AQA Chemistry 5.4.1.3
Extraction of metals and reduction
Where a metal sits compared with carbon decides how we get it out of its ore. Below carbon: heat with carbon, and the oxide is reduced. Above carbon: electrolysis.
Combined Science · Higher tier
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Gold and iron, underground.
Gold jewellery stays shiny for centuries. An iron gate left outside goes rusty within a year or two.
If you had to guess, which metal would you expect to find in the ground as the metal itself?
Above or below carbon?
Carbon decides the method.
Most metals are found as compounds, in ores, and need chemical reactions to extract the metal. Metals less reactive than carbon can be extracted from their oxides by heating with carbon. Metals more reactive than carbon are extracted by electrolysis of a molten compound, which needs a lot of energy. Pick a metal and choose.
How is iron obtained?
0 of 5 metals placed correctly
How electrolysis extracts aluminium is its own lesson. Here you only need the contrast.
Reduced and oxidised
Lose oxygen: reduced. Gain oxygen: oxidised.
Reduction involves the loss of oxygen. When a metal oxide is heated with carbon, the oxide loses oxygen and is reduced; the carbon gains that oxygen and is oxidised. The worked example is first; then you tag the other two.
Reduced
Copper oxide: it loses its oxygen and becomes copper.
Oxidised
Carbon: it gains oxygen and becomes carbon dioxide.
Think again · it has oxygen, so it’s oxidised?
“Zinc oxide is oxidised, because it has oxygen in it.”
Your call
IdentifyZinc oxide is heated with carbon to make zinc and carbon dioxide. Which substance is reduced?
Sort
How is it extracted?
Place each metal, or its compound, by method.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Identify
- Which substance loses oxygen (reduced) and which gains it (oxidised).
- Explain
- Compare the metal with carbon, then give the method.
- Interpret
- Use the information you are given about a process; you don’t need to have learned its details.
Key fact
Metals less reactive than carbon can be extracted from their oxides by reduction with carbon. Reduction involves the loss of oxygen.
Key note · AQA 5.4.1.3
Extraction of metals and reduction
- Unreactive metals such as gold are found in the Earth as the metal itself.
- Most metals are found as compounds, in ores, and need chemical reactions to extract them.
- Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
- Reduction is the loss of oxygen; oxidation is the gain of oxygen. In 2CuO + C, copper oxide is reduced and carbon is oxidised.
- Metals more reactive than carbon are extracted by electrolysis of a molten compound, which needs a lot of energy.
- You may be given information about a process to interpret; its details do not need to be learned.
Photograph this card. Tomorrow, cover it and say each line first.
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Not sure which substance is reduced?
The ladder shows the metals needed for this lesson, with carbon marked for reference.