Q4.61P - Chemistry: Molecular Nature Of Matter And Change

Question

Why must every redox reaction involve an oxidizing agent and a reducing agent?

Step-by-Step Solution

Answer

Answer:

Every redox reaction involves an oxidizing agent and a reducing agent. In a redox reaction simultaneous oxidation and reduction takes place. One of the species gets oxidized while the other one gets reduced. The species that accept electrons gets reduced and is known as the oxidizing agent. While the species that loses electron gets oxidized and is known as the reducing agent. Since both gain and loss of electrons happens so redox reactions involve both oxidizing and reducing agent.

Step 1: Definition of oxidizing agent

An oxidizing agent oxidizes other element and itself gets reduced in a chemical reaction.

Step 2: Definition of reducing agent

A reducing agent reduces other element and itself gets oxidized in a chemical reaction.

Step 3: Determine oxidizing and reducing agent in redox reaction

A redox reaction can be written as:

$\mathrm{A}+\mathrm{B}\to {\mathrm{A}}^{+}+{\mathrm{B}}^{-}$

 

Now the half reactions are:

$\mathrm{A}\to {\mathrm{A}}^{+}+{\mathrm{e}}^{-}$

$\mathrm{B}+{\mathrm{e}}^{-}\to {\mathrm{B}}^{-}$

 

Here, A is getting oxidized and its oxidation state changes from 0 to +1.

And, B is getting reduced and its oxidation state changes from 0 to -1.

Hence, B acts as an oxidizing agent. By accepting electrons, B gets reduced and oxidizes A. Electrons lost by A is gained by oxidizing agent B.

Step 4: Determine redox reaction contains oxidizing or reducing agent

In a redox reaction, there is a transfer of electron between species.

Electron lost by a reducing agent is gained by an oxidizing agent.

An oxidizing agent oxidizes other element and itself gets reduced in a chemical reaction.

A reducing agent reduces other element and itself gets oxidized in a chemical reaction.

That’s why a redox reaction involves both the oxidizing and reducing agent.