Some Basic Concepts of Chemistry 2 Question 1
1. An example of a disproportionation reaction is
(2019 Main, 12 April I)
(a) $2 \mathrm{MnO}{4}^{-}+10 \mathrm{I}^{-}+16 \mathrm{H}^{+} \longrightarrow 2 \mathrm{Mn}^{2+}+5 \mathrm{I}{2}+8 \mathrm{H}_{2} \mathrm{O}$
(b) $2 \mathrm{NaBr}+\mathrm{Cl}{2} \longrightarrow 2 \mathrm{NaCl}+\mathrm{Br}{2}$
(c) $2 \mathrm{KMnO}{4} \longrightarrow \mathrm{K}{2} \mathrm{MnO}{4}+\mathrm{MnO}{2}+\mathrm{O}_{2}$
(d) $2 \mathrm{CuBr} \longrightarrow \mathrm{CuBr}_{2}+\mathrm{Cu}$
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Solution:
- In disproportionation reactions, same element undergoes oxidation as well as reduction.
e.g.
Here, $\mathrm{CuBr}$ get oxidised to $\mathrm{CuBr}_{2}$ and also it get reduced to $\mathrm{Cu}$. Other given reactions and their types are given below.
In the given reaction, $\mathrm{MnO}{4}^{-}$get oxidised to $\mathrm{Mn}^{2+}$ and $\mathrm{I}^{-}$get reduced to $\mathrm{I}{2}$. It is an example of redox reaction. The reaction takes place in acidic medium.
$$ 2 \mathrm{KMnO}{4} \longrightarrow \mathrm{K}{2} \mathrm{MnO}{4}+\mathrm{MnO}{2}+\mathrm{O}_{2} $$
The given reaction is an example of decomposition reaction. Here, one compound split into two or more simpler compounds, atleast one of which must be in elemental form.
$$ 2 \mathrm{NaBr}+\mathrm{Cl}{2} \longrightarrow 2 \mathrm{NaCl}+\mathrm{Br}{2} $$
The given reaction is an example of displacement reaction. In this reaction, an atom (or ion) replaces the ion (or atom) of another element from a compound.
