Question

In the following reaction $\underset{\mathrm{Bromine}}{3{\mathrm{Br}}_2\left(\mathrm{l}\right)}+\underset{\mathrm{Carbonate}\mathrm{ion}}{6{{\mathrm{CO}}_3}^{2-}}+\underset{\mathrm{water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\rightleftharpoons \underset{\mathrm{Bromide}\mathrm{ion}}{5{\mathrm{Br}}^{-}}+\underset{\mathrm{Bromate}\mathrm{ion}}{{{\mathrm{BrO}}_3}^{-}}+\underset{\mathrm{Bicarbonate}\mathrm{ion}}{6{{\mathrm{HCO}}_3}^{-}}$

• A. Bromine is oxidized and Carbonate is reduced.
• B. Bromine is reduced and Carbonate is oxidized
• C. Bromine is neither oxidized nor reduced
• D. Bromine is both oxidized and reduced.

Answer 1

The correct option is D

Bromine is both oxidized and reduced.

The explanation for the correct option:

Option(D): Bromine is both oxidized and reduced.

1. When both reduction and oxidation occur in the same substance, resulting in two products, and when the substance's oxidation state is oxidized and reduced into two half-reactions, resulting in two new compounds, a disproportionation reaction occurs.
2. In the given reaction oxidation of Bromine changes from $0$ to$+5$. Hence, oxidation of bromine occurs. $\underset{\mathrm{Bromine}}{\stackrel{0}{\mathrm{Br}\left(\mathrm{l}\right)}}\to \underset{\mathrm{Bromate}\mathrm{ion}}{\stackrel{+5}{{{\mathrm{BrO}}_3}^{-}}}$
3. Also, at the same time oxidation number of Bromine changes from $0$ to$-1$. Hence the reduction of Bromine occurs. $\stackrel{0}{\underset{\mathrm{Bomine}}{\mathrm{Br}\left(\mathrm{l}\right)}}\to \stackrel{-1}{\underset{\mathrm{Bromide}\mathrm{ion}}{{\mathrm{Br}}^{-}}}$
4. Hence, it is the correct option.

The explanation for incorrect option(s):

Option (A): Bromine is oxidized and carbonate is reduced.

1. In the given reaction along with the oxidation of Bromine its reduction also takes place that's why it is a disproportionate reaction.
2. Carbonate does not undergo reduction as its oxidation number is the same.
3. Hence it is an incorrect option.

Option (B): Bromine is reduced and carbonate is oxidized.

1. In the given reaction reduction of Carbonate does not undergo oxidation because its oxidation number remains the same.
2. Along with the reduction of Bromine, its oxidation also occur.
3. Hence it is an incorrect option.

Option (C): Bromine is neither oxidized nor reduced.

1. In the given reaction, oxidation and reduction of Bromine occur simultaneously therefore, it is a disproportionate reaction.
2. Hence it is an incorrect option.

Therefore, In the given reaction oxidation and reduction of bromine occurs.