Metals and their extraction

• What is an ore?

  A rock that contains enough of a metal compound to make extraction economically worthwhile.
• How are metals typically extracted from their ores?

  Using chemical reactions such as reduction with carbon, electrolysis, or displacement.
• Why is gold found in its native state in the Earth’s crust?

  Because it is unreactive and does not easily form compounds.
• What is the general trend between a metal’s reactivity and the difficulty of its extraction?

  The more reactive the metal, the more difficult and costly it is to extract.
• What is a displacement reaction?

  A more reactive metal displaces a less reactive metal from its compound.
• Give an example of a displacement reaction involving iron and copper.

  Iron + Copper(II) chloride → Iron chloride + Copper
• What is the thermit reaction used for?

  To extract iron using aluminium as the reducing agent: Aluminium + Iron(III) oxide → Aluminium oxide + Iron
• Define oxidation in terms of oxygen.

  Gain of oxygen.
• Define reduction in terms of oxygen.

  Loss of oxygen.
• Name the raw materials used in the blast furnace.

  Iron ore (haematite), coke (carbon), and limestone.
• What does OIL RIG stand for in redox reactions?

  Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
• Why is cryolite used in aluminium extraction?

  It lowers the melting point of alumina, reducing energy costs.
• List two properties and uses of aluminium.

  Lightweight and corrosion-resistant; used in aircraft and cans.
• What colour precipitate forms Cu2+

  Blue precipitate.
• What colour precipitate forms with Fe2+

  Pale green precipitate
• What colour precipitate forms with Fe³⁺

  Rusty brown precipitate.
• What is an alloy?

  A mixture of metals (or a metal and another element), designed to have improved properties.
• What are the three products of brine electrolysis?

  Hydrogen gas, chlorine gas, and sodium hydroxide.
• What are uses of electrolysis?

  Electroplating, purifying copper, and making sodium hydroxide, hydrogen, and chlorine.
• Name four factors that affect the economic viability of metal extraction.

  Energy costs; Fuel availability; Greenhouse gas emissions; Location of plant and recycling
• Rock salt

  Sodium chloride
• Bauxite

  Aluminium oxide
• Reactivity of metals

  • Potassium
  • Sodium
  • Magnesium
  • Aluminium
  • (Carbon)
  • Zinc
  • Iron
  • Tin
  • Lead
  • Copper
  • Silver
  • Gold
• Coke

  A fuel added to a blast furnace to produce carbon monoxide for the reduction
• Why is limestone added to the blast furnace?

  To remove impurities
• Why is hot air added to the blast furnace?

  Provides oxygen so that coke can burn
• $2C+$$O_2\rightarrow2CO$


  Oxygen from hot air reacting with carbon (coke) to form carbon monoxide
• $Fe_2O_3+$$3CO\rightarrow2Fe+$$3CO_2$


  Carbon monoxide reacting with Iron (III) oxide to give Iron
• $CaCO_3\rightarrow CaO+$$CO_2$


  Limestone decomposes thermally to form calcium oxide
• $CaO+$$SiO_2\rightarrow CaSiO_3$


  Calcium reacts with silicon dioxide to form slag
• $Fe_2O_3+$$3CO\rightarrow2Fe+$$3CO_2$


  Oxidation and reduction equation. Iron oxide reduces, Carbon Monoxide is oxidised