- Metals more reactive than carbon (e.g. Al, Na, Ca, K) must be extracted by electrolysis.
- Metals less reactive than carbon (e.g. Fe, Zn, Cu) can be extracted by carbon reduction.
- Gold is so unreactive it is found native — no extraction needed.
- Iron is extracted from haematite (Fe₂O₃) in a blast furnace.
- Aluminium is extracted from bauxite (Al₂O₃) dissolved in cryolite.
- Cryolite lowers the melting point of Al₂O₃ from ~2050°C to ~970°C, saving energy.
- At the cathode: Al³⁺ ions are reduced (gain electrons) → aluminium metal forms.
- At the anode: O²⁻ ions are oxidised (lose electrons) → oxygen gas forms; carbon anodes burn and must be replaced.
- Electrolysis uses more energy than carbon reduction, so aluminium is more expensive to produce than iron.
- Bioleaching and phytomining are used for low-grade copper ores with less environmental damage.
This key facts covers Key Facts within Extracting Metals for GCSE Chemistry. Revise Extracting Metals in Chemical Changes for GCSE Chemistry with 6 exam-style questions and 6 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 9 of 14 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Extracting Metals
Which method is used to extract a metal that is MORE reactive than carbon?
Iron is extracted from haematite in a blast furnace. Describe how iron is obtained from iron oxide using carbon, and explain the term 'reduction' in this context.
Quick recall flashcards
What is haematite, and where is iron extracted from it?
Haematite is iron oxide (Fe₂O₃) — the main ore of iron. Iron is extracted from haematite in a blast furnace using carbon (coke) as the reducing agent.
Which metals must be extracted by electrolysis, and why?
Metals MORE reactive than carbon (e.g. aluminium, sodium, potassium) must be extracted by electrolysis. Carbon is not reactive enough to pull oxygen away from them.