Topic 4 of 6 · Form 4
Metals and their extraction
K, Na, Ca, Mg, Al, (C), Zn, Fe, Pb, (H), Cu, Ag, Au. More reactive metals displace less reactive ones from solutions of their salts, e.g. Zn + CuSO₄ → ZnSO₄ + Cu.
Notes for this topic 1 file, in order
Create a free account to download PDFs.
Reactivity series
K, Na, Ca, Mg, Al, (C), Zn, Fe, Pb, (H), Cu, Ag, Au. More reactive metals displace less reactive ones from solutions of their salts, e.g. Zn + CuSO₄ → ZnSO₄ + Cu.
Extraction
The method depends on reactivity:
- Above carbon: electrolysis of the molten ore (aluminium, sodium).
- Below carbon: reduction with carbon or carbon monoxide (iron, zinc, lead).
- Very unreactive: found as the metal (gold).
The blast furnace (iron)
Raw materials: iron ore (haematite, Fe₂O₃), coke and limestone.
- C + O₂ → CO₂; then CO₂ + C → 2CO
- Fe₂O₃ + 3CO → 2Fe + 3CO₂
- Limestone decomposes to CaO, which reacts with sand (SiO₂) to form slag (CaSiO₃), removing impurities.
Alloys and uses
Steel (iron with carbon) is stronger; stainless steel resists rusting; brass (copper and zinc). Aluminium is light and resists corrosion (oxide layer) – used for aircraft and pots. Copper conducts well – used for wiring.
Rusting
Iron needs water and oxygen to rust. Prevention: painting, greasing, galvanising, sacrificial protection with a more reactive metal (zinc or magnesium).
Check yourself
- Why is aluminium extracted by electrolysis, not by carbon?
- State the role of limestone in the blast furnace.
- Explain why galvanised iron does not rust even when scratched.
Show answers
- Aluminium is more reactive than carbon, so carbon cannot reduce its oxide.
- It removes impurities (sand) as slag.
- Zinc is more reactive and corrodes in preference to iron (sacrificial protection).
Questions about this topic (0)
No questions about this topic yet.
Sign in or create a free account to join in.