metls

• Most metals are extracted from ores found in the Earth's crust and unreactive metals are often found as the uncombined element
• The second to last element is gold (in the Reactivity Series), since it is very unreactive, it is found in the Earth as the metal itself
• But, most metals are extracted from ores found in the Earth's crust
• Extraction of a metal related to its position in the reactivity series

  1. Carbon extraction for iron

  2. Electrolysis for aluminium
• Carbon extraction


  Can only be used if the metal is less reactive than carbon, as carbon displaces the metal from the ore
• Electrolysis


  Used for metals more reactive than carbon, or those that can also be extracted this way
• Electrolysis is expensive due to the use of large amounts of energy to melt the compounds and produce the electrical current
• Extraction by heating with carbon (including iron)

  1. Iron oxide loses oxygen, and is therefore reduced. The carbon gains oxygen, and is therefore oxidised.

  2. 2Fe2O3(s) + 3C(s) -> 4Fe(l) + 3CO2(g)

  3. Carried out at high temperatures in a blast furnace
• Extraction by electrolysis (including aluminium)


  1. Metals that are more reactive than carbon e.g. aluminium are extracted by electrolysis of molten compounds.

  2. Too reactive to be extracted by reduction with carbon

  3. Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite using carbon as the positive electrode (anode).

  4. Metals that react with carbon can also be extracted by electrolysis
• Detailed knowledge of the processes used in the extraction of a specific metal is not required
• Phytoextraction


  Some plants absorb metal compounds through their roots and concentrate them, the plants can then be burned to produce an ash that contains the metal compounds
• Bacterial extraction


  Some bacteria absorb metal compounds and produce solutions called leachates which contain the metals
• Aluminium


  Low density, corrosion-resistant, used for aircraft, trains, overhead power cables, saucepans and cooking foil
• Copper


  Soft and easily bent, good conductor of electricity, does not react with water, used for electrical wiring and plumbing
• Iron


  From the blast furnace: hard, but too brittle for most uses, so converted to steel. Pure iron: too soft for many uses
• Types of steel


  • Low carbon steel: 0.25% carbon, easily shaped, car body panels
  • High carbon steel: 2.5% carbon, hard, cutting tools
  • Stainless steel: chromium & nickel, resistant to corrosion, cutlery and sinks
• An alloy is a mixture of a metal and one or more elements, usually other metals or carbon
• Most metals in everyday uses are alloys. Pure copper, gold, iron and aluminium are all too soft for everyday uses and so are mixed with small amounts of similar metals to make them harder for everyday use
• Why alloys are harder than pure metals


  In a pure metal, the ions are all the same size and in a regular arrangement of layers, allowing them to slide over each other easily, making them soft. In an alloy, there are different sized ions which disrupt the regular arrangement and prevent the layers from sliding over each other so easily.