Question

Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below :

Then the species undergoing disproportionation is

• A. \(\text{BrO}^{-}_3\)
• B. \(\text{Br}_2\)
• C. \(\text{BrO}_4^{-}\)/div>
• D. HBrO

Answer 1

The Correct Option is D

To determine the species undergoing disproportionation, we need to identify a species that can simultaneously undergo oxidation and reduction. Let's analyze the given species and their corresponding emf values:

1. Disproportionation is a special type of redox reaction where a single substance undergoes oxidation and reduction simultaneously. This generally happens when the intermediate oxidation state is unstable.
2. Review the emf values given for the reactions:
   • \(\text{BrO}_4^{-} \rightarrow \text{BrO}_3^{-}\) : 1.82 V
   • \(\text{BrO}_3^{-} \rightarrow \text{HBrO}\) : 1.5 V
   • \(\text{HBrO} \rightarrow \text{Br}_2\) : 1.595 V
   • \(\text{Br}_2 \rightarrow \text{Br}^-\) : 1.0652 V
3. Examining these values, \(\text{HBrO}\) is likely to undergo disproportionation because:
   • Given the reaction: \(\text{HBrO} \rightarrow \text{Br}_2\) is 1.595 V and \(\text{HBrO} \rightarrow \text{Br}^-\) implies \(\text{HBrO}\) can undergo both oxidation to form \(\text{Br}_2\) and reduction to yield \(\text{Br}^-\).
   • There is a positive emf value for both possible reactions, suggesting both processes are thermodynamically favorable.
4. In conclusion, \(\text{HBrO}\) undergoes disproportionation due to its ability to exist in intermediate and then go into higher (\(\text{Br}_2\)) and lower (\(\text{Br}^-\)) oxidation states simultaneously.

Therefore, the correct answer is:

HBrO