Extraction of Metals and Reduction
Practise Extraction of Metals and Reduction for GCSE Chemistry with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Metals less reactive than carbon can be extracted from their oxides by reduction with carbon.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Most metals are found in the Earth as compounds, usually oxides, and must be extracted by chemical reactions. Only very unreactive metals such as gold are found as the metal itself.
The method depends on the metal's position relative to carbon in the reactivity series. Metals less reactive than carbon can be extracted by reduction with carbon, which removes the oxygen. Iron is extracted this way in a blast furnace.
Metals more reactive than carbon must be extracted by electrolysis, because carbon is not reactive enough to displace them. Aluminium is extracted this way. Electrolysis requires large amounts of energy and is therefore expensive.
Revision notes
Extraction with carbon
Metals less reactive than carbon can be extracted by reduction with carbon.
The carbon removes the oxygen from the metal oxide. For example: iron oxide + carbon → iron + carbon dioxide. This is a reduction reaction because the metal oxide loses oxygen.
Extraction by electrolysis
Metals more reactive than carbon must be extracted by electrolysis of the molten compound.
Carbon cannot displace them because it is less reactive. Aluminium is extracted this way. The process needs a great deal of energy so is expensive.
Unreactive metals
Gold and other very unreactive metals are found in the Earth as the metal itself, not as compounds.
They require no chemical extraction, only physical separation from the surrounding rock.
Key points
- Most metals are found as compounds, usually oxides.
- Gold is found as the metal itself.
- Metals below carbon are extracted by reduction with carbon.
- Reduction removes oxygen from the metal oxide.
- Metals above carbon are extracted by electrolysis.
- Electrolysis is expensive because it uses much energy.
Worked examples
Example 1
Explain why aluminium cannot be extracted using carbon. [2 marks]
Model answer
Aluminium is more reactive than carbon (1 mark), so carbon cannot displace it from its oxide and electrolysis must be used instead (1 mark).
Example 2
Explain why extracting iron with carbon is described as a reduction reaction. [2 marks]
Model answer
The iron oxide loses its oxygen to the carbon (1 mark), and reduction is defined as the loss of oxygen (1 mark).
Example 3
Explain why gold is found in the Earth as the metal itself. [2 marks]
Model answer
Gold is very unreactive (1 mark), so it does not react with other elements to form compounds (1 mark).
Common mistakes
Saying all metals are extracted with carbon.
Only those below carbon in the reactivity series can be.
Forgetting why electrolysis is used.
It is because carbon is not reactive enough to displace the metal.
Saying extraction is oxidation.
Removing oxygen from a metal oxide is reduction.
Not mentioning cost.
Electrolysis requires large amounts of energy, which is a key evaluation point.
Exam tips
- Compare the metal's position with carbon before choosing a method.
- Say reduction and explain it as loss of oxygen.
- Mention the high energy cost of electrolysis.
- Learn iron and aluminium as your two examples.
Key terms
- Extraction
- Obtaining a metal from its compound.
- Reduction
- The loss of oxygen from a compound.
- Electrolysis
- Using electricity to break down a compound.
- Ore
- A rock containing a metal compound worth extracting.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.