E2+Acid+Rain

__**E2 Acid Depositions**__
__E2.1__ __What are acid depositions?__ Acid deposition is the natural process in which precipitation, particles falls from the atmosphere. There are two different types of acid depositions:
 * Wet depositions, which include snow, fog and acid rain
 * Dry depositions, including acidic particles and gases such as sulfur dioxide which is usually deposited as a gas then a salt.

__What is acid rain?__ Rain water is typically acidic (pH 5.6) due to the carbon dioxide gas (CO2) in the atmosphere whereas acid rain has an elevated levels of hydrogen ions, leading to lower pH levels.

__What causes acid rain?__ Atmospheric pollutants such as sulfur dioxide and nitrogen oxides mix with water vapour in the air, which then gets converted into sulfuric and nitric acids and they make rain acidic.




 * Burning of sulfur**:-
 * Sulfur naturally exists in volcanoes and when these are burnt sulfur dioxide is produce.

S(s) + O2(g) --> SO2(g)
 * Further oxidation can take place when sulfur dioxide is exposed to oxygen and the sunlight, which will produce sulfur trioxide. 2SO2(g) + O2(g) --> 2SO3(g)

SO3(g) + H2O(l) --> H2SO4(aq)
 * Sulfur trioxide will dissolve in rain water in the atmosphere to form sulfuric acid in the follow equation.

N2(g) + O2(g) --> 2NO(g)
 * Burning of nitrogen:-**
 * Nitrogen oxide occurs mainly in the burning of petrol but they are also produced during thunder storms.
 * Further oxidation occurs to form nitrogen dioxide in the presence of sunlight and oxygen in the atmosphere. 2NO(g) + O2(g) --> 2NO2(g)


 * This will form nitric acid when nitrogen dioxide dissolves in rain water with more oxygen from the atmosphere in the following equation. 4NO2(g) + O2(g) + H2O(l) --> 4HNO3(aq)


 * Formation of acid rain:-**
 * Lastly, the rain water which is now acidic with the nitric acid and sulfuric acid will fall down on earth as acid rain.

__E2.2__ __Environmental effects of acid deposition__
 * Erosion will occur to rocks that contain calcium carbonate, for example limestone and marble. This is because calcium carbonate will react with the acids in the rain.
 * The acid rain will affect plants as the soil will be more acidic which is not suitable for plant life to grow in, they may not grow properly.
 * Fish and other aquatic life will be affected by the change in acidity of the water because they are unable to live in water below a certain pH.
 * Drinking water will also be affected, which will therefore affect the health of humans. This can lead to diseases such as Alzheimer's, lung problems and throat problems.

Effects of acid rain on trees:-



__Methods to counteract the effects of acid deposition__
 * Reducing the amount of nitrogen dioxide produced from cars by using catalytic converters or encourage the use of public transport to reduce the emission of pollutant gases.
 * Rather than coal and petrol, use alternative forms of energy such as solar power.
 * Reducing the amount of sulfur dioxide produced from the combustion of coal by using fluidized beds.
 * Adding calcium oxide base (lime) to soil or water to neutralize the acid.

Youtube video - The Causes and Effects of Acidic Precipitation:

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