GCSE COMBINED SCIENCE: TRILOGY Higher Tier Chemistry Paper 1H

This question is about the extraction of aluminium.
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An aluminium atom is represented as:
Al1327
Give the number of electrons and neutrons in the aluminium atom.
[2 marks]
Number of electrons
Number of neutrons
Aluminium is extracted by the electrolysis of a molten mixture of aluminium oxide
and cryolite.
Figure 1 shows the cell used for the electrolysis.
Figure 1
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Aluminium is produced by the reduction of aluminium oxide (Al2O3).
What is meant by the term reduction?
[1 mark]
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Oxygen is formed at the positive carbon electrodes.
Explain why the positive carbon electrodes must be continually replaced.
[3 marks]
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A substance conducts electricity because of free moving, charged particles.
What are the free moving, charged particles in a:
• carbon electrode (made from graphite)
• molten mixture of aluminium oxide and cryolite
• metal wire?
[3 marks]
Carbon electrode (made from graphite)
Molten mixture of aluminium oxide and cryolite
Metal wire
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This question is about substances with covalent bonding.
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Figure 2 shows a ball and stick model of a water molecule (H2O).
Figure 2
Suggest one limitation of using a ball and stick model for a water molecule.