chemistry C1 (3)

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What is an ore?

  • most metals are usually found combined with other elements, often oxygen, in rocks
  • to be able to use the metal, it must be chemically separated form its compounds
  • the rock is called an ore if it contains enough of the metal or metal compound to make it economically worthwhile to extract the metal
  • ores are mined and may be concentrated before the metal is extracted and purified
  • concentrating an ore involves the removal of waste rock from the mined ore
  • which makes the extraction process more economical
  • extracting a metal from its ore is expensive because the process requires a lot of energy so there must be a significant amount of the metal or metal compound to make this worthwhile
  • iron ore is haematite
  • aluminium ore is bauxite
  • lead ore is galena
  • copper ore is malachite

Which metals can be extracted using carbon?

  • metals that can be extracted using carbon are: lead, zinc, iron, copper
  • metals that cannot be extracted using carbon: aluminium, sodium
  • iron and copper are both below carbon in the reactivity series, so carbon con be used to reduce the oxides and obtain the metal
  • copper oxide + carbon to copper + carbon dioxide
  • 2CuO + C to 2Cu + CO2
  • iron oxide + carbon to iron + carbon dioxide
  • 2Fe2O3 + 3C to 4Fe + 3CO2
  • reduction: removal of oxygen from a compound
  • ore: a rock containing enough metal to make it economical to extract
  • reactivity series: a list of metals from the most reactive to the least reactive
  • native: unreactive metals (such as silver, gold and platinum) found as elements in nature

The extraction of metals from their ores

  • metal compounds are found in rocks called ores
  • the commonest metal compounds found are metal carbonates, metal sulfides or metal oxides
  • when metal carbonates are heated, they decompose to give the solid metal oxide and the gas, carbon dioxide, is given off
  • when metal sulfides are heated in air they react with the oxygen in the air
  • the products of this reaction are the solid metal oxide and the gas, sulfur dioxide
  • if the metal is less reactive than carbon, then carbon will reduce the metal oxide to the metal
  • when the metal oxide is heated with carbon, then carbon dioxide is formed along with the metal
  • metal carbonate is heated and gives off carbon dioixde to from metal oxide
  • metal sulfide is heated and gives off sulfur dioxide to form metal oxide
  • the metal oxide is heated with carbon and gives off carbon dioxide the result is metal

Iron and steels

  • iron is extracted from iron ore, containing iron(III)oxide, by reducing in a blast furnace
  • in a blast furnace, the potassium manganate(VII), KMnO4, at the bottom of the tube produces oxygen gas when it is heated that is used in the reaction
  • in the reaction you have just seen, the iron(III) oxide has been reduced to produce iron
  • industrially, iron is extracted from iron ore called haematite which is mostly iron(III) oxide


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