extraction of ores

• Where are most metals extracted from?

  From ores found in the Earth’s crust.
• What is an ore?

  A rock which contains metals
• Which metals are found in the earth’s crust as uncombined elements?

  Unreactive metals.
• Explain what oxidation means in terms of oxygen.

  Gain of oxygen.
• Explain what reduction means in terms of oxygen.


  Loss of oxygen.
• Most ores contain metals chemically combined with oxygen. What process must be carried out to extract the metal?

  Reduction.
• Which two methods could be used to extract metals from their ores?

  • Reduction with carbon: Can only be done if the metal is less reactive than carbon.
  • Electrolysis: Can be done with all metals, but requires a large amount of energy (high cost).
• How would you extract iron from its ore?

  Iron is less reactive than carbon so can be extracted by reduction with carbon.
• How can aluminium be extracted from its ore?

  Aluminium is more reactive than carbon so electrolysis must be used.
• When aluminium is extracted from aluminium oxide, why is it first dissolved in molten cryolite?

  To produce an electrolyte with a lower melting point, reducing energy usage and cost.