Chemistry C1

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  • C1- Atmosphere/ Air Quality
    • The atmosphere now!
      • 78% Nitrogen, 21% oxygen, 1% Argon and others
      • Human activity and volcano eruptions added other gases and particulates- most are pollutants.
    • Early atmosphere
      • Mainly carbon dioxide and water vapour.
      • Earth cooled and water vapour condensed into oceans
      • Carbondioxide dissolved into the oceans, later this made sedimentary rock and some fossil fuels.
      • Oxygen increased probably from early plants photosynthesis- taking in carbon dioxide and releasing oxygen
    • Air Pollutants
      • Coal is mainly carbon. Petrol, diesel and fuel oil is mainly hydrocarbons
      • Fossil fuels burn in vehicles and power stations- to generate electricity
      • Burning fossil fuels is a combustion reaction and a oxidation reaction as it adds oxygen to the chemicals.
      • Mass is conserved in a reaction but molecules are rearranged.
    • Types of Pollutants
      • Carbon dioxide- CO2
      • Carbon monoxide- CO, made when incomplete combustion occurs and also produces particulate carbon
      • Sulfur Dioxide- SO2, from some fossil fuels which contain sulfur and reacts with oxygen
      • Water- H2O
      • Nitrogen Monoxide- NO, in car engines air reacts with nitrogen- this is formed first
      • Nitrogen Dioxide- NO2, formed when nitrogen monoxide reacts with more oxygen
        • Nitrogen Oxides
          • Nitrogen Monoxide- NO, in car engines air reacts with nitrogen- this is formed first
    • Problems of Pollutants
      • Atmospheric Pollutants do not disappear
      • Carbon dioxide is used for photosynthesis and dissolves in rain and seas
      • Carbon Monoxide directly harms humans- reduces amount of oxygen blood can carry
      • Some directly harm the environment and indirectly harms humans
      • Sulfur dioxide and oxides of nitrogen react with water and oxygen to make acid rain
      • Carbon dioxide contributes to climate change
      • Particulate carbon makes surfaces dirty
    • Improving Air Quality
      • Power stations: use less electricity, remove sulfur impurities from natural gas and oil, remove sulfur dioxide and particulates from flue gases.
      • Vehicles: develop efficient engines, use low sulfur fuels, use catalytic converters( add oxygen or remove oxygen from nitrogen monoxide), use public transport, legal limits on exhaust emissions (MOT), use biofuels or electric cars.
      • Untitled
        • Wet scrubbing- removes sulfur dioxide from flue gases by reacting it with an alkali. Two alkalis used are: seawater and slurry of calcium oxide powder and water- makes calcium sulfate used in building plaster.
      • Biofuels: made from plants e.g. sugar canes, take carbon dioxide in from atmosphere then burn to release thems.
      • Electric Vehicles: do not produce waste gases during use but need fossil fuels for generating electricity usually, need recharging often

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