T10 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 (safe to drink) water is produced by…

Answer 2

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

Question 3

what are the sterilising agents for potable water

Answer 3

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

distillation or by processes that use membranes such as reverse osmosis

processes require large amounts of energy

Question 5

what is reverse osmosis

Answer 5

sea water is passes through a membrane that only allows through the water molecules

needs high pressure to push the water through the membrane

the high pressure requires a lot of energy to produce

Question 6

how is housewater produced and how is it treated

Answer 6

• urban lifestyles and industrial processes produce large amounts of waste water that requires 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 of traditional mining methods of digging, moving and disposing of large amount of rock

Question 9

what is phytomining

Answer 9

uses plants to absorb metal compounds from the soil

plants are harvested and then burnt to produce ash that contains the metal compounds

Question 10

what is bioleaching

Answer 10

uses bacteria to produce leachate solutions that contain metal compounds

Question 11

advantages and disadvantages of these methods

Answer 11

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

Question 12

describe the stages of LCAs

Answer 12

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 13

how do we reduce the use of resources

Answer 13

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

Question 14

advantages and disadvantages of recycling

Answer 14

less acid rain (pollution), metal ore reserves last longer, less landfill, creates employment

collection problems, cost of transport, difficult to sort

Question 15

what is corrosion and how is it prevented

Answer 15

destruction of chemical reactions with substances in the environment

applying a coating that acts as a barrier, such as greasing, painting or electroplating - stop the air or water coming into contact with the metal

Question 16

describe the sacrificial process

Answer 16

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

Question 17

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

Answer 17

alloys:
bz - copper + tin, used for making statues, decorative objects

br - copper + zinc, used for producing water taps and door fittings

G - used as jewellery, alloy with silver, copper and zinc

AM - low density, used in aerospace manufacturing

S - iron that contain specific amounts of carbon and other metals. High carbon steel is strong but brittle. Low is softer and more easily shaped. Steel containing chromium and nickel (stainless steels) are hard and resistant to corrosion

Question 18

how are the properties of polymers determined

Answer 18

depend on what monomers they are made from and the conditions under which they are made

ex. low density and high density poly(ethene) are produced from ethene, using different catalysts and reaction conditions

Question 19

describe the structures of thermosoftening and thermosetting polymers

Answer 19

sett - don’t melt on heating, polymer molecules are linked to each other by strong cross-links

sof - soften easily on heating and can then be remoulded, keeping the new shape on cooling, polymer molecules are attracted to each other by weak intermolecular forces

Question 20

how is glass made

Answer 20

most is soda-lime, 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 21

how are clay ceramics made

Answer 21

shaping wet clay and then heating in a furnace

Question 22

how are composites formed

Answer 22

fibres or fragments of one material (reinforcement) are surrounded by a binder/matrix materials that holds these fibres/fragments together

Question 23

outline the key points of Haber process

include the use of the product

Answer 23

1. purified H2 and N2 gases are passed over Fe catalyst at high temperature (450C) and a high pressure (200 atm)
2. Fe speeds up the rate of reaction, so that a lower temperature could be used in the process
3. some of the hydrogen and nitrogen reacts to form ammonia
   N2 + 3H2 >< 2NH3
4. reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
5. on cooling, ammonia liquefies and is removed. Remaining hydrogen and nitrogen are recycled, no material wasted
6. ammonia is used for production of nitrogen-containing fertilisers

Question 24

Haber process uses high T and P conditions

Explain why this is so and why this is a compromise

Answer 24

compromise between rate and the yield

• reaction is exothermic, optimum temp is used (450), lower temp would give higher yield, but the rate of NH3 production would be too slow
• pressure of 200 used, higher pressure would give higher yield, too expensive tho due to cost of energy to produce the high pressure

Question 25

how are compounds of nitrogen, phosphorus and potassium used

Answer 25

fertilisers to improve agricultural productivity

NPK fertilisers contain compounds of all three elements

Question 26

how is industrial production of NPK fertilisers achieved

Answer 26

ammonium can be used to manufacture ammonium salts

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

Question 27

how is phosphate rock utilised in the production of fertilisers

Answer 27

• reacted with nitric acid to produce phosphoric acid and calcium nitrate
• can be reacted with sulfuric acid to produce a mixture of calcium phosphate and calcium sulfate
• can be reacted with phosphoric acid to produce calcium phosphate