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ChemistryInternational GCSEEdexcel & Cambridge IGCSEYears 10–11

IGCSE Chemistry Metals and Extraction Notes

How a metal is extracted depends on its position in the reactivity series. Reactive metals need electrolysis; less reactive metals are reduced by carbon.

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Key concepts

Reactivity series
Order of metals by reactivity: K, Na, Ca, Mg, Al, C, Zn, Fe, H, Cu, Ag, Au.
Reduction
Loss of oxygen or gain of electrons — how metals are freed from ores.
Blast furnace (iron)
Iron ore + coke + limestone; CO reduces Fe₂O₃ to Fe; slag removes impurities.
Electrolysis (aluminium)
Molten Al₂O₃ dissolved in cryolite; Al forms at the cathode, O₂ at the anode.
  • Metals above carbon are extracted by electrolysis; metals below carbon are extracted by reduction with carbon.
  • Rusting needs both oxygen AND water; prevented by painting, oiling, galvanising or sacrificial protection.
  • Alloys are harder than pure metals because different-sized atoms disrupt sliding layers.
  • In the blast furnace: 2C + O₂ → 2CO, then Fe₂O₃ + 3CO → 2Fe + 3CO₂.

Worked example

Explain why aluminium is extracted by electrolysis, not by reduction with carbon.

  1. 1Aluminium is above carbon in the reactivity series.
  2. 2So carbon is not reactive enough to displace it from Al₂O₃.
  3. 3Electrolysis provides enough energy to reduce Al³⁺ ions to aluminium metal.

Answer: Aluminium is too reactive to be reduced by carbon, so electrolysis is used.

Common mistakes

✗ Saying iron is 'melted' from its ore.

✓ Iron is chemically reduced (oxygen removed), not just melted.

✗ Forgetting cryolite in aluminium extraction.

✓ Cryolite lowers the melting point of Al₂O₃, saving energy.

✗ Confusing sacrificial protection with barrier methods.

✓ Sacrificial metal is more reactive and corrodes instead of iron; a barrier (paint) just keeps water/oxygen out.

Quick check

Try these, then reveal the answers.

What is reduced in the blast furnace?Reveal answer

Iron(III) oxide, Fe₂O₃.

Why is aluminium suitable for aircraft?Reveal answer

Low density, corrosion resistant (forms protective oxide layer), strong when alloyed.

What two things must be present for iron to rust?Reveal answer

Oxygen and water.

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Exam tips

  • Use position in the reactivity series to decide extraction method — this is a common exam question.
  • Learn the three key blast furnace equations.
  • For rust prevention, name the method AND briefly say how it works.

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Key terms explained

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Frequently asked questions

What is an ore?+

A rock that contains enough of a metal compound to make extracting the metal economically worthwhile.

Why is aluminium more expensive than iron?+

Electrolysis of aluminium uses huge amounts of electrical energy, which costs much more than reducing iron with carbon.

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