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air and the atmosphere - Coggle Diagram
air and the atmosphere
air is a mixture of different gases and contains different elements and compounds that are needed by living things. its composition varies from time to time and from place to place
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air pollution
it is the condition in which air contains a high concentration of chemicals that are harmful to living things and can damage them
air pollutants are unwanted chemical substances in the air that can cause harmful effects to the environment and living things (note that CO2 is not a harmful pollutant)
- carbon monoxide
it is colourless and odourless and comes from the incomplete combustion of petrol in car engines
- sulfur dioxide
it is produced in large quantities during volcanic eruptions and when fossil fuels such as coal, crude oil (petroleum) and natural gas (that contain sulfur) are burnt in motor vehicles, power stations and factories
- oxides of nitrogen
they are produced in car engines, chemical factories or when lightning strikes as nitrogen combines with the oxygen in the air to form nitrogen monoxide or nitric oxie (NO)
- nitrogen monoxide reacts with oxygen to form nitrogen dioxide which is a brown gas (NO2)
- during thunderstorms, the heat energy released by lightning causes nitrogen and oxygen in the air to react to form oxides like nitrogen monoxide and nitrogen dioxide
- unburnt hydrocarbons, methane and ozone
unburnt hydrocarbons are released in car exhaust fumes and chemical plants
methane is a colourless and odourless gas produced when plant and animal matter and rubbish in landfills decay/decompose. sheep and cattle also give off methane due to digeston of food.
ozone (photochemical smog) is formed when nitrogen dioxide in the air reacts with unburnt hydrocarbons in the presence of sunlight
effects of air pollution
carbon monoxide
- reacts with haemoglobin in the blood to form a stable compound known as carbonoxyhaemoglobin, which reduces the ability of haemoglobin to transport oxygen to the rest of the body, resulting in headaches, fatigue, breathing difficulties, brain damage and death
sulfur dioxide
- irritates the eyes and lungs, causing breathing difficulties
- high levels of it leads to inflammation of the lungs, known as bronchitis
- it reacts with water in the atmosphere to form acid rain which corrodes buildings and harms aquatic life and plants
unburnt hydrocarbons
- is carcinogenic and can cause cancer
- reacts with nitrogen oxides to form ozone
methane
- is a greenhouse gas and causes gobal warming
ozone
- forms photochemical smog and irritates the eyes and lungs, causing breathing difficulties and damaged crops
acid rain
it is formed when acidic air pollutants like sulfur dioxide and nitrogen oxides react with water in the atmosphere and has a pH value of 4 or less
- sulfur dioxide dissolves in water to form sulfurous acid (weak acid) and in the presence of oxygen in the air, sulfurous acid then slowly oxidises to form sulfuric acid (strong acid)
SO2(g) + H2O(l) --> H2SO3(aq)
2H2SO3(aq) + O2(g) --> 2H2SO4(aq)
- nitrogen oxides react with oxygen and water to form nitric acid
4NO2(g) + 2H2O(l) + O2(g) --> 4HNO3(aq)
- carbon dioxide in the air dissolves in rainwater to form carbonic acid (weak acid), resulting in the pH value of unpoluted water being slightly below 7
CO2(g) + H2O(l) --> H2CO3(aq)
effects of acid rain on buildings, plants and aquatic life
- the pH value of natural water bodies like lakes and streams are reduced from between 6.5 and 8.5 to 4, making it too acidic for fish and other aquatic life to survive
- metal bridges and stone buildings are destroyed as the acid rain will react with metals and carbonated like marble and limestone
- nutrients from the soil are leached, causing plants to wither and die
- aluminium ions (Al3+), which are toxic to plants, are produced as acid rain reacts with aluminium hydroxide
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