Question

How is acid rain formed?

Answer 1

1. Rainwater 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 rainwater 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. \[\ce{2SO2 + O3 + 2H2O → 2H2SO4}\]
   \[\ce{4NO2 + O2+ 2H2O → 4HNO3}\]