Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

3.2.3Atomic Structure and the Periodic Table

Extraction of Metals

5 min read 4 parts Lesson 1 of 10 Unit quiz

0%read

Section 1 of 4Choosing an Extraction Method

3.2.3 Extraction of Metals

The position of a metal in the reactivity series decides how it can be obtained from its compounds.

Native metals
  • Unreactive metals such as gold are often found uncombined, so they do not need chemical extraction.
Ores
  • Most metals are chemically combined in ores, which are rocks containing enough of the metal to be worth extracting.
Reduction with carbon
  • Metals less reactive than carbon can be extracted by reducing their oxides with carbon or carbon monoxide.
Electrolysis
  • Metals more reactive than carbon, such as aluminium, must be extracted by electrolysis of a molten compound.

Section 2 of 4The Blast Furnace

Iron is extracted in a blast furnace, which works in three zones with a clear set of reactions.

1
Coke burns in hot air to produce carbon dioxide and heat: C(s) + O₂(g) → CO₂(g).
2
At high temperature the carbon dioxide reacts with more coke to form carbon monoxide: CO₂(g) + C(s) → 2CO(g).
3
Carbon monoxide reduces iron(III) oxide to molten iron, which collects at the bottom: Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g).
4
Limestone decomposes to calcium oxide, which reacts with silicon dioxide impurities to form a slag that floats on the molten iron.

Section 3 of 4Extracting Aluminium by Electrolysis

Extracting Aluminium by Electrolysis
Purification
  • Bauxite is first purified to produce aluminium oxide, Al₂O₃.
Cryolite
  • Aluminium oxide is dissolved in molten cryolite, which lowers the melting point and saves energy.
Cathode
  • Aluminium ions gain electrons to form molten aluminium: Al³⁺ + 3e⁻ → Al, which is siphoned off.
Anode
  • Oxide ions lose electrons to form oxygen, which reacts with the carbon anodes so they wear away and must be replaced.

Section 4 of 4Exam Checklist & Tips

3.2.3 – Key Points for the Exam

  • Ore A rock containing enough of a metal compound to make extraction worthwhile.
  • Reduction A reaction in which oxygen is removed from a compound, or electrons are gained.
  • Blast furnace A furnace in which iron is produced from iron ore, coke and limestone.
  • Cryolite A substance used to lower the melting point of aluminium oxide during electrolysis.

Common Mistakes

  • Stating that carbon can extract aluminium; aluminium is more reactive than carbon, so electrolysis is needed.
  • Confusing the roles of cokeit burns to supply heat and also produces carbon monoxide, the reducing agent.
  • Forgetting that limestone is added to remove acidic silicon dioxide impurities from the ore.
  • Saying that molten aluminium forms at the anode; it forms at the cathode, while oxygen forms at the anode.
\n