OCR 21st Century Science, Chemistry - C1

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The Atmosphere

  • The earth is surrounded by a thin layer of gases called the atmosphere which contain:
    • 78% - Nitrogen (N2)
    • 21% - oxygen (O2)
    • 1% - Argon (Ar) and other noble gases
    • 0.04% - Carbon Dioxide (CO2)
    • 0-4% - Water vapour (varies according to weather conditions)
  • The earth's atmosphere id just 1km thick while the diameter is over 12 000km.
  • the earth is heated by the sun but at the same time the earth also radiates heat back out as infrared energy. the earth's greenhouse gases (methane [CH4], Carbon dioxide [CO2], Water Vapour [H2O]) absorb the heat to stop it from escaping into space. So the earth is warmer then it would be.
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Pollutants

  • Sulphur Dioxide (SO2) - causes acidic rain which kills plants and water creatures.
  • Carbon Monoxide (CO) - A poisonous gas which reacts with blood.
  • Nitrogen Dioxide (NO2) - causes acidic rain, causes breathing problems, makes asthma conditions worse.
  • Particulates - make things dirty, make lung infections worse, makes asthma worse.
  • Units used for measurement are PPB(parts per billiion) or PPM (parts per million).
  • Measurements can vary because:
    • Varibles - factors that change
    • Measuring equipment has a limited digree of accuracy
    • the user's skill of accuracy
  • Chemicals - atom -> element -> Molecules.
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Carbon Dioxide

  • For a complete combustion all the reactants must be present with the right amount needed to make the products.
  • Incomplete combustion happens when there is a shortage of an element that is needed to make the product.

Photosynthesis Formulae

Water(H2O) + Carbon Dioxide(CO2) -----> Oxygen(O2) + Glucose(C6H12O6)

  • Carbon dioxide enters the atmosphere by:
    • Burning fossil fuels
    • Humans breathing out
    • Respiration
    • Land use
  • Carbon dioxide is removed from the atmosphere by:
    • Photosynthesis
    • Dissolves in ain water and sea water
    • Some is stored in Limestone
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Improving Air Quality

  • Emissions from power stations can be reduced by:
    • Using less energy so less fuel is burned
    • Using a filter system to remove Sulphur dioxide and particulates from flue gases before they leave a coal burning power station.
    • Removing toxic chemicals before they are burned.
    • Using alternative renewable energy sources like solar, wind, hydroelectric energy instead of fuels.
  • Emissions from motor vehicles can be reduced by:
    • Buying a car with a modern engine that burns less fuel.
    • Buying a hybrid car which uses electric power in the city centre and can change to petrol for longer journeys,
    • Using a low sulphur fuel to reduce the amount of sulphur dioxide released.
    • Converting the engine to run on biodiesel, a renewable fuel.
    • Using public transport so there are less vehicles on the road.
  • A catalytic converter chances a harmful chemical and changes it into a less harmful chemical without itself being effected.
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Comments

...

thanks a lot that helped a lot! i love the fact you minimized the info so it was just facts! thanks :)

Maddi


Really helped me!

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