Friday, December 11, 2009

What is Acid Rain?

Acid rain is rain or any other form of rainfall that is curiously acidic, i.e. high levels of hydrogen ions (low pH). It has damaging effects on plants, sea animals, and communications Acid rain is mostly caused by emissions of compounds of sulfur, nitrogen, and carbon which react with the water molecules in the ambiance to produce acids. However, it can also be caused naturally by the splitting of nitrogen compounds by the energy produced by lightning strikes, or the release of sulfur dioxide into the atmosphere by phenomena of volcano eruptions.


"Acid rain" is a popular term referring to the authentication of wet (rain, snow, sleet, fog and cloud water, dew) and dry (acidifying particles and gases) acidic components. A more accurate period is “acid deposition”.

Distilled water, which contains no carbon dioxide, has a impartial pH of 7. Liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are bases. “Clean” or uncontaminated rain has a slightly acidic pH of about 5.2, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid (pH 5.6 in distilled water), but uncontaminated rain also contains other chemicals.

H2O (l) + CO2 (g) → H2CO3 (aq)
Carbonic acid then can ionize in water forming low concentrations of hydronium and carbonate ions:

2 H2O (l) + H2CO3 (aq) CO32− (aq) + 2 H3O+ (aq)
Acid deposition as an environmental issue would include additional acids to H2CO3.

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