1Ores
Most metals are found in rocks as compounds, often oxides. A rock with enough metal compound to be worth extracting is an ore.
ore
Lesson 23.2 notes
Extracting metals
Ores, carbon, electrolysis, and why gold and copper were used first.
2Heating with carbon
Black copper oxide heated with carbon turns into pink-brown copper. The carbon becomes carbon dioxide, which turns limewater cloudy.
extraction
3Reduction
The carbon takes the oxygen from the copper oxide. Losing oxygen is called reduction: the copper oxide is reduced.
reduction
4Carbon or electricity?
Metals below carbon can be extracted by heating with carbon. Metals above carbon need electrolysis: electricity passed through the melted compound.
electrolysis
5Iron from iron ore
Iron is made in a blast furnace by heating iron ore with coke, a form of carbon. Molten iron runs out at the bottom.
blast furnace
6A history in metals
Gold and copper were used first, then iron. Aluminium was only extracted about 200 years ago, and only became cheap with electrolysis.
7Recycling saves energy
Recycling aluminium uses about 5% of the energy needed to extract it from its ore, and it saves the ore too.
recycling
Explore: Extraction planner
Pick a metal. See where it sits in the reactivity series, how it is extracted, and when people first made it.
Common mistake: Carbon cannot extract every metal
Carbon can only take oxygen from the oxides of metals below it in the series. Aluminium oxide heated with carbon does nothing: aluminium is extracted by electrolysis.
Remember
- An ore is a rock with enough of a metal compound to be worth extracting. Gold is found as the metal itself.
- Metals below carbon can be extracted by heating their oxides with carbon: metal oxide + carbon → metal + carbon dioxide.
- Metals above carbon are extracted by electrolysis, which uses a lot of electricity. Recycling saves energy and ores.
Going further at GCSE