Metals and uses of metals- paper 2

• Most metals are extracted from ores found in earth's crust and unreactive metals are often found as uncombined element
• How do you extract a metal that is more reactive than carbon?

  electrolysis
• Why is electrolysis expensive?

  cryolite is expensive, requires lots of energy, replacement of electrodes required regularly
• How would you extract a metal less reactive than carbon?

  reduction of carbon so carbon displaces the metal
• What do you have to add for electrolysis in aluminium oxide?

  cryolite
• What does cryolite do?

  lowers melting point
• Why does aluminium need to be liquid for electrolysis?

  so ions are free to move and can be attracted to electrodes
• WHy do we use cryolite in electrolysis of aluminium?

  reduce costs by lowering temperature
• What gas is given off from the electrode in aluminium extraction?

  carbon dioxide
• State a problem with electrolysis?

  contributes to global warning as carbon dioxide is a greenhouse gas
• What does panic stand for?

  positive anode negative is cathode
• What does a cathode attract?

  positive ions
• What does cathode attract in electrolysis?

  aluminium ions
• What does an anode attract?

  negative ions
• What does an anode attract in electrolysis?

  oxide ions
• What is the half equation for aluminium electrolysis?

  Al3+ + 3e- = Al
• What is the half equation for oxide in electrolysis?

  202- - 4e- = 02
• What is the use of aluminium and why?

  aircrafts, saucepans because of low density and resistant to corrosion
• What is the use of copper and why?

  electrical wiring as soft, easily bent, good conductor, doesn't react with water
• Why can't you use iron from the blast furnace?

  too brittle
• What happens with the iron from blast furnaces?

  converted to steel
• What is the use of low carbon steel and why?

  car body panels as easily shaped
• What is the use of high carbon steel and why?

  cutting tools as hard
• What is the use of stainless steel and why?

  cutlery as resistance to corrosion
• Why are alloys harder than pure metals?

  impure, all metals are same size in regular arrangement so can slide over each other so soft, in alloy different sized ions so no regular arrangement and layers can't slide easily
• What are the anodes and cathodes made of in electrolysis?

  graphite
• How is carbon dioxide formed in electrolysis?

  oxygen from anode reacts with carbon from cathode
• Why in terms of its structure is aluminium ductile?

  layers of ions slide over each other
• Explain in terms of structure why aluminium is a good conductor of electricity?

  delocalised electrons can carry electricity through structure
• Why is aluminium good for aircraft bodies?

  low density
• Describe how carbon dioxide is formed in electrolysis?

  oxygen formed and reacts with carbon on electrode