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Acid Rain

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by

Ashly J

on 27 July 2014

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Transcript of Acid Rain

Causes
A chemical reaction begins when compounds like sulphur dioxide and nitrogen oxides are released into the air.
these can rise very high into the atmosphere where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants (harmfull particles)
sulphur dioxides and nitrogen oxides dissolve very easily in water and can be carried very far by wind to be part of precipitation we experience
Effects on environment
The Chemistry
Carbon dioxide can dissolve in rain water to form carbonic acid, H2CO3.
CO2 + H2O --> H2CO3
Carbonic acid is weak and partially ionises to form hydrogen ions.
H2CO3 --> H^+ + HCO3^-
The hydrogen ions from carbonic acid give natural rain water slightly acidic.

When coal is burned in electricity powered stations, sulfur impurities form sulfur dioxide.
S + O2 --> SO2
When fuels obtained from crude oil are burned, sulfur dioxide is released into the air and it reacts with water and oxygen to form sulfuric acid, H2SO4, a strong acid
H2SO4 2H^+ + SO42^-
Acid Rain
What is acid rain?
rain that has been made acidic by pollutants in the air
a type of acid deposition (acidic material that falls from the atmosphere to the earth) which can appear in wet (rain, sleet, snow or fog) and dry (gases and dust) forms
it can be carried by wind for very long distances
Human activities
many different chemicals are released into the air and they change the mix of gases in the atmosphere
power plants release sulphur dioxides and nitrogen oxides when they burn fossil fuels (coal, oil and gas) to produce electricity
also, the exhaust from cars and other automobiles releases nitrogen oxides and sulphur dioxide into the air
Forests
Acid rain that seeps into the ground can dissolve nutrients, such as magnesium and calcium, that trees need to be healthy
Causes aluminium to be released into the soil - difficult for trees to take up water.
Trees located in mountainous regions at higher elevations are at greater risk as they are exposed to acidic clouds and fog - more acid than rain or snow
Acidic clouds strup important nutrients from their leaves - makes it easier for infections, insects and cold weather to damage trees and forests
Lakes and streams
Without pollution or acid rain, most lakes and streams would have a pH level near 6.5
But acid rain has caused many lakes and streams to have much lower pH levels
Auminium released into the soil eventually ends up in lakes and streams
This increase can be deadly to aquatic wildlife
Naturally acidic?
normal precipitation reacts with alkaline chemicals, found in air and soils, which neutralize natural acids
but this isn't possible if it becomes too acidic (from the presence of pollutants in the air)
What is being done?
The best way to counteract acid rain is by reducing pollution.
Some ways we can reduce the amount of sulphur dioxide released from coal-burning power plants include:
Using coal containing less sulphur
Washing the coal to remove some sulphur
Power plants can install equipment called scrubbers which remove the sulphur oxide from gases leaving the smokestack

Another great solution is to find other sources of energy.

Renewable energy sources, such as solar and wind power, are already being used instead which produce much less pollution than fossil fuels.
Cleaner cars, less harmful to the environment should be used.

Car manufacturers are required to reduce the amount of nitrogen oxides and other pollutants released by new cars

Principles of Green Chemistry
Many principles of green chemistry apply to acid rain, but the main ones are to:
Design less hazardous chemical syntheses
: the amount of sulphur dioxide and nitrogen oxides emitted should be kept to a minimum by designing cleaner cars and removing sulphur from coal.
Use renewable raw materials
: instead of fossil fuels, renewable energy sources such as solar and wind power should be used.

Bibliography
BBC. 2010. GCSE Bitesize: The Acid Rain Problem. [ONLINE] Available at: http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/context_chemistry/acidrainrev1.shtml. [Accessed 25 July 14].
DIMY Barboza. (2013). What is acid rain? // Chemistry II. [Online Video]. 09 June. Available from: [Accessed: 25 July 2014].
EcoPol, (2013), Toxic Building Materials: Acid Rain [ONLINE]. Available at: http://2.bp.blogspot.com/-G4LykaF0nd4/UUwDdG4JJrI/AAAAAAAADAs/p6c2QJ7rONY/s1600/envi_index_global+warming_acidrain_clip_image003.gif [Accessed 25 July 14].
Encyclopaedia Britannica. (2009). Coal Combustion and Acid Rain. [Online Video]. 22 May. Available from: [Accessed: 25 July 2014].
EPA. 2014. Acid Rain Students Site: What is acid rain?. [ONLINE] Available at: http://www.epa.gov/acidrain/education/site_students/whatisacid.html. [Accessed 25 July 14].
Lukins, N et al., 2011. Heinemann Chemistry 1 Enhanced. 4th ed. Port Melbourne: Pearson Australia.
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