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2.5Inorganic Chemistry

Extraction and Uses of Metals — Edexcel Linear - OL (Chemistry) Revision Notes & Topical Questions

5 min read 8 parts Lesson 12 of 23 Unit quiz

📚 Edexcel Linear - OL (Chemistry) Hub / Topical Revision
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Curriculum Equation Key معادلة تفاعل تكوين الإستر (الأسترة) - Esterification Reaction EquationFast Exam Solution
R-COOH + R2-OH ⇌ (conc. H₂SO₄) R-COO-R2 + H₂O
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Location & Specifications: الكيمياء العضوية للثانوية العامة والتحصيلي و Edexcel Chemistry.
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Lesson summary

Extraction and Uses of Metals — EDEXCEL LINEAR – OL (CHEMISTRY) notes: Explain how the position of a metal in the reactivity series determines its extraction method and relate the properties of metals and alloys to their uses.An ore is a rock that contains enough of a metal compo…

  • Worked example 1
  • Worked example 2
  • Worked example 3
  • Worked example 4
  • Electrolysis
  • Coke burns: C + O2 → CO2 (exothermic, gives heat)

Part 1 of 6Ores and choosing a method

An ore is a rock that contains enough of a metal compound for extraction to be economic.

Unreactive metals such as gold and platinum occur native.
Reduced
Most metals are found as oxides, sulfides or carbonates and have to be reduced.
The reactivity series decides the method: metals above carbon hold on to oxygen too strongly for carbon to remove it,
  • so electrolysis is needed; metals below carbon can be obtained by heating the oxide with carbon.
    • (or carbon monoxide)
Sulfide ores are usually roasted in air first to give the oxide, and carbonates are heated to give the oxide.

Part 2 of 6Iron: the blast furnace

Raw materials are iron ore (haematite, Fe2O3), coke (carbon), limestone (calcium carbonate) and hot air. Reactions:

1
Coke burns: C + O2 → CO2 (exothermic, gives heat).
2
Carbon dioxide is reduced: CO2 + C → 2CO.
3
Iron(III) oxide is reduced: Fe2O3 + 3CO → 2Fe + 3CO2.
4
Limestone decomposes: CaCO3 → CaO + CO2; then CaO + SiO2 → CaSiO3 (slag).

Molten iron (denser) collects at the bottom beneath the slag; both are tapped separately. Waste gases mainly nitrogen and carbon dioxide leave at the top. Cast iron from the furnace contains about 4% carbon and is brittle. Converting it to steel removes impurities by blowing oxygen through the molten iron and adding controlled amounts of carbon and other metals.

Part 3 of 6Aluminium: electrolysis

Aluminium oxide (from bauxite) has a very high melting point (about 2000 °C), so it is dissolved in molten cryolite at about 950 °C to save energy and cost.

1
The electrolysis uses graphite electrodes.
2
At the cathode: Al3+ + 3e- → Al (reduction); molten aluminium sinks and is tapped.
3
At the anode: 2O2- → O2 + 4e- (oxidation).
4
The oxygen reacts with the hot graphite anodes to make carbon dioxide, so the anodes burn away and must be replaced.
5
The process uses huge amounts of electricity, so plants are sited near cheap power.

Copper is purified by electrolysis

  • the impure copper is the anode and a pure copper strip the cathode in copper(II) sulfate solution.
  • Copper dissolves from the anode (Cu → Cu2+ + 2e-) and plates the cathode, leaving impurities as sludge.

Part 4 of 6Uses, alloys and recycling

Metal / alloyKey propertiesUses
AluminiumLow density, corrosion resistant, good conductorAircraft, cans, cables
CopperExcellent conductor, ductile, unreactiveWires, pipes
Mild steelStrong, cheap, malleableCar bodies, construction
Stainless steelRust resistantCutlery, equipment
Brass (Cu + Zn)Harder than copper, corrosion resistantTaps, musical instruments

Recycling metals conserves ores, saves energy (recycling aluminium needs only about 5% of the energy used in extraction) and reduces waste, but needs collection and sorting.

Part 5 of 6Comparing extraction methods

Compare the three processes by what is reduced, how, and the cost.

FeatureIronAluminiumCopper (purification)
Starting materialHaematiteBauxite → Al2O3Impure copper
Reducing methodCarbon monoxideElectrolysisElectrolysis
Main energy costCoke burningElectricity (very high)Electricity (moderate)
Environmental problemCO2 emission, slagCO2 from anodes, miningMining waste, sludge

Choosing a method in an examstate the position relative to carbon, name the process, and then give the key equation or electrode reaction.

Part 6 of 6Worked examples

  1. Why can zinc oxide be reduced by carbon but magnesium oxide cannot? [2]2 marks

  2. Write the equation for the formation of slag in the blast furnace. [2]2 marks

  3. Explain why the anodes in aluminium extraction have to be replaced. [2]2 marks

  4. Describe how copper is purified by electrolysis. [4]4 marks

Key terms

TermMeaning
OreRock containing a metal compound that can be profitably extracted
SlagCalcium silicate that removes impurities from molten iron
CryoliteCompound that lowers the melting point of aluminium oxide
ElectrolysisDecomposition of a molten or dissolved ionic compound by electricity
SteelAlloy of iron with controlled carbon
BauxiteOre from which aluminium oxide is obtained
RecyclingReusing metals instead of extracting them from ores

Avoid these mistakes

1
Saying carbon is a reactant at the cathode in aluminium extraction — electrolysis uses electricity, not carbon, to reduce Al3+.
2
Forgetting that the blast furnace reduction is by carbon monoxide.
3
Saying limestone reduces iron oxide — it forms slag with silica.
4
Confusing oxidation at the anode and reduction at the cathode.

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