Question

Nitric oxide can catalyse ozone formation in troposphere. Justify.

Answer 1

1. Nitric oxide $\text{(NO})$ in the troposphere reacts with the oxygen forming nitrogen dioxide.
2. The chemical reaction involved is: $$\begin{gathered} 2\mathrm{NO}\left(\text{g}\right)+{\mathrm{O}}_2\left(\text{g}\right)\to 2{\mathrm{NO}}_2(\text{g)} \\ \mathrm{Nitrogen}\mathrm{Oxygen}\mathrm{Nitrogen} \\ \mathrm{oxide}\mathrm{dioxide} \end{gathered}$$
3. Nitrogen dioxide, in the presence of light, decomposes to $\text{NO}$ and nascent oxygen $\left(\right[O\left]\right).$

$$\begin{gathered} {\mathrm{NO}}_2\left(g\right)\stackrel{\text{light}}{⟶}\mathrm{NO}\left(g\right)+\left[\mathrm{O}\right] \\ \mathrm{Nitrogen}\mathrm{Nitrogen}\mathrm{Nascent}\mathrm{oxygen} \\ \mathrm{dioxide}\mathrm{oxide} \end{gathered}$$

4. The nascent oxygen produced is highly reactive and oxidises oxygen to ozone.
$$\begin{gathered} {\text{O}}_2\left(\text{g}\right)+\left[\text{O}\right]\to {\text{O}}_3\left(\text{g}\right) \\ \mathrm{Oxygen}\mathrm{Nascent}\mathrm{Ozone} \\ \mathrm{oxygen} \end{gathered}$$