10 Using resources Flashcards
what is a composite material
- made of one material embedded in another
- have a matrix which is the binder
examples of composite materials
- fibreglass - consists of fibres of glass embeded in polymer, low density but very strong used for skis, boats and surfboards
- carbon fibres - also have polymer matrix, reinforcment is from long chains of C atoms or from C nanotubes, very strong and light used in aerospace and sports car manafacturing
- concrete made of aggregate embeded in cemenet, very strong ideal for building material
what is a thermo-setting polymers
- contain monomers that can form cross-links between polymer chains holding them together in a solid structure
- don’t soften when heated
- strong hard and rigid
what are thermo-softening polymers
- contain individual polymer chains entwined together with weak forces between the chains
- can melt these plastics and remould them
difference between low density (LD) polymers and high density
(HD)
- LD is made from etehene at moderate temperatures under high pressure and with a catalyst, flexible and used for bags and bottles
- HD made from ethene but at a lower temperature and pressure with a different catalyst, more rigid, used for water tanks and drainpipes
properties of ceramics
glass and clay ceramics eg. porcelain and bricks
- insulators of heat and electricity
- brittle and stiff
properties of polymers
- insulators of heat and elctricty
- can be flexible and easily moulded - thermosoftening
- used in clothing and as insulators in electrical items
porperties of composites
- depend on the matrix/bider and the reinforcement used to make them
- have many different uses
- fibre glass, carbon fibre, concrete, wood
properties of metals
- malleable
- good conductors of heat and electricty
- ductile can be drawn into wires
- have many uses eg. electrical wires, car body-work and cutlery
how are alloys made
- adding another element to the metal
- disrupts the structure of the metal making alloys harder than pure metals
examples of alloys
- bronze = copper + tin, used in medals, decorative ornaments and statues
- brass = copper + zinc, used where lower friction needs eg. water taps, door fittings
- gold alloys, zinc, silver and copper used to allow gold to be used in jewlerry pure gold too soft
- aluminium alloys, used in aircrafts
what is the equation for the formation of rust
iron + oxygen + water —> hydrated iron(III) oxide
what is corrosion
where metals react with substance in their environment and are gradually destroyed
what happens when iron is exposed to oxygen and water
- it rusts
- flakes off the surface leaving more iron to rust and corrode
what happens when aluminium is exposed to air
- forms aluminium oxide on the outer layer of the aluminium creating a protective layer
- prevents any further corrosion taking place
what type of methods are there to prevent corrosion
- barrier method
- sacraficial method
- some methods use both eg. an object can be galavanised by spraying a coat of zinc - firstly protective but if scratched zinc around the site of the scratch works as sacraficial metal
barrier methods for preventing corrosion
- painting/coating with plastic
- electroplating - uses electrolysis to reduce metal ions onto an iron electrode, can be used to coat iron with a layer of a different metal that won’t corrode
- oiling/greasing - has to be used when moving parts involved eg. bike chains
sacrificial methods to prevent corrosion
- involves placing a more reactiev metal such as zinc or magensium with the iron
- water and oxygen react with the sacrifical metal instead of with the iron
- used on boats
what are natural resources
- form without human input
- includes anything made from earth, sea or air
- some can be replaced with synthetic products or improved by man-made processes
- Agricluture provides conditions where natural resources can be enchanced for our needs
what are renewable resources
- reform at a similiar rate or faster than we use them
- eg, fresh water, food, timber
what are non-renewabele sources
- aren’t formed quickly enough to be considered replacable
- finite
- fossil fuels, nuclear fields, minerals and metals found in ores in the earth
- afte rextracted many go under man-made process eg. fractional distilation
what is sustainable development
- approach to development that takes account of needs of present society while not damaging the lives of future generations
how can we extract copper
b
- bioleaching - bacteria used to convert copper compounds in the ore into soluble copper compunds, seperating out coper from the ore in the process
- the lechate (solution produced by the process) contains copper ions which can be extracted though elecotrolysis or displacement
how can we extract copper
p
- involves growing plants in soil that contains copper
- plants can’t use or get rid of the copper so it gradually builds up in the leaves
- plants can be harvested, dried and burned in a furnace
- the ash contains soluble copper compounds which copper can be extracted through electrolysis or displacemnt
why is recycling metals important
- use much less energy that needed to mine and extract new metal
- conserves the finite amount of each metal in the earth
- cuts down in amount of waste getting sent to landfill
how can we recylce metals
- melting them and casting them into shape of the new product
- depending on what the metal will be used for, the amount of speration required from recyclable metals metals can change
how to write a life cyle assessment
- getting the raw material - damage on environment for extraction, how much it costs
- manafacture and packaging - amount of enrgy used, any waste products and hwo to dispose of them
- using the product - ho wlong it will last for, how many uses it gets, does use fo product damage the environment
- product disposal - where will the be disposed - landfil?, energy used ot dispose them, products may get incincerated causing air pollution
what are the problems with life cycle assesments
- th use of energy, sme naturla resources and amount of certain types of waste produced by a porduct ovdf its lifetime can be easily quanitied by effcect of pollutants is harder
- nto an objective mthod as it takes into accoutn the valies of the perosn carryign out the assessment - so LCA’s can be biased
- Selectiev LCAs will show only some of the impacts of a porduct on the enviornemtn, cna be deliberatly writtein to suport claims of a company to hive them positive advertising
what is potabel water
- water that’s beem treated or is naturally safe for humans to drink
- not pure! pure water only has H2O molecules
- has a pH between 6.5 and 8.5
how is potable water produced
filtration
- a wire mesh screens out large large twigs
- gravel and sand beds filter out any other solid bits
- sterilisation - water is sterilized to kill any bacteria and microbes
- can be done by bubbling chlornr gas, usign ozone or shining UV light
how is potabel water produced
disillation
used in dry areas where insteas there is sea water
- first test oH of water usning a pH meter, if too high or too low you need to neutralise it
- test the water for presence of sodium chloride using a flame test and halide test
- to distil the water pour the salty water into a distilation aparatus
- heat flash from below, water boils and forms steam leaving dissolved salts in flask
- steam condenses back to liquid water in condenser and can be collected as it runs out
- rtest the distilled water for sodium chloride and pH of water
how else can potable water be produced
- reverse osmosis
- salty water passed through a membrane rhat only allows water molecu;es to pass through
- ions and large molecules trapped by membrane so seperate from water
- requires a lot of energy so very expensive
how do we treat sewage
- Water is passed through a mesh screen
to remove large bits e.g twigs or grit - Chemicals are added to make solids and
microbes stick together to form
sediment and sink leaving a sludge on top - Effluent is remobved an treated by biological aerobic digestion - air is pumped through the water to encourage aerobic bacteria to break down any organic matter
- Sewage is removed and transfered into large tanks where it gets broken down by bacteria in anaerbobic digestion
- During anaerobic digestion organic matter in the sludge is broken down releasing methane gas which can be used as an energy source and remaining waste can be used as fertiliser
- The water is then sterilised with chemicals eg. chlorine or UV radiation to kill any microbes left.
what does the harber process produce
nitrogen + hydrogen <—> ammonia
N2+ 3H2 <—> 2NH3
describe the harber process
- nitgoen and hydrogen are passed over an iron catalyst
- 450 degrees and 200 atmsopheres used
- as ammonia cools down it condense and liquifies and is removes
- since reversibel some ammonai will convert back to hydrogen and nitrogen
- any gas that onverted back or didn’t react gets recycled
- ammonia produced can be used to make ammonium nitrate - nitrgoegn rich fertiliser
what compromises are made in the harber process
- 450 degrees - forward reaction is ecothermic so if temp increased more reactant woudl be produced ratehr than ammonia however at low temperatures the reaction would be slower, 450 is a compromise between maximum yield and speed of reactio
- 200 atmospheres - higher pressure means more forward reaction since 4 molecules on left for every 2 on the right, pressure set as high as possibel without makign it too expensive
what are fertilisers
- formulations which contain Nitrogen, phosphorus and pottasium which help plants to increase crop yield as crops can grow faster and bigger
what are NPK fertilisers
- formulations containign salts of nitrogen, phosphorus and pottasium in the right precentages
ammonium nitrate symbol+word equation
NH3 +HNO3 —> NH4NO3
Nitrogen + Nitric acid —> Ammonium nitrate
how is ammonium nitrate produced in industry
- carreid out in giant vats at high concentrations rslultign in a very expthermic reaction
- heat released evaporates water from the mixture - makes very concentrated ammonia nitrate
how is ammonium nitrate produced in a lab
- carried out on a small scale
- through titration and crystilistaion
- reactants are at a much lower concentration so less heat is produced by the reactoin and it’s safer for a person to carry out
- after titration the mixture needs to be crstalised to give pure ammonium nitrate crystas
- crystilisation isn’t used in inidstry because it’s very slow