C14 The Earth's Resources

Question 1

two types of natural resources

Answer 1

finite
renewable

Question 2

what are renewable natural resources

Answer 2

natural resources that can be replaced at the same rate that they are used up

Question 3

what are finite natural resources

Answer 3

natural resources used up faster than they can be replaced

Question 4

what is potable water

Answer 4

water that is fit to drink

Question 5

steps to produce potable water

Answer 5

1. pass untreated water through filter beds made of gravel/sand to remove solid particles,
2. passes through a screen to remove large objects like twigs,
3. passes through settlement tank so soil and sand settle out,
4. add aluminium sulphate and lime so dirt clumps together and sinks to the bottom for separation,
5. add chlorine/ozone or pass through ultraviolet to kill harmful microorganisms (sterilise)
6. check pH is neutral and store in reservoirs

Question 6

why is water passed over ultraviolet or chlorine/ozone added

Answer 6

to kill harmful microorganisms/sterilise

Question 7

what is desalination?

Answer 7

turning salty water usable and potable

Question 8

two methods of salivation

Answer 8

distillation
reverse osmosis

Question 9

summarise energy costs for distillation as desalination

Answer 9

expensive, a lot of money needed to boil so much water
even with reduced pressure

Question 10

summarise costs for reverse osmosis as desalination

Answer 10

no money needed for heating
however expensive to pressurise the water
and replace corroded water pumps

Question 11

four main steps of sewage treatment

Answer 11

1. screening and grit removal to remove large particles
2. sedimentation so tiny particles settle out of the still water, leaving sludge and effluent (liquid layer on top)
3. sewage sludge is anaerobically digested by specific bacteria
4. effluent is treated with aerobic bacteria to reduce volume of solid waste

Question 12

what is done with extra sludge from sewage treatment?

Answer 12

• used as fertiliser,
• dried out into a ‘cake’ used to provide electricity

Question 13

how is sludge digested during sewage treatment?

Answer 13

anaerobically by specific bacteria

Question 14

how is effluent treated during sewage treatment?

Answer 14

with aerobic bacteria to reduce the volume of solid waste

Question 15

two methods of obtaining copper metal from ore

Answer 15

1. smelting: heat copper ore to form impure copper, then electrolyse it,
2. use sulphuric acid to produce copper sulphate solution then displacing the copper from this with iron.

Question 16

what is the aim of bioleaching and phytomining?

Answer 16

to extract copper from low-grade ores

Question 17

how is copper obtained from bioleaching

Answer 17

plants absorb copper compounds,
the plants are harvested and then burned
to produce ash that contains copper compounds
which can be displaced by iron and electrolysed to obtain pure copper

Question 18

how is copper obtained from phytomining

Answer 18

bacteria feed on low-grade metal ores
to produce leachate solutions that contain metal compounds
which can be obtained by displacement by iron and electrolysis

Question 19

what is a Life Cycle Assessment?

Answer 19

a technique to assess the environmental impact of a process, product or service from the point of getting the raw materials to when they are disposed back into the environment

Question 20

stages of a product/process/service considered in a LCA?

Answer 20

• extracting and processing raw materials,
• manufacture and packaging,
• use and operation during its lifetime,
• disposal at the end of its useful life, including transport and distribution.

Question 21

environmental impacts of quarrying and mining

Answer 21

• damages animal habitats, stressing ecosystems,
• scarring landscape and causing noise,
• making groundwater acidic,