5: Copper

Question 1

What is copper used for?

Answer 1

Electrical 65%
Construction 25%
Transport 7%
Other 3%

Question 2

Properties of copper

Answer 2

good heat conductor
good electrical conductor
ductile
unreactive compared to most metals

Question 3

Copper ores

Answer 3

Copper metal is extracted by heating crushed ore with carbon. This works because carbon is more reactive than copper.

It easily breaks down to form copper oxide when heated:
copper carbonate = copper oxide + carbon dioxide
CuCO3 = CuO + CO2

The copper oxide is then heated with carbon. This is a reduction reaction because oxygen is removed:
copper oxide + carbon = copper + carbon dioxide
2CuO + C = 2Cu + CO2

Question 4

What process is used to purify copper?

Answer 4

Electrolysis

Question 5

What is the negatively charged electrode in electrolysis?

Answer 5

The cathode

Question 6

What is the positively charged electrode in electrolysis?

Answer 6

The anode

Question 7

What happens at the cathode?

Answer 7

Copper is deposited and cathode gains mass (reduction is gain):
Cu2+ + 2e- = Cu

Question 8

What happens at the anode?

Answer 8

Copper dissolves and it loses mass (oxidation is loss):

Cu - 2e- = Cu2+

Question 9

Advantages of recycling copper

Answer 9

Makes better use of natural resources

Reduces the amount of waste and pollution produced

Question 10

Problems of recycling copper

Answer 10

Scrap metal thieves realise the value of copper, but most people do not recycle it.
They throw old electrical items away making it difficult to recover the copper for recycling because the waste items have to be sorted.