Question

How is SO₂ an air pollutant?

Answer 1

Sulphur dioxide causes harm to the environment in many ways:

1. It combines with water vapour present in the atmosphere to form sulphuric acid. This causes acid rain. Acid rain damages soil, plants, and buildings, especially those made of marble.
2. Even in very low concentrations, SO₂ causes irritation in the respiratory tract. It causes throat and eye irritation and can also affect the larynx to cause breathlessness.
3. It is extremely harmful to plants. Plants exposed to sulphur dioxide for a long time lose colour from their leaves. This condition is known as chlorosis. This happens because the formation of chlorophyll is affected by the presence of sulphur dioxide.

Answer 2

Sulphur dioxide gas is extremely dangerous. Its presence in the air can cause eye discomfort, throat issues, heart problems, respiratory disorders, and more. It is instrumental in creating acid rain, which has various adverse impacts on plants and animals. Additionally, it corrodes buildings, marble structures, textiles, paper, leather, and other materials. The photochemical reactions that result in acid rain are listed below.

\[\ce{SO2 + hv -> SO^*_2}\]

\[\ce{SO^*_2 + O2 -> SO3 + O}\]

\[\ce{SO^*_2 + SO2 -> SO3 + SO}\] 

\[\ce{SO + SO2 -> SO3 + S}\]

\[\ce{SO3 + H2O ->\underset{acid rain)}{\underset{(present in}{H2SO4}}}\]