C1 - Air Quality

Atmospheric Evolution
1. Phase 1
  1. Volcanoes gave out gases
  2. Earth's surface was originally molten for many millions of years. Atmosphere 'boiled into space'. Earth cooled slightly, crust formed, volcanoes erupted.
    1. Volcanoes emit gas
      1. Atmosphere formed
        Carbon Dioxide, Water Vapour and Nitrogen
        Little Oxygen
        Water Vapour condensed
        Hydrosphere formation
2. Phase 2
  1. Evolution of green plants
  2. Green plants evolved over most of Earth. CO2 was removed from atmosphere by dissolving in the oceans and through photosynthesis. The levels of Oxygen began to increase.
    1. When plants died they were burried under layers of sediment. the Carbon that they had removed from the air (in CO2) become 'locked' in sedimentary rocks.
      1. Insoluble carbonates
      2. Fossil fuels
3. Phase 3
  1. Evolution of complex organisms
  2. The build up of Oxygen in the atmosphere killed off organisms that could not tolerate it but allowed other organisms to evolve (like humans).
    1. There is virtually no CO2 left now.
4. The atmosphere today
  1. Compsition
    1. Nitrogen
      1. 78%
    2. Oxygen
      1. 21%
    3. Argon
      1. 1%
    4. Carbon Dioxide
      1. <0.1%
    5. Water Vapour
      1. 0-4%
  2. Changing
    1. Human activity is changing our atmosphere
      1. Constant
        Nitrogem, Oxygen and Argon
      2. Increasing
        Pollutants
        Sources
        Burning fossil fules
        Nature
Molecules
1. Diagrams of air molecules
  1. Atoms
2. Reactions
  1. Rearranging of atoms
  2. No atoms are lost
    1. Sides must balance
  3. Reactants and products have very different properties
3. Fossil fuels
  1. Hydrocarbons
    1. Formed from the remains of dead plants and animals over millions of years
  2. Drilled from the Earth's crust and then refined to make products like petrol and diesel
    1. Fuels are a mixture of hydrocarbons
    2. Difference in fuels is the length of hydrocarbon
  3. Burning
    1. Combustion and oxidation
      1. Produced carbon dioxide and water
      2. Complete
        When a fuel is burned in plenty of Oxygen the fuel burns more rapidly and therefore a higher temperature can be reached
        Useful for welding
      3. Incomplete
        Occurs when not enough oxygen is supplied for complete combustion to occur
        Creates polution
Air Pollution
1. Carbon
  1. Combustion
    1. Complete
      1. Carbon Dioxide
    2. Incomplete
      1. Particulates
      2. Carbon Monoxide
  2. Polutants
    1. Carbon Dioxide
      1. Stays in atmosphere causing problems until removed
        Natural
        Photosynthesis
        Dissolving
      2. Greenhouse gas
        Warms Earth through 'Greenhouse Effect'
    2. Carbon Monoxide
      1. Poisonous
        Drowsy
        Headaches
        Suffocation - Death
    3. Particulate Carbon
      1. Tiny particles
        Float around
      2. Deposit themselves - soot
        Dirty looking
2. Sulphur
  1. Comes from impurities in fuels
    1. Impurities are present due to extraction of the fuels
  2. Sulphur Dioxide
    1. Can only leave atmosphere in the from of acid rain
    2. Acid rain
      1. When SO2 reacts with H2O it becomes H2SO4
        Dilute Sulphuric Acid
      2. Problems
        Acidifies lakes
        Kills plants and animals
        Rain
        Damages buildings and statues made from weak stone
        Limestone
        Kills trees
3. Nitrogen
  1. Involves Nitrogen from the air
    1. When fuels are burnt at extreme temperatures atoms in the air react
      1. Nitrogen oxidises to create Nitrogen Oxides
        NO
        NO2
  2. Polutants
    1. NO
      1. Formed in car engines; N and O react
    2. NO2
      1. Formed when NO reacts in air with more O
    3. Problems
      1. Similar to sulphur dioxide
        NOx react with moisture in the air to form dilute nitric acid
        Acid Rain
Reducing Pollution
1. Power Stations
  1. Use less electricity
    1. Decreases fossil fuel consumption
  2. Remove sulphur impurities from fossil fuels before industrial combustion
  3. SO2 and particulattes can be removed from industrail chimneys
    1. SO2 can be removed by reacting it with an alkali
      1. aka. 'wet scrubbing'
        Sea Water: SO2 reacted with sea water produces CO2, H2O and dissolved SO4
        Alkine Slurry - CaO(aq): Slurry is sprayed onto gasses and SO2 reacts with the CaO. CaS (s) formed.
2. From Cars
  1. More efficient engines
    1. Burn less fuel - create less polution
  2. Catalytic converters
    1. Convert NO into harmless N and O
    2. Convert CO into CO2 by adding O2
  3. Legal limit on amount of pollution from cars
3. New technology
  1. New cars
    1. Biofuels replacing petrol
      1. Renewable energy source
        Plants and waste
        Only produce CO2 and H2O
        Carbon neutral
      2. One problem
        Deforrestaion to create room for bio-fuel farms
    2. Electric Baterries
      1. No exhaust gases
      2. However...
        Electricity is still needed and therefore fossil fuels are still burnt

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C1 - Air Quality

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	Created by nicole_j_baldwin almost 11 years ago