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How does the combustion of coal to generate  electricity contribute to acid...

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islnds | (Level 1) Valedictorian

Posted August 8, 2012 at 6:32 PM via web

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How does the combustion of coal to generate  electricity contribute to acid precipitation?  Describe the chemical reaction involved as well.

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bandmanjoe | Middle School Teacher | (Level 1) Senior Educator

Posted August 11, 2012 at 5:27 PM (Answer #1)

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When fossil fuels like coal are combusted, or burned, to help generate electricity, one of the exhaust products produced is sulfur dioxide (SO2).  If left unchecked, the sulfur dioxide exits the energy plant through the smoke stack into the surrounding air.  The sulfur dioxide will readily combine with the water vapor already present in the air to produce a form of acid rain.  The chemical formula for acid rain is H2SO4, which is also the formula for sulfuric acid.  Acid rain is rain that has an over-abundance of hydrogen ions present in the molecular formula.  Those ions will combine with substances when the rain precipitates out of the atmosphere.  Acid rain is detrimental to fish and wildlife, as well as to cities infrastructure, peeling paint and eroding monuments and buildings.  The formula for the production of acid rain from the combustion of coal looks like this:

H2O + SO2 ---> H2SO4

The pH of acid rain is lower than the pH of normal rain, which is around 7, the midway point of the pH scale.  Acid rain typically has a pH of 4 to 5.

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