topic 5 : seperate chemistry I

• electroplating is using electricity to put a thin layer of metal on an object
• the cathode is used as the object and the anode is used as the plating material
• an alloy is a mixture of two or more metals
• alloys disrupt the regular lattice structure so layers of atom cannot slide over each other, making it stronger
• aluminium is used to make electricity cables as its a good conductor of heat and iron is used in washing machines as its resistant to rusting
• the actual yield is always less than the theoretical yield as there can be incomplete reactions, practical losses during the experiment, side reactions
• properties of transition metals:

  High melting point

  High density

  have ions with many different charges

  Form coloured compounds

  Are useful as catalysts
• a particular reaction pathway is chosen to produce a specified product:

  a high atom economy

  high yield

  fast rate

  equilibrium position to the right

  useful by-products
• equilibrium is reached at a faster rate when:

  a higher temperature is used

  a higher pressure/concentration is used

  a catalyst is used
• Chemical reactions stop when one of the reactants has been used up
• electroplating acts as a barrier in order to exclude oxygen and water

  -it can also improve the appearance
• uses of metals:

  -aluminium- low density, used for aircraft

  -copper-good conductor, used in electrical cables

  -gold- good resistance to corrosion, used in jewellery

  • magnalium- low density, used in cars and planes

  -brass- hard, resistant to corrosion, used in coins
• dynamic equilibrium: forward and back reactions take place at the same time and there is no observable change