Using Resources

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, how is potable water produced?

Answer 2

• choose an appropriate source of fresh water
• pass the water through filter beds to remove any solids
• sterilise to kill microbes

Question 3

What are the sterilising agents for potable water?

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 must be carefully monitored
- using ultraviolet light to kill microbes avoids adding chemicals to the water, but it’s more expensive

Question 4

How is desalination carried out?

Answer 4

desalination can be done by distillation or by processes that use membranes such as reverse osmosis, these processes require large amounts of energy

Question 5

What is reverse osmosis?

Answer 5

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 6

How is wastewater produced and how is it treated?

Answer 6

• 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 7

What are the processes involved in sewage treatment?

Answer 7

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

Question 8

What do new methods of mining avoid in terms of disadvantages of traditional mining?

Answer 8

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

Question 9

What is phytomining?

Answer 9

phytomining uses plants to absorb metal compounds from the soil, the plants are harvested and then burned to produce ash that contains the metal compounds

Question 10

What is bioleaching?

Answer 10

bioleaching uses bacteria to produce leachate solutions that contain metal compounds

Question 11

What is the main advantage and disadvantage of these methods (phytomining and bioleaching)?

Answer 11

these methods need less energy than traditional methods and can work on low concentration ores, but are slow to carry out

Question 15

How do we reduce the use of resources?

Answer 15

the reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, energy consumption, waste and environmental impacts

Question 15

What are the advantages and disadvantages of recycling?

Answer 15

advantages:
- less acid rain (pollution)
- metal ore reserves last longer
- conserved energy for extraction saved
- less mining/quarrying
- less waste
- less landfill (sorry, pmt doesn’t believe in grammar)
- creates local employment

disadvantages:
- collection problems
- transport problems
- cost of transport
- difficult to separate metal from appliances

Question 15

Describe the stages on LCAs

Answer 15

LCAs are carried out to assess the environmental impact of products in each of these stages (EMUD)

Question 16

What is corrosion and how is it prevented?

Answer 16

corrosion is the destruction of materials by chemical reactions with substances in the environment, e.g. rusting

corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating. these methods stop the air or water coming into contact with the metal

Question 17

Describe sacrificial protection

Answer 17

some coatings are reactive and may contain corrosion inhibitors or a more reactive metal
if 2 metals are in contact the more reactive metal will corrode instead of the less reactive one, e.g. zinc is used to galvanise iron and when scratched, provides sacrificial protection because zinc is more reactive than iron

Question 18

Describe the compounds and the use of bronze

Answer 18

bronze - an alloy of copper and tin, used for making statues and decorative objects

Question 19

Describe the compounds and the use of brass

Answer 19

an alloy of copper and zinc used for producing water taps and door fittings

Question 20

Describe the compounds and the use of gold, silver, copper & zinc

Answer 20

gold used as jewelry is usually an alloy with silver, copper and zinc (the proportion of gold in the alloy is measured in carats, with pure gold being 24 carat, e.g. 18 carat gold is 75% gold)

Question 21

Describe the compounds and the use of aluminum-magnesium

Answer 21

aluminum-magnesium alloys are low density and used in aerospace and manufacturing

Question 22

Describe the compounds and the use of steels

Answer 22

alloys of iron that contain specific amounts of carbon and other metals, high carbon steel is strong but brittle, low carbon steel is softer and more easily shaped, steels containing chromium and nickel (stainless steels) are hard and resistant to corrosion

Question 23

How are the properties of polymers determined?

Answer 23

the properties on polymers depend on what monomers they are made from and the conditions under which they are made
for example; low density (LD) and high density (HD) poly(ethene) are produced from ethene, using different catalysts and reaction conditions

Question 24

Describe the structures of thermosoftening and thermosetting polymers

Answer 24

thermosetting polymers do not melt on heating, the polymer molecules are linked to each other by strong cross-links
thermosoftening poymers soften easily on heating and can then be remoulded, keeping the new shape on cooling. the polymer molecules are attracted to each other by weak intermolecular forces

Question 25

How is glass made?

Answer 25

most of the glass we use is soda-lime glass, made by heating a mixture of sand, sodium carbonate and limestone. borosilicate glass, made from sand and boron trioxide, melts at higher temperatures than soda-lime glass

Question 26

How are clay ceramics made?

Answer 26

clay ceramics, including pottery and bricks, are made by shaping wet clay and then heating in a furnace

Question 27

How are composites formed?

Answer 27

fibres or fragments of one material (reinforcement) are surrounded by a binder/matrix material that holds the fibres/fragments together
e.g. fibreglass - glass fibres bound together in a polymer, used for making storage tanks

Question 28

Outline the key points of Haber process, include the use of the product

Answer 28

• the purified H2 and N2 gases are passed over Fe cataylst at a high temperature (about 450 celcius) and a high pressure (about 200 atm)
• Fe speeds up the rate of reaction, so that a lower temperature could be used in the process
• some of the hydrogen and nitrogen reacts to form ammonia N2 + 3 H2 –><– 2 NH3
• the reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
• on cooling, the ammonia liquefies and is removed, the remaining hydrogen and nitrogen are recycled, this means almost no material is wasted
• ammonia is used for production of nitrogen-containing fertilisers

Question 29

The Haber process uses high T and p conditions, explain why this is so and why this is a compromise

Answer 29

the conditions are a compromise between the rate and the yield
- the reaction is exothermic, an optimum temperature of 450 celcius 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 30

How are compounds of nitrogen, phosphorus and potassium used?

Answer 30

compounds of nitrogen, phosophorus and potassiu are used as fertilisers to improve agricultural productivity, NPK fertilisers contain compounds of all 3 elements

Question 31

How is industrial production of NPK fertilisrs achieved?

Answer 31

ammonia can be used to manufacture ammonium salts, the ammonium sulfatem ohosphate and nitrate can be produced by reaction of ammonia with the requisite acid

2 NH3 + H2SO4 –> (NH4)2SO4
2 NH3 + H3PO4 –> (NH4)3PO4
NH3 + HNO3 –> NH4NO3

Question 32

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

Answer 32

• 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