GCSE: OCR gateway: C2: metals and alloys + making cars

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  • C2
    • Metals and Alloys
      • Extracting Copper
        • Impure copper can be purified with electrolysis
        • Advantages of recycling copper
          • Fairly low melting point so low cost to melt it down
          • Reduces mining needs
            • Saves reasources
            • Stops environment related problems occuring
          • Keeps the cost of copper down
        • Disadvantages of recycling copper
          • Small amounts in electrical equipment are difficult to separate
          • Pure copper cannot be mixed with less pure materials .e.g solder
          • Less copper mined so less mining jobs
          • Seperating proccess may cause pollution
          • A lot of copper is thrown away so it is difficult to persuade peopel to recycle it
        • Electrolysis
          • In the purification of copper an electrolyte of copper is used; copper sulfate solution
            • The concentration of copper sulfate solution stays the same as the impure anode dissolves and the pure cathode gains at the same rate
          • Impure copper is the anode and pure copper is the cathode
            • The positive anode loses mass as the copper dissolves
            • Negative cathode gains mass as pure copper is plated onto it
          • At the anode Cu atoms lose electrons to become Cu2+ ions; oxidation
            • Cu - 2e- = Cu2+
          • At the cathode copper is plate when Cu2+ ions gain electrons; reduction
            • Cu2+ + 2e- = Cu
      • Alloys
        • Mixtures containing at least one metal
        • Uses
          • Amalgam has mercury and is used for teeth fillings
          • Brass has copper and zinc
          • Solder has lead and tin
        • Smart alloys return to their origional shape when heated to a certain temperature
          • Nitinol is used to make spectical frame; it returns to it origional shape when put into hot water
            • Smart alloys becoming more important as we are finding new ways to use them
    • Making cars
      • Rusting and corrosion
        • Only iron and steel rust; other meatals corrode
        • Acid rain and salt water accelerate rusting
        • Rusting is an oxidation reaction as iron reactes with oxygen to form an oxid
          • Iron + oxygen + water = hydrated iron oxide
        • Aliminium does not corrod in moist air as it has a protective layer of alimium oxide which unlike rust does not flake off the surface
        • Different metals corrode at different rates
      • Materials in Cars
        • Alloys are used
          • Steel as it is stronger and harder than iron
          • Steel is less likely to corrode than iron
        • Car bodies are built from ether aluminium or steel
          • Aluminium is lighter and more resistant to corrosion
            • Lighter body means better fuel economy and less corrosion means car body will last for longer
          • Steel costs less and is stronger
      • Recycling
        • Advantages of recycling old cars
          • Less mining saves finite reasources need to make metals
          • Less crude oil needed to make new plastics
          • Less waste so less landfill
          • Fewer toxic materials (lead from batteries) are dumped
        • Disadvantages of recycling old cars
          • Fewer mines built and fewer mining jobs
          • Difficult to seperate materials
          • Some seperating techniques cause pollution
          • Some recycling proccesses are very expensive
        • There are laws which make sure a minimum percentage of all car manufacturing materials must be recycled to help protect the environment

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