Covalent Structures: Electric Motor
Unit C2, C2.2.3
Covalent structures
1.
This drill contains an electric motor.
The diagram below shows the main parts of an electric motor.
The carbon contacts are made of graphite. Springs push the contacts against the copper ring.
The contacts conduct electricity to the copper ring. The copper ring rotates rapidly but does not stick or become worn because the graphite is soft and slippery.
Graphite has properties which are ideal for making the contacts in an electric motor.
Explain, in terms of structure and bonding, why graphite has these properties.
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(Total 5 marks)
Page 1 of 4
Unit C2, C2.2.3
2.
Bricks made from silica (silicon dioxide) are used to line furnaces that operate at high temperatures. Part of the structure of silica is shown in the diagram.
Suggest and explain why silica is
Covalent structures
1.
This drill contains an electric motor.
The diagram below shows the main parts of an electric motor.
The carbon contacts are made of graphite. Springs push the contacts against the copper ring.
The contacts conduct electricity to the copper ring. The copper ring rotates rapidly but does not stick or become worn because the graphite is soft and slippery.
Graphite has properties which are ideal for making the contacts in an electric motor.
Explain, in terms of structure and bonding, why graphite has these properties.
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
(Total 5 marks)
Page 1 of 4
Unit C2, C2.2.3
2.
Bricks made from silica (silicon dioxide) are used to line furnaces that operate at high temperatures. Part of the structure of silica is shown in the diagram.
Suggest and explain why silica is