1. Rain water has a pli of 5.6 due to the dissolution of CO., into it. Oxides of sulphur and nitrogen in the atmosphere may be absorbed by droplets of water that make up the clouds and get chemically converted into sulphuric acid and nitric acid. Due to this the pH of rain water drops below the level of 5.6. Hence it is called acid rain.
2. Acid rain is a by-product of sulphur and Nitrogen oxides in the atmosphere. Burning of fossil fuels in power stations, furnaces and petrol, diesel in motor engines produce SO2 and NO2 gases. They are converted into H2SO4 and HNO3 by the reaction with oxygen and water.
3. 2SO2 + O3 + 2H2O → 2H2SO4
4NO2 + O2 + 2H2O → 4HNO3
Harmful effects of acid rain:
1. Acid rain causes damage to buildings made us of marbles. This attack on marble is termed as stone leprosy.
CaCO3 + H2SO2 CaSO4 + H2O + CO2 ↑
2. Acid rain affects plant and animal life in aquatic ecosystem.
3. It is harmful For agriculture, as it dissolves in the earth and removes the nutrients needed for the growth of plants.
4. It corrodes water pipes resulting in the leaching of heavy metals such as iron, lead and copper into drinking water which have toxic effects.
5. it causes respiratory ailment in humans and animals.
