Alternative extraction

• Are Earth's resources of metal ores infinite or finite?

  Finite.
• What is meant by finite? 


  Finite resources will run out eventually.
• Why are new methods of extraction of copper needed?

  Copper ore is becoming scarce, only low grade ore remains.
• What is meant by 'low grade ore'?

  Ore that has a low % of metal and is not economically worthwhile extracting.
• What is meant by 'economically worthwhile'?

  When something can be obtained and sold at profit.
• Describe phytomining.

  Uses plants to absorb copper compounds.
• How are metal compounds obtained from plants?

  Plants are harvested and burned to produce metal compound containing ash
• How is the ash produced in phytoming treated?

  It is mixed with sulfuric acid to form metal compounds.
• Describe bioleaching.

  Bacteria are used to absorb metal compounds.
• How are metal compounds obtained from bacteria?

  The bacteria are reacted with sulfuric acid to form metal compounds containing leachate solution.
• How is copper obtained from metal compounds in displacement?

  The copper can be displaced from the metal compound using scrap iron.
• Why can scrap iron be used to obtain copper?

  Iron is more reactive than copper.
• How is copper obtained from metal compounds using electricity?

  Electrolysis.
• What are the advantages of phytomining and bioleaching?

  Allows extraction of copper from low grade ore. Avoids traditional mining.
• What are the disadvantages of phytomining?

  Plants grow too slowly, can be impacted negatively by poor weather and yield a small amount of copper compared to mining.
• What are the disadvantages of bioleaching?

  Yields a small amount of copper compared to mining and makes toxic leachate that is difficult to dispose of safely.
• What is corrosion?

  Destruction of materials by chemical reaction with environmental substances.
• Name a unique example of corrosion.

  Rusting of iron.
• What is required for rusting to take place?

  Iron, air (oxygen) and water.
• Briefly describe an experiment that tests rusting.

  Into three test tubes place an iron nail and compare them after several days to see which have rusted. Tube 1 should have no air, tube 2 no water and tube 3 should have both air and water.
• How can air be removed from a test tube in the rusting experiment?

  Add boiling water and seal with grease and a bung
• How can water be removed from a test tube in the rusting experiment?

  Add a drying agent and seal the tube with a bung.
• How can water and air be added to a test tube in the rusting experiment?

  Just add some water and leave the tube open to air.
• What results would you expect to find in a rusting experiment? 


  The nail in a tube of no air and the nail in a tube of no water do not rust. The nail in the tube of air and water rusts.
• What is a disadvantage of using paint to prevent rusting?

  If the paint is damaged, the iron will rust underneath
• Describe sacrificial protection.

  A more reactive metal is added to the iron to react in its place.
• Describe an example of galvanising.


  Zinc is added as a coating to iron. It is sacrificial protection and will prevent iron rusting even when scratched.
• Aluminium doesn't appear to corrode, unlike iron, why is this unusual? 


  Aluminium is more reactive than iron and should corrode faster
• Why doesn't aluminium corrode in the same way iron does?

  Aluminium reacts with oxygen to form a protective aluminium oxide layer that is strongly bound and prevents further corrosion.
• What is an alloy?

  A metal mixed with another type of metal.
• Are metals in everyday use pure or alloys?

  Alloys.
• Which metals make bronze?

  Copper and tin.
• What are the uses of bronze?

  Statues and ornaments
• Which metals make brass?

  Copper and zinc.
• What are the uses of brass?

  Water pipes, taps and door fittings.
• What are door fittings?

  Handles, hinges and knockers.
• Which metals is gold alloyed with?

  Silver, copper and zinc
• Why is gold alloyed?

  Because it is very precious, expensive and too soft when pure
• What does a carat mean?

  It is a measure of the proportion of gold in an alloy.
• What is the carat of 100% pure gold?

  24 carat.