C3

  • Geologists study rocks to see how the Earths surface has changed
  • geological changes happen by slow movements of tectonic plates
  • plate collisions build mountain ranges which erode over time
  • geologists can explain most of the past history of the Earth by processes they can observe today
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Britain

  • over millions of years Britain has moved across the Earths surface
  • 600 million years ago, England and Wales were seperated by Scotland
  • different continents drifted and crashed together to form a supercontinent, Pangea
  • Britain was nearer the equator with a warmer climate
  • Different climates existed in Britian from tropical swamps to ice ages 
  • as volcanic lava solidifies, igenous rocks are formed
  • magnetic materials in the lava line up along the Earths magnetic field
  • Geologists can date rocks and track the slow movement of continents using changes in magnetic patterns, linked to radioactive decay
  • the evidence supports plate tectonic theory
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Britain

  • over millions of years Britain has moved across the Earths surface
  • 600 million years ago, England and Wales were seperated by Scotland
  • different continents drifted and crashed together to form a supercontinent, Pangea
  • Britain was nearer the equator with a warmer climate
  • Different climates existed in Britian from tropical swamps to ice ages 
  • as volcanic lava solidifies, igenous rocks are formed
  • magnetic materials in the lava line up along the Earths magnetic field
  • Geologists can date rocks and track the slow movement of continents using changes in magnetic patterns, linked to radioactive decay
  • the evidence supports plate tectonic theory
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Rocks

  • Coal contains fossils of the plants that formed it
  • Limestone contains bits of shell fragments from sea creatures
  • Rock salt contains different shaped water eroded grains and wind eroded grains
  • Ripple marks in rocks indicate water flow from rivers or waves in the sea
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Salt

  • used in the food industry, and to treat icy roads in winter
  • salt can be obtained from collecting and evaporating sea water, mining, and underground deposits of rock salt
  • rock salt is spread on icy roads because rock is insoluble but the sand in the rock gives it grip
  • salt extraction from sea water is only economical in hot climates

risks of eating salt

  • salt intake can cause high blood pressure
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Alkalis

  • Alkalis make indicators change colour
  • Alkalis neutralise acids to make salts
  • acid+alkali--->salt+water
  • the first alkali to be manufactured was calcium oxide
  • general patterns of reactions: hydroxide+acid--->salt+water
  •                                            carbonate+acid--->salt and water and carbon dioxide

The LeBlanc Process

  • made sodium carbonate by reacting salt and limestone, heated with cole
  • gave off large amounts of hydrogen chloride which is a harmful gas
  • produced lots of solid toxic waste
  • hydrogen chloride had to be changed into useful substances
  • hydrogen chloride was oxidised to make chlorine, a useful product
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Chlorine

  • chlorine is added to drinking supplies to kill microorganisms
  • chlorine is a toxic gas and can affect human health if too much is present in water
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Electrolysis

  • the breaking up of compounds through an electrical current
  • the electrolysis of brine makes chlorine gas, hydrogen gas, and sodium hydroxide solution
  • the anode is a positive electrode
  • the cathode is the negative electrode
  • brine forms at the anode and hydrogen at the cathode
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Risks of PVC

  • PVC is a plastic containing carbon, hydrogen, and chlorine
  • small molecules called plasticiser are added to PVC to make it softer
  • plasticiser molecules can leach out PVC into surroundings which may be harmful
  • plasticised PVC childrens toys have been banned in the USA and Europe
  • if PVC is burned it gives off toxic gases

Life Cycle Assessment

  • measures the energy used to make, use, and dispose of a substance and its environmental impact
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