Metals and their extractions

• Ores


  Minerals found in the Earth's crust that contain metal compounds, from which metals can be extracted
• Name of ore

  • rock salt
  • bauxite
• Reactivity series

  Method used to extract metals from their ores depends on the reactivity of the metal. Allows us to predict how metals will react.
• Reactivity series (decreasing)

  • Potassium
  • Sodium
  • Magnesium
  • Aluminium
  • (Carbon)
  • Zinc
  • Iron
  • Tin
  • Lead
  • Copper
  • Silver
  • Gold
• Metals found native

  • Gold and silver
• Extraction method

  Most reactive metals extracted by electrolysis, those towards the middle of the reactivity series can be chemically reduced
• Displacement reaction


  A more reactive metal will displace a less reactive metal from a solution of one of its salts
• Competition reaction


  A more reactive metal will remove oxygen from the oxide of a less reactive metal when a mixture of the two is heated
• Transition metals


  Found in the centre of the Periodic Table, display typical metallic properties, can form more than one type of ion, compounds are often coloured
• Testing for transition metal ions

  Use a solution of sodium hydroxide
• Transition metal ion tests

  • Cu2+(aq) + 2OH–(aq) → Cu(OH)2(s) (blue precipitate)
  • Fe2+(aq) + 2OH–(aq) → Fe(OH)2(s) (green precipitate)
  • Fe3+(aq) + 2OH–(aq) → Fe(OH)3(s) (orange/brown precipitate)
• Alloy


  Mixture made by mixing molten metals, properties can be modified by changing composition
• Types of steel

  • Mild steel (iron plus 0.15-0.3% carbon - malleable, ductile, easily shaped)
  • High carbon steel (iron plus 0.7-1.5% carbon - harder but more brittle)
• Blast furnace

  1. Iron ore, limestone and coke are added

  2. Oxygen from hot air reacts with carbon (coke) to form carbon monoxide (exothermic)

  3. Carbon monoxide reacts with iron(III) oxide to give iron

  4. Limestone decomposes to form calcium oxide which reacts with silicon dioxide to form slag
• Oxidation and reduction in blast furnace

  Iron(III) oxide is reduced whilst the carbon monoxide is oxidised
• Electrolysis


  Process of breaking down an ionic compound using electrical energy
• Electrolyte


  Liquid which is broken down by an electrical charge
• Electrode


  Graphite rods which carry a current in and out of the electrolyte
• Cathode


  Negative electrode
• Anode


  Positive electrode
• Oxidation


  Gain of electrons
• Aluminium electrolysis

  1. Aluminium oxide dissolves in molten cryolite at a lower temperature

  2. At cathode: Al3+ + 3é → Al

  3. At anode: 2O2– – 4é → O2 (reacts with carbon anodes, forming CO2 and requiring anodes to be replaced)
• Aluminium plant location factors

  • Near coast to import raw materials
  • Away from built up areas
  • Near town/city to accommodate workforce
  • Good transport links
  • Direct electricity supply
• Iron (steel)


  • Strong and hard
• Aluminium


  • Strong, low density, good conductor of heat and electricity, resistant to corrosion
• Copper


  • Very good conductor of heat and electricity, malleable and ductile, attractive colour and lustre
• Titanium


  • Hard, strong, low density, resistant to corrosion, high melting point
• Transition metals

  The elements found in the central area of the periodic table
• The majority of transition metals have the following properties in common:
• Properties of transition metals

  • They form coloured compounds
  • They are good conductors of heat and electricity
  • They are malleable, ie can be hammered or bent into shape easily
  • They are less reactive than alkali metals, such as sodium
  • They have high melting points – but mercury is a liquid at room temperature
  • They are usually hard and tough
  • They usually have high densities
  • They can form ions with different charges
• Oxidation


  The loss of electrons from a substance. It is also the gain of oxygen by a substance.
• Reduction


  The gain of electrons by a substance. It is also the loss of oxygen from a substance.
• Oxidation and reduction take place at the same time in a reaction. We call this type of reaction a redox reaction.
• Oxidising agent


  The chemical that causes oxidation by providing oxygen
• Reducing agent


  The chemical that causes the other chemical to be reduced by removing oxygen
• Thermite reaction


  • aluminium + iron(III) oxide → iron + aluminium oxide
• Aluminium has been oxidised. This means that the iron(III) oxide is the oxidising agent. The iron(III) oxide has been reduced. This means that the aluminium is the reducing agent.
• Blast furnace


  A huge container used to extract iron from iron ore
• Raw materials for the blast furnace

  • Iron ore (haematite)
  • Coke
  • Limestone
  • Air
• Reactions in the blast furnace

  1. Hot air (oxygen) reacts with the coke (carbon) to produce carbon dioxide and heat energy

  2. More coke is added to the furnace and reduces the carbon dioxide into carbon monoxide, a good reducing agent

  3. Iron(III) oxide is reduced to iron