Question

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

$2{\mathrm{H}}_2+{\mathrm{O}}_2\to 2{\mathrm{H}}_2\mathrm{O}$

Answer 1

1. Redox reactions

Redox reactions involve oxidation and reduction reactions. Oxidation involves the removal of electrons and the reducing agent of the reaction undergoes oxidation. Reduction involves the addition of electrons and the oxidizing agent of the reaction undergoes reduction.

The change in the oxidation state of the species can be used to find the oxidizing and reducing agent as oxidation causes an increase in the oxidation state and reduction causes a decrease in the oxidation state.

2. Identifying oxidizing and reducing agents

$$\begin{gathered} 2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Hydrogen}\mathrm{Oxygen}\mathrm{Water} \end{gathered}$$

Hydrogen $\left({\mathrm{H}}_2\right)$ is the reducing agent as its oxidation state changes from 0 in Hydrogen to +1 in Water $\left({\mathrm{H}}_2\mathrm{O}\right)$. It undergoes oxidation.

The oxidation state of Oxygen changes from 0 in Oxygen $\left({\mathrm{O}}_2\right)$ to -2 in Water. Therefore, Oxygen undergoes reduction and is the oxidizing agent.

Therefore, Hydrogen is the reducing agent and Oxygen is the oxidizing agent.