Question

Identify the oxidizing agent (oxidant) in the following reactions:
(a)- $P{{b}_{3}}{{O}_{4}}+8HCl\to 3PbC{{l}_{2}}+C{{l}_{2}}+4{{H}_{2}}O$
(b)- $Mg+2{{H}_{2}}O\to Mg{{(OH)}_{2}}+{{H}_{2}}$
(c)- $CuS{{O}_{4}}+Zn\to Cu+ZnS{{O}_{4}}$
(d)- ${{V}_{2}}{{O}_{5}}+5Ca\to 2V+5CaO$

Answer 1

The oxidizing agent or the reducing agent in a reaction can be easily calculated by finding the oxidation number of the atoms in each reaction. The oxidized and reduced agents are the opposite of oxidizing and reducing agents.

Complete step by step answer:
The oxidation number of an element is defined as the charge on an atom of the element which it has in its ion or appears to have when it is in combined state with other atoms. We can also call the oxidation number as an oxidation state.
Oxidation is the process or a chemical change in which there is an increase in the oxidation number of an atom or atoms.
The reduction is the process or a chemical change in which there is a decrease in the oxidation number of an atom or atoms.
An oxidizing agent or an oxidant is a substance in which the oxidation number or state decreases.
A reducing agent or a reluctance is a substance in which the oxidation number or state increases.
So, in$P{{b}_{3}}{{O}_{4}}+8HCl\to 3PbC{{l}_{2}}+C{{l}_{2}}+4{{H}_{2}}O$, the oxidation number of Pb decreases from$+\dfrac{8}{3}$ to +2. Therefore, $P{{b}_{3}}{{O}_{4}}$is the oxidizing agent.
In, $Mg+2{{H}_{2}}O\to Mg{{(OH)}_{2}}+{{H}_{2}}$, the oxidation number of H decreases from +1 to 0. Therefore, ${{H}_{2}}O$ is the oxidizing agent.
In$CuS{{O}_{4}}+Zn\to Cu+ZnS{{O}_{4}}$, the oxidation number of Cu decreases from +2 to 0. Therefore, $CuS{{O}_{4}}$ is the oxidizing agent.
In, ${{V}_{2}}{{O}_{5}}+5Ca\to 2V+5CaO$, the oxidation number of V decreases from +5 to 0.

Therefore, ${{V}_{2}}{{O}_{5}}$ is the oxidizing agent.

Note: You may get confused that the substance which gets oxidized also acts as an oxidizing agent and the substance which gets reduced also acts as a reducing agent. But they are the opposite.