Gases in the air

The Earths Atmosphere

the Earths atmosphere was probably formed about 4 billion years ago by gases given out by volcanoes
Volcanoes release huge amounts of carbon dioxide and water vapour, they also release lava and dust
the Earths early atmosphere was mainly carbon dioxide

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humans are changing gases in the atmosphere by burning fuels
fuels are used in factories, power stations, for transport, and in homes
pollutant gases include carbon monoxide, nitrogen oxides, and sulfur dioxide
carbon dioxide is linked to climate change by acting as a greenhouse gas trapping heat in the atmosphere
when air pollution levels are high, more deaths from athsma heart disease and lung disease occur, there is a correlation between air quality and health
sulfur dioxide and nitrogen dioxide are pollutants that make acid rain

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small amounts of carbon dioxide in the air are measured in parts per million, 1 ppm means there is 1 gram of the pollutant per 1 million grams of air
other pollutant gases are measured in parts per billion

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Oxygen is needed for any fuel to burn and release energy
fossil fuels such as petrol, diesel and fuel oil are mainly hydrocarbons
hydrocarbons only contain hydrogen and carbon atoms
when a hydrocarbon fuel burns; HYDROCARBON FUEL+OXYGEN--->CARBON DIOXIDE+WATER(+ENERGY)
oxidation is when oxygen is added to a substance
reduction is when oxygen is removed from a substance
combustion is an oxidation reaction

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atoms do not change, in chemical reactions atoms get rearranged to make new substances
atoms of non-material elements join to form molecules
elements are rearranged to make new compounds in chemical reactions
atoms in reactants are rearranged into new products with different properties

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sulfur is insoluble but sulfur dioxide dissolves in water to make an acid solution
when fossil fuels burn sulfur burns, because fossil fuels contain small amounts of sulfur from the plants and animals that formed them
coal often contains sulfur
acid rain lowers the pH when it falls on land or enclosed water, harming living things or eroding carbonate rock
acid rain does not affect humans directly, so it is an indirect pollutant

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power stations and transport make most pollution because they burn most fuel
electricity production and transport has increased over the last century
if not enough air is available to burn the fuel, poisonous carbon monoxide is made and carbon particulates are made
car engines make nitrogen oxides when nitrogen and oxygen from the air react at high temperatures, this contributes to acid rain
carbon monoxide are formed during incomplete combustion
nitrogen monoxide is formed in furnaces and engines at a temperature at about 1000 degrees

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pollutants are removed from the air when particulate carbon settles on surfaces, carbon dioxide is used by plants for photosynthesis, carbon dioxide dissolves in rain water
reducing electricity reduces fossil fuel use in power stations
wet scrubbing methods used to remove sulfur dioxide from power station waste gases: using an alkaline solution of calcium oxide and water which can be sold as plaster, and using sea water which absorbs sulfur dioxide

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an alternative to fossil fuels is biofuels, which are made from plants
biofuels are carbon neutral, so when they burn they release the same amount of carbon dioxide that the plant origionally took to grow
large areas of land are needed to grow biofuels
fossil fuels are not renewable, so are not sustainable

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air pollution from vehicles can be reduced by using cars less, using cleaner fuels, and using more public transport
catalytic converters contain a platinum catalyst that allows gases to react with eachother, CARBON MONOXIDE+NITROGEN MONOXIDE--->NITROGEN+CARBON DIOXIDE
carbon monoxide gains oxygen so it is oxidised
nitrogen monoxide loses oxygen so it is reduced
legal limits for exhaust emissions are enforced by strict MOT tests

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