C10

Question 1

What are requirements for potable water?

Answer 1

• no microbes
• levels of dissolved minerals ie salts fairly low
• pH 6.5-8.5

Question 2

Explain how phytomining works

Answer 2

• plants are grown in soil
• the plants absorb metal ions through their roots and concentrate these ions in their cells
• the plants are harvested and burnt
• the ash left behind contains metal
  compounds which is dissolved in acid
  and then extracted in by electrolysis/displacement

Question 3

What are the advantages of alternatives to mining

Answer 3

• reduces the need to obtain new ore by mining so less natural habitats damaged
• conserves limited supplies of high-grade ores
• reduces the amount of rock waste that must be disposed of after traditional mining so less environmental damage

Question 4

Describe the process of bioleaching

Answer 4

Certain bacteria can break down low-grade ores to produce an acidic solution containing copper ions called a leachate
Can extract by displacement with iron from leachate, which is more reactive than copper or can be electrolysed

Question 5

What does it mean if a material is hard to recycle?

Answer 5

Difficult to dispose

Question 6

Give 4 reasons why copper should be recycled rather than mined

Answer 6

• less energy required to recycle
• less landfill sites used, so less waste
• less damage to environment, as mining is polluting
• copper ores are finite so will run out

Question 7

Give three reasons why a steel car body should be recycled and not reused or sent to landfill.

Answer 7

(recycling) is used to conserve energy and minimise pollution by reducing the need to quarry
(not reuse) because of rusting/corrosion so weaker metal
(not landfill) because loss of habitats, reducing use of landfills, reduce waste

Question 8

Give 4 uses of earths resources

Answer 8

• Heating/warmth
• Food
• Transport
• Shelter

Question 9

Phytomining has not been widely used to extract copper.
Suggest two reasons why

Answer 9

• High grade ores still available
• Time consuming

Question 10

What metals rust?

Answer 10

Iron/ alloys of iron eg steel

Question 11

How can you change the properties of a polymer?

Answer 11

• Change temperature
• Change pressure
• Use a different catalyst

Question 12

Suggest why poly(ethene) is easier to recycle than thermosetting polymers.

Answer 12

Melts so can be reshaped

Question 13

Give two uses of brass

Answer 13

Ornaments
Screws

Question 14

Give one use of bronze

Answer 14

Statues

Question 15

Plan an experiment to show both water and oxygen are needed for rusting

Answer 15

• three test tubes containing nails
• test tube 1 – open test tube with water
• test tube 2 – stoppered test tube with drying agent
• test tube 3 – test tube with boiled water
• test tube 3 – sealed with oil
• leave for several days
• observe results
  Results:
• test tube 1 – nail rusts
• test tube 2 – nail does not rust
• test tube 3 – nail does not rust

Question 16

How does magnesium stop rusting in steel?

Answer 16

Magnesium is more reactive than (than iron, an alloy of steel) so corrodes before steel, providing sacrificial protection

Question 17

What is the temperature and pressure needed for the Haber process?

Answer 17

450 degrees Celsius
200 atm

Question 18

Explain what happens to gases in a nuclear reactor

Answer 18

• cooled
• ammonia condenses and liquifies
• nitrogen and hydrogen are recycled

Question 19

Explain why solar may not be able to replace generation of electricity

Answer 19

Unreliable due to cloud cover
Release less energy so may not be able to meet demand meaning many would have to be built where there is a lack of space

Question 20

What is good with materials being reusable?

Answer 20

Conserves resources

Question 21

Describe how sewage is treated to remove organic matter

Answer 21

• screening and grit removal to remove large molecules
• sedimentation to produce effluent and sludge
• anaerobic digestion of (solid sewage) sludge by bacteria
• aerobic biological treatment of (liquid) effluent (aerobic digestion)

Question 22

Explain why ground water requires sterilisation before it is safe to drink

Answer 22

May contain microbes which are harmful, so sterilised to kill/destroy microbes

Question 23

Describe test for water and oxygen needed both for rusting

Answer 23

Set up the apparatus as shown in the diagram
The water in the second test tube is boiled to remove any dissolved oxygen
The oil provides a barrier to prevent oxygen diffusing into the boiled water
Calcium chloride is a drying agent in the third test tube
Leave the apparatus for a few days to give it time to react
Results:
The nail on the left rusts as it is in contact with both air (which contains oxygen) and water
The nail in the middle does not rust as it is not in contact with air
The nail on the right does not rust as it is not in contact with water (calcium chloride absorbs any water molecules present due to moisture)
The results show that both air and water must be present for rusting to occur

Question 24

Explain LCAs

Answer 24

Environmental impact of a product involving its extraction, manufacturing, useful life, disposal and transportation at each stage