C1 - AIR QUALITY

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  • C1 - Air Quality
    • Evolution of atmosphere
      • Phase 1 - volcanoes gave out gases
        • Earth's surface was originally molten = hot & atmosphere boiled away
        • Cooled = thin crust, volcanoes still erupt
        • Volcano gas = CO2, water vapour & nitrogen - atmosphere had no oxygen
      • Phase 2 - Green plants evolved & produced oxygen
        • Green plants liked CO2 atmosphere
        • CO2 dissolved into ocean, plants also removed CO2 & produce O2 = photosynthesis
        • Carbon from dead plants became locked up in sedimentary rocks as fossil fuels
      • Phase 3 - Complex organisms evolved
        • Build up of O2 killed off some organisms that couldn't tolerate it but allowed others to evolve
    • The atmosphere today
      • The atmosphere contains various chemicals
        • Nitrogen = 78% Oxygen = 21% Argon = 1%
      • Human activity is changing the atmosphere
        • Human activity adds pollutants to the air = CO2, sulphur dioxide and nitrogen oxides
        • Some are released by nature
        • Some are directly harmful = diseases       Some are indirectly harmful = harm environment
    • Chemical reactions
      • Substances = tiny particles of atoms
      • Joined atoms = molecules
      • Chemical reactions happen when atoms are rearranged
        • Chemical reaction = rearrange atoms
        • Reactants become products and no atoms are lost
      • Reactants and products often have different properties
        • Atoms rearrange but products formed have their own properties - these can be very different from reactant properties
    • Fossil fuels
      • Fossil fuels are hydrocarbons
        • Most fuels contain carbon and hydrogen = hydrocarbons
      • Burning fossil fuels is an example of oxidation
        • Burning (combustion) is a chemical reaction
        • Hydrocarbons burn, hydrogen atoms combine with oxygen = hydrogen oxide
        • Carbon atoms combine with oxygen atoms = carbon dioxide
        • Reaction adding oxygen = oxidation
        • Oxygen lost = reduction
    • Air pollution - carbon
      • Different forms of carbon pollution cause problems
        • Fossil fuels contain carbon, it burns with lots of oxygen = carbon dioxide
        • Burnt with little oxygen = carbon monoxide and carbon particles
      • Carbon dioxide
        • Stay in atmosphere until removed
        • Can be removed naturally through photosynthesis
      • Carbon monoxide
        • It is poisenous - make you ill
    • Air pollution - Sulphur
      • Comes from impurities in fuels
        • Some sulphur burns and combines with oxygen to make sulphur dioxide
      • It produces acid rain
        • Acid rain causes lakes to become acidic, killing plants & animals, it also kills trees

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