Extracting iron and aluminium
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The teaching part (2 min) is free to watch. A free account opens the whole lecture: 2 worked examples, 5 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Two big metals, two big methods
- Iron: the raw materials
- The reactions, step by step
- Removing the impurities
Read the transcript of the teaching part
Last time
Before we start: last time, in Alloys and rust protection, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Two big metals, two big methods
Your bicycle, your fridge and your car all contain iron or aluminium. Iron is below carbon in the reactivity series, so it is made in a blast furnace by heating with carbon. Aluminium is above carbon, so it needs electricity. The two methods are both big industry, and both are examined every year.
Iron: the raw materials
The iron ore is haematite, which is iron(III) oxide, Fe 2 O 3. Coke is carbon. It is the fuel, and it is also used to make the reducing agent. Limestone is calcium carbonate, which is used to remove impurities. Hot air supplies the oxygen.
The reactions, step by step
Step one: coke burns in the hot air. C plus O 2 gives CO 2. This is exothermic and heats the furnace. Step two: carbon dioxide reacts with more coke to make carbon monoxide. CO 2 plus C gives 2CO. Step three: carbon monoxide reduces the iron(III) oxide. Fe 2 O 3 plus 3CO gives 2Fe plus 3CO 2.
Removing the impurities
The ore contains impurities such as silicon dioxide, which is acidic and has a high melting point. Limestone decomposes in the heat: CaCO 3 gives CaO plus CO 2. The calcium oxide is a base. It reacts with the silicon dioxide to give calcium silicate, called slag. CaO plus SiO 2 gives CaSiO 3.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Blast furnace extraction of iron · Extraction of aluminium by electrolysis · Extraction of iron.
Chapter 9: Metals
- The reactivity series 5 min
- Displacement reactions and extraction 5 min
- Extracting iron and aluminium 6 min
- Alloys and rust protection 5 min
Also for IGCSE Chemistry 0620
Which topics come up most in IGCSE Chemistry 0620 past papers, counted from every paper since 2004.