Question

Identify the reducing agent and oxidizing agent in the following reactions:

${\mathrm{V}}_2{\mathrm{O}}_5+5\mathrm{Ca}\to 2\mathrm{V}+5\mathrm{CaO}$

Answer 1

1. Redox reactions

A reaction between an oxidizing agent and a reducing agent can be called a redox reaction as it involves both oxidation and reduction. The change in the oxidation state of a species during the redox reaction can be determined to identify the oxidizing and reducing agents in the reaction.

Oxidation reactions involve the removal of electrons and therefore, an increase in the oxidation state. The reactant that undergoes oxidation is called the reducing agent. Reduction involves the addition of electrons and therefore, a decrease in the oxidation state. The reactant that undergoes reduction is the oxidizing agent.

2. Identifying oxidizing and reducing agents

$$\begin{gathered} {\mathrm{V}}_2{\mathrm{O}}_5\left(\mathrm{s}\right)+5\mathrm{Ca}\left(\mathrm{s}\right)\to 2\mathrm{V}\left(\mathrm{s}\right)+5\mathrm{CaO}\left(\mathrm{s}\right) \\ \mathrm{Vanadium}\mathrm{Calcium}\mathrm{Vanadium}\mathrm{Calcium} \\ \mathrm{pentoxide}\mathrm{oxide} \end{gathered}$$

The oxidation state of Calcium increases from 0 in Calcium $\left(\mathrm{Ca}\right)$ to +2 in Calcium oxide $\left(\mathrm{CaO}\right)$. Therefore, it is oxidized and is the reducing agent.

The oxidation state of Vanadium decreases from +5 in Vanadium pentoxide $\left({\mathrm{V}}_2{\mathrm{O}}_5\right)$ to 0 in Vanadium $\left(\mathrm{V}\right)$. Therefore, it is getting reduced and is the oxidizing agent.

Therefore, Calcium is the reducing agent and Vanadium pentoxide is the oxidizing agent.