P2-Topic 10- Using the Earth's resources and obtaining potable water

Question 1

What is sustainable development?

Answer 1

Development that meets the needs of current generations without compromising
the ability of future generations to meet their own needs

Question 2

In the UK, potable water is produced by…? 3

Answer 2

• choosing an appropriate source of fresh water
• passing the water through filter beds to remove any solids
• sterilising to kill microbe

Question 3

What are the sterilising agents
for potable water?
4

Answer 3

Sterilising agents used for potable water include chlorine, ozone or ultraviolet light.
• Chlorine is a toxic gas so the amount added to water has to be carefully
monitored.
• Using ultraviolet light to kill microbes avoids adding chemicals to the water but is more expensive

Question 4

How is desalination carried

out?2

Answer 4

by distillation or by processes that use membranes such
as reverse osmosis.

These processes require large amounts of energy.

Question 5

what are finite resources

Answer 5

resources that have a limited supply that will eventually run out

Question 6

an example of a natural product that can be replaced by a synthetic one 3

Answer 6

Rubber which is extracted from the sap of trees (called latex)
The replacement material for rubber are polymers which have been developed to specifically replace the rubber in many products

The use of fertilisers to enhance crop yield is an example of this

Question 7

What is reverse osmosis?3

Answer 7

Sea water is passed through a membrane that only allows through the water
molecules.

It needs high pressure to push the water through the membrane.

The high pressure requires a lot of energy to produce.

Question 8

What is potable water

Answer 8

water that is safe to drink

Question 9

How is wastewater produced and how is it treated? 3

Answer 9

-Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment.

• Sewage and agricultural waste water require removal of organic matter and
harmful microbes.

• Industrial waste water may require removal of organic matter and harmful chemicals.

Question 10

What are the processes involved in sewage treatment? 4

Answer 10

Sewage treatment includes:

• screening and grit removal
• sedimentation to produce sewage sludge and effluent
• anaerobic digestion of sewage sludge
• aerobic biological treatment of effluent

Question 11

What do new methods of mining avoid in terms

of disadvantages of traditional mining?

Answer 11

Avoids the disadvantages of traditional mining methods of digging, moving and disposing of large amounts of rock

Question 12

What is phytomining?

Answer 12

using plants to absorb metal compounds.

plants are harvested and then burned to produce ash that contains metal
compounds.

Question 13

What is bioleaching?

Answer 13

using bacteria to produce leachate solutions that

contain metal compounds.

Question 14

how can metal extraction be used to obtain the metal 3

Answer 14

metal compounds can be processed to obtain the metal

copper can be obtained from solutions of copper
compounds by displacement using scrap iron or by electrolysis

Question 15

What is the main advantage and disadvantage of these methods?

Answer 15

need less energy than traditional methods

can work on low concentration ores but are slow to carry out.

Question 16

Outline the key points of Haber process. Include the use of the product.6

Answer 16

a)H₂ & N₂ gases are passed over Fe catalyst at a high temperature (about 450 °C)
and a high pressure (about 200 atm) to compress gas

b) Fe speeds up the rate of reaction, so that a lower temperature could be used in the process.
c) Some of the hydrogen and nitrogen reacts to form ammonia
d) The reaction is reversible so ammonia breaks down again into nitrogen and hydrogen.
e) On cooling, the ammonia liquefies and is removed.

The remaining hydrogen and nitrogen are recycled = no waste
f) Ammonia is used for production of nitrogen-containing fertilisers.

Question 17

The Haber process uses high T and p conditions.
Explain why this is so and why this is a compromise.
2

Answer 17

• The reaction is exothermic. An optimum temperature of 450 °C is used. Using a lower temperature
would give a higher yield, but the rate of NH3
production would be too slow.
• A pressure of 200 atm is used. Using a higher pressure would give a higher yield, but would be too expensive, because of the cost of energy to produce the high pressure.

Question 18

How are compounds of nitrogen, phosphorus

and potassium used?

Answer 18

Compounds of nitrogen, phosphorus and potassium are used as fertilisers to
improve agricultural productivity. NPK fertilisers contain compounds of all three elements

Question 19

How is industrial production of

NPK fertilisers achieved?

Answer 19

Ammonia can be used to manufacture ammonium salts.

The ammonium sulfate,
phosphate, and nitrate can be produced by reaction of ammonia with the requisite
acid.

Question 20

How is the phosphate rock utilised in the production of fertilisers?

Answer 20

• Phosphate rock is reacted with nitric acid to produce phosphoric acid and
calcium nitrate.

• Phosphate rock can be reacted with sulfuric acid to produce a mixture of calcium phosphate and calcium sulfate

• Phosphate rock can be reacted with phosphoric acid to produce calcium
phosphate.