Question

Nitric acid (${\mathrm{HNO}}_3$) acts only as an oxidizing agent while nitrous acid (${\mathrm{HNO}}_2$) acts both as an oxidizing as well as reducing agent. Explain.

Answer 1

Oxidation and Reduction:-

1. Oxidation is actually a chemical process in which there is the loss of the electrons or the increase in the oxidate state of the chemical atoms, and the substance which will tend to bring the oxidation in other by being reduced and gaining electrons are termed as Oxidizing agent.
2. Reduction is basically the gain of the electrons or there would be the decrease in the oxidation state of the chemical atoms, and the substance which will lead or tend to bring the reduction in other by being oxidized or losing the electrons are termed as Reducing agent.
3. So, the oxidation number of Nitrogen in ${\mathrm{HNO}}_3$ = +5 which is it's maximum and minimum be = -3.
4. Because of the maximum oxidate state in ${\mathrm{HNO}}_3$, it has the only option to drop by gaining the electrons which will act as Oxidizing agent.
5. The oxidation state of the $\mathrm{N}$ in ${\mathrm{HNO}}_2$ = +3 , so it can be either reduced or oxidized for getting stable.
6. So, as a result ${\mathrm{HNO}}_2$ will act as both oxidizing as well as reducing agent.

Therefore, Nitric acid (${\mathrm{HNO}}_3$) will act only as an oxidizing agent while nitrous acid (${\mathrm{HNO}}_2$) will act both as an oxidizing as well as reducing agent.