Question

How does the flow of acid rain water into a river make the survival of aquatic life in the river difficult?

Answer 1

1. Acid rain refers to a form of precipitation with acidic components such as sulfuric acid(${\mathrm{H}}_2{\mathrm{SO}}_4$) or nitric acid(${\mathrm{HNO}}_3$).
2. Chemical equations of formation of acid rain:

$$\begin{gathered} {\mathrm{SO}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{SO}}_3\left(\mathrm{g}\right) \\ (\mathrm{Sulphur}\mathrm{dioxide})\left(\mathrm{Oxygen}\right)(\mathrm{Sulphur}\mathrm{trioxide}) \\ {\mathrm{SO}}_3\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right) \\ (\mathrm{Sulphur}\mathrm{trioxide})\left(\mathrm{Water}\right)(\mathrm{Sulphuric}\mathrm{acid}) \end{gathered}$$

and $$\begin{gathered} 3{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2{\mathrm{HNO}}_3\left(\mathrm{aq}\right)+\mathrm{NO}\left(\mathrm{g}\right) \\ (\mathrm{Nitrogen}\mathrm{dioxide})\left(\mathrm{Water}\right)(\mathrm{Nitric}\mathrm{acid})(\mathrm{Nitrogen}\mathrm{monoxide}) \end{gathered}$$

3. The flow of acid rain into a river brings in additional substances like sulfuric acid or nitric acid which lowers the pH of the river water.

4. As mostly aquatic animals can survive in water within a pH of 7-8, they start dying in acidic water as their body organs stop functioning.

5. Hence, the flow of acid rainwater into a river makes the survival of aquatic life in the river difficult by decreasing its pH.