Question

Explain the term disproportionation reaction.

Answer 1

Hint : Disproportionation reaction is a type of redox reaction. In this type of reaction a single reactant simultaneously undergoes oxidation as well as reduction. Two different products are formed, one by oxidation and second by reduction of the same reactant. This reaction is also known as the dismutation reaction.

Complete Step By Step Answer:
Disproportionation reaction is also known as dismutation reaction. In this type of reaction a single reactant undergoes oxidation as well as reduction. The reactant molecule itself acts as oxidizing as well as reducing agent.
So, we can say that, the reactant which is present in it’s intermediate oxidation state can undergo this type of reaction. This will produce two new different compounds one with higher oxidation state and the other one with lower oxidation state than the initial reactant.
We can better understand disproportionation reaction with the help of following examples:-
When ${H_3}P{O_3}$ is heated it shows disproportionation reaction, as the reaction is:-
In the above reaction, the oxidation state of P (phosphorus) in ${H_3}P{O_3}$ is $+ 3$ .
So, after the reaction, the oxidation state increases from $+ 3$ to $+ 5$ in ${H_3}P{O_4}$ while the oxidation state decreases from $+ 3$ to $- 3$ in $P{H_3}$ .
Another example is, disproportionation reaction of $C{l_2}$ when it reacts with ${H_2}O$ as follows:-
$C{l_2} + {H_2}O \to HCl + HOCl$
In the above reaction, the oxidation state of chlorine ( $Cl$ ) in $C{l_2}$ is $0$ .
So, after the reaction, the oxidation state of chlorine increases from $0$ to $+ 1$ in $HOCl$ while the oxidation state decreases from $0$ to $- 1$ in $HCl$ .
Therefore, the above mentioned reactions are examples of disproportionation reactions.

Note :
Some other types of redox reactions except disproportionation reactions are decomposition reaction, displacement reaction, combination reaction, etc. There is one more type of reaction which is opposite to the disproportionation reaction, in which the compounds in higher and lower oxidation states undergo a reaction to form compounds in intermediate oxidation states. This type of reaction is known as synproportionation or comproportionation reaction.