C2: Metals and Alloys

C2: Metals and Alloys

1. Extracting Copper

   • Impure copper can be purified using electrolysis.
     • Impure copper is the anode and a sheet of pure copper is used for the cathode.
       • Positive anode loses mass as copper dissolves.
         • Anode- Cu atoms loss electrons to form CU2+ ions (oxidation).
       • Negative cathode gains mass as pure copper is plated onto it.
         • Cathode- copper is plated when CU2+ ions gain electrons (reduction).
   • Advantages of recycling copper: 1) fairly low melting point so low cost, 2) reduces the need for mining- saving reserves and environmental problems, 3) keeps costs down.
   • Disadvantages of recycling copper: 1) small amounts used in electrical equipment are difficult to separate, 2) pure copper scrap must not be mixed with less pure scrap, 3) less copper is mined so less jobs, 4) separating process may cause pollution, 5) lots is thrown away as it is difficult to get people to recycle it.
   • Concentration stays the same because the impure copper dissolves and the pure coppers is plated at the same rate.

2. Alloys

   • Mixtures containing at least one metal.
   • Amalgam- contains mercury (filling teeth).
   • Brass- contains copper and zinc (locks).
   • Solder- contains lead and tin (soldering).
   • Some smart alloys return to their original shape after being heated at certain temperatures.
     • Nitinol- used to make glasses frames.