The Chemistry Of Acid Rain.

The following section will try to explain some of the chemical processes taking place when "Acid Rain" causing chemicals get into the atmosphere.

  • Rainwater is slightly acidic.

    • CO2+H2O-->H2CO3

    H2CO3-->H++HCO3

    Carbon Dioxide can dissolve in water, some of which forms Carbonic Acid. Carbonic Acid releases H+ making the water slightly acidic.

  • Burning Sulphur releases SO2.

    • 2S+O2-->2SO2

    Sulphur in coal released as Sulphur Dioxide.

  • Sulphur Dioxide acidifies water slightly.

    • SO2+H2O-->H2SO3

    H2SO3-->H++HSO3

    Sulphur Dioxide can dissolve in water, some of which forms Sulphurous Acid, which releases H+ making the water slightly acidic.

  • Oxidation of Sulphur Dioxide results in a stronger acid

    • SO2+O2-->SO3

    Oxidation produces Sulphur Trioxide.

    SO3+H2-->H2SO4

    Sulphur Trioxide dissolves in water, forming Sulphuric Acid.

    H2SO4-->H++HSO4-

    Sulphuric Acid dissociates into H+ and the Hydrogen Sulphate ion, making acidic water.

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    • Author: John Bowler (document modification date: 22nd May 2003)