T10 using resources Flashcards
what is sustainable development
development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
in the UK, potable (safe to drink) water is produced by…
- choosing an appropriate source of fresh water
- passing the water through filter beds to remove any solids
- sterilising to kill microbes
what are the sterilising agents 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
how is desalination carried out
distillation or by processes that use membranes such as reverse osmosis
processes require large amounts of energy
what is reverse osmosis
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
how is housewater produced and how is it treated
- 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
what are the processes involved in sewage treatment
- screening and grit removal
- sedimentation to produce sewage sludge and effluent
- anaerobic digestion of sewage sludge
- aerobic biological treatment of effluent
what do new methods of mining avoid in terms of disadvantages of traditional mining
avoids the disadvantages of traditional mining methods of digging, moving and disposing of large amount of rock
what is phytomining
uses plants to absorb metal compounds from the soil
plants are harvested and then burnt to produce ash that contains the metal compounds
what is bioleaching
uses bacteria to produce leachate solutions that contain metal compounds
advantages and disadvantages of these methods
need less energy than traditional methods and can work on low concentration ores but are slow to carry out
describe the stages of LCAs
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
how do we reduce the use of resources
reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, energy consumption, waste and environmental impacts
advantages and disadvantages of recycling
less acid rain (pollution), metal ore reserves last longer, less landfill, creates employment
collection problems, cost of transport, difficult to sort
what is corrosion and how is it prevented
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
describe the sacrificial process
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
describe the compounds and the uses of bronze, brass, gold, aluminium-magnesium, steels
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
how are the properties of polymers determined
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
describe the structures of thermosoftening and thermosetting polymers
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
how is glass made
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
how are clay ceramics made
shaping wet clay and then heating in a furnace
how are composites formed
fibres or fragments of one material (reinforcement) are surrounded by a binder/matrix materials that holds these fibres/fragments together
outline the key points of Haber process
include the use of the product
- purified H2 and N2 gases are passed over Fe catalyst at high temperature (450C) and a high pressure (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 + 3H2 >< 2NH3 - reaction is reversible so ammonia breaks down again into nitrogen and hydrogen
- on cooling, ammonia liquefies and is removed. Remaining hydrogen and nitrogen are recycled, no material wasted
- ammonia is used for production of nitrogen-containing fertilisers
Haber process uses high T and P conditions
Explain why this is so and why this is a compromise
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
