$) and (H$_2$O + OH$^-$)
Correct Answer Explanation

Acidic medium (oxidising agent):
$[\text{Fe(CN)}_6]^{4-} + H_2O_2 + 2H^+ \to [\text{Fe(CN)}_6]^{3-} + \text{H}_2\text{O}$
H$_2$O$_2$ is reduced to H$_2$O. Other product: H$_2$O.

Alkaline medium (reducing agent):
$H_2O_2 \to H_2O + \frac{1}{2}O_2$ (H$_2$O$_2$ is oxidized)
$2[\text{Fe(CN)}_6]^{3-} + H_2O_2 + 2OH^- \to 2[\text{Fe(CN)}_6]^{4-} + O_2 + 2H_2O$
Other products: H$_2$O and O$_2$.

So the pair is: H$_2$O (acidic) and (H$_2$O + O$_2$) (alkaline).