Acid rain results from the combustion of fossil fuels which releases sulfur and nitrogen oxides that react with water to form sulfuric and nitric acids, leading to a pH of less than 5.6. Major affected areas include parts of Europe and India, where pH levels have been recorded as low as 2.2, causing significant environmental damage. To mitigate acid rain, cleaner fuels, flue gas desulfurization, and liming practices are recommended.

1. Acid Rain
DEVELOPED BY MEGH SHAH
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2. What does the term mean?
• From burning of fossil fuels, a large amount of carbon-di-oxide gets emitted.
This gas further reacts with the water. The formula is CO2+ H2O -> H2CO3.
• The pH of natural rain water is 5.84 at temperature of 25o C. However, if the
rain water has pH less than 5.6 it is said to be acid rain.
• The adverse impacts of acid rain can be experienced only if pH is about 4.5 or
less.
• The term acid raid was first used by Robert Angus in 1872 which means
presence of acids in rain water.
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3. Components & Forms of Acid Rain
• Sulfuric acid and nitric acid are major acids found in rain water along
with small quantity of hydrochloric acid.
• The proportion of sulfuric acid may be ranging 60 to 70 percent
whereas nitric acid has proportion of about 30-40 percent.
• Acid rain is also termed as acid deposition and may be either wet or
dry. The wet form includes rain, snow, mist, etc. whereas dust particles
containing sulfates and nitrates setting on surface are included in dry
form.
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4. Reason Behind Acid Rain
• The fossil fuels contain sulphur and nitrogen. Burning of sulphur and
nitrogen results in formation of sulfuric oxides and nitric oxides.
• These oxides are soluble and ultimately make the acid rain.
1. S + O2 = SO2
2. NO + O3 = NO2 + O2
• It is not necessary that the acid rain takes place where the oxides of
sulphur and nitrogen are produced.
• Sometimes the acid droplets are carried away by wind storm and acid
rain takes place.
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5. Effects of Acid Rain
• Europe, Netherlands, Sweden, USA and so many countries faced
problem of acid rain with pH 5.0 to 2.2.
• In India, the cities of Kanpur and Bombay have experienced the
adversity of acid rain.
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6. Precautions to stop Acid Rain
Use Cleaner Fuels
• Natural Gas
• Coal that produces
less smoke.
• Wash the coal to
reduce sulphur
content.
Flue Gas
Desulphurization
• Removes sulphur
dioxide form waste gas
• Every factory should
use to reduce
Pollution.
• Government should
make it mandatory.
Reduce effects of
acid rain by liming
• Powdered limestone
added to water or soil
to neutralize acids.
• Sweden and Norway
use it extensively.
• Expensive & short
term remedy.
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