10 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, potable water is produced by..?

Answer 2

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

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 4

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

Answer 4

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

Question 5

what is reverse osmosis?

Answer 5

sea water is passed through a membrane that only allows through the water moleucles. 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

sewage treatment includes:
- screening and grit removal
- sedimentation to produce sewage slufe and effluent
- anaerobic digestion of sewage sludge
- aerobic biological treatment of effluent

Question 7

what is bioleaching?

Answer 7

bioleaching uses bacteria to produce leachate solutions that contain metal compounds.

Question 8

what is phytomining?

Answer 8

phytominin 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 9

how are clay ceramics made?

Answer 9

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

Question 9

what are the advantages and disadvantages of recycling?

Answer 9

advtanges of recycling: less acid rain (pollution) metal ore reserves last longer/conserved energy for extraction saved less mining/quarrying less waste less landfill creates local employment
disadvantages of recycling: collection problems transport problems/cost of transport difficult to separate metal from appliances/sort

Question 10

what is the main advantage and disadvantage of these methods?

Answer 10

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

Question 10

describe the stages of LCAs

Answer 10

life cycle assessments (LCAs) are carried out to assess the environmental impact of products in each of these stages:
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during its lifetime
- disposal at the end of its useful life, including transport and distribution at each stage.

Question 10

how do we reduce the use of resources?

Answer 10

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 10

how are composites formed?

Answer 10

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

Question 10

describe the sacrificial protection

Answer 10

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

Question 11

what is corrosion and how is it prevented?

Answer 11

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 electroplanting. these methods stop the air or water coming into contact with the metal.

Question 11

describe the compounds and the uses of bronze, brass, gold and silver and copper and zinc, aluminium-magnesium and steels

Answer 11

bronze - an alloy of copper and tin, used for making statues and decorative objects.
brass - an alloy of copper and zinc used for producing water taps and door fittings.
gold used as jewellery 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.)
aluminium-magnesium alloys are low density and used in aerospace manufacturing.
steels - alloys or 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 nockel (stainless steels) are hard and resistant to corrosion.

Question 12

how are the properties of poltmers determined?

Answer 12

the properties of 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) and produced from ethene, using different catalysts and reaction conditions.

Question 12

describe the structures of thermosoftening and thermosetting polymers

Answer 12

thermosetting polymers do not melt on heating. the polymer molecules are linked to each other by strong cross-links. thermosoftening poltmers 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 12

how is glass made?

Answer 12

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 13

key stages of Haber process:

Answer 13

a) the purified H2 and N2 gases are passed over Fe catalyst at a high temperature (about 450°C) and a high pressure (about 200 atm)
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. N2 + 3 H2 ⇌ 2 NH3.
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. this means almost no material is wasted.
f) ammonia is used for production of nitrogen-containinng fertilisers.

Question 14

the Haber process uses high T and p conditions. explain why this is so and why this is a compromise.

Answer 14

the conditions are a compromise between rate and the yield:
- 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 15

how are compounds of nitrogen, phosphorus and potassium used?

Answer 15

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

Question 16

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

Answer 16

• phosphate rock is reacted with nitric acid to produce phosphoric acid and calcium nitrate.
• phosphate rock can be reached 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.

Question 17

how is industrial production of NPK fertilisers achieved?

Answer 17

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.
2 NH3 + H2SO4 –> (NH4)2SO4
2 NH3 + H3PO4 –> (NH4)3PO4
NH3 + HNO3 –> NH4NO3
nitric acid is itself made from ammonia