C14 Flashcards
what are the 2 main ways to class resources
finite and infinite (renewable)
define finite resources
a resource which will eventually run out
define renewable resource
a resource which will never run out because it can be replenished at the rate it is used up
what are some natural resources which are used and the alternate synthetic product made
wool - clothes - acrylic fibre
cotton - clothes - polyester
silk - clothes - nylon
linseed oil - paint - acrylic resin
rubber - tyres - synthetic polymers
wood - construction - PVC
what does natural water contain
- insoluble impurities
- soluble impurities
- biological impurities
what is potable water
water that is safe to drink
how do methods of collecting potable water vary in each country
it depends on the available supplies of water and the local conditions
how does the UK gather potable water
rain water provides water with low levels of dissolved substances which is then collected into lakes and rivers
how is most potable water produced
- choosing an appropriate source of fresh water
- passing the water through filter beds
- steralising
what are some sterilising agents used in potable water
- chlorine
- UV light
- ozone
what is the water treatment process of fresh sources of potable water
- filter beds remove large objects
- sand and soil becomes settled and fall to the bottom of the settlement tank
- aluminium sulphate and lime are added which causes small particles of dirt to clump together and fall to the ground. this forms a sludge which is then taken to landfill
- the water is passed through a filter of fine sand so any remaining mud or grit is removed
- the water is sterilised by chlorine
- the pH of the water is checked and corrected to it’s neutralised
- the water is stored in large tanks till needed
- the water is pumped to where it is needed
what is pure water
water which only contains water particles
how can water be purified
by desalinisation
why is pure water used
it is used for experiments in labs by chemists
is pure water safe to drink
no, as our bodies will start to become deficient in some ions
what is desalinisation
the process of removing salt from sea water
what is the problem with desalinisation
it uses a vast amount of energy
what are the 2 methods of desalinisation
- reverse osmosis
- distillation
what is reverse osmosis
where sea water is passed through a membrane. The membrane has small pores which is big enough to allow water to pass but the salt is too big and so can not pass through the membrane and so gets trapped.
what are the advantages and disadvantages of reverse osmosis
- most minerals and ions can not pass through the small pores
- expensive membranes are required and produces large amounts of waste water
why is there large amounts of waste water
due to urban lifestyles
what happens to the waste water before being released into the environment
it is treated
what does sewage and agricultural waste water require removal of
- organic matter
- harmful microbes
what does industrial waste water require removal of
- organic matter
- harmful chemicals
what are the steps to sewage treatment
- sewage arrives at the pumping station
- the sewage is screened to remove large solid objects
- Primary treatment - solid sediments settle down forming a sludge at the bottom of the tank. this sludge is pushed to another area. the effluent at the top is moved to the next area
- secondary treatment - useful bacteria feed on the remaining organic matter and other harmful organisms, breaking them down aerobically.
- final treatment - the useful bacteria settle down at the bottom of the tank as sediment . water is safe but can be filtered one more time using chlorine.
how can sewage sludge be treated
- it can be separated and dried off to be used as fertiliser
- it can be digested anaerobically by microorganisms
what is an ore
a naturally occurring rock where metal or metal compounds are concentrated enough to be economical to extract
what properties of copper make it useful
- ductile - useful for wiring
- good conductor of heat and electricity
- unreactive - does not react with water
what are the 2 main ways to extract copper
- using sulphuric acid
- smelting and then electrolysis
how does sulphuric acid work when extracting copper
sulphuric acid is added to make copper sulphate solution, before extracting the copper metal. Iron scraps are added to the copper sulphate. The Iron displaces the copper in the copper sulphate.
how doe smelting work when extracting copper
copper ore is heated to a high temperature in a furnace with air to make impure copper. The impure copper is used as the positive electrode in electrolysis cells to make pure copper. electrolysis is used to make copper pure.
what is the problem currently with mining copper
we are running out of copper rich ores
what are the 2 ways to class ores
- low-grade ores
- high-grade ores
what are the 2 ways to extract copper from low-grade ores
bioleaching and phytomining
how does Phytomining work
plants are grown in soil which contain low-grade copper ore. the plants absorb the copper ions. The plants are burnt and the copper is extracted from the copper compounds in the ashes. the copper ions are dissolved into sulfuric acid making copper sulfate. Displacement by Iron scraps and electrolysis makes pure iron.
how does bioleaching work
bacteria feed on the low-grade copper ore. through chemical and biological processes a solution of copper ions called a leachate is formed. The copper ion solution (leachate) is displaced by iron scraps and electrolysis is used to extract the copper from the leachate.
what is the disadvantage of bioleaching
the process is very slow. it can take years to just extract 50% of the ore.
what are the stages of a producst life cycle
1- raw material
2- manufacture
3- use
4- disposal
what is the first stage of completing a life cycle assesment of a product
if it is renewable, how the raw materials are extracted, do they need to be processed,
what is the second stage of completing a life cycle assessment of a product
are any pollutants formed like gas, does it require a lot of energy, are there any waste products and if fo how are they disposed of
what is the 3rd stage of completing a life cyce assessment of a product
how long can they product be used for, how many times can it be used over, does the usage of the product harm the environment
what is the 4th stage of completing a life cycle assessment of a product
how are the products disposed of, can they be recycled, how are the products transported
what is the 1st stage of a lifecycle assessment of a plastic bag
- made up of crude oil which is a finite resource
- ## crude oil is processed through fractional distillatin which requires alot of energy
what is the 2nd stage of the life cycle assesment of a plastic bag
- involves carcking and polymeristaion
- process rquires heating which uses a lot of energy
what is the 3rd stage of a life cycle assessment of plastic bag
- can be used multiple times
what is the 4th stage of a life cycle assessment of a plastic bag
- can be recycled
- if taken to a landfill it is not biodegradable and so takes up space in landfill and can be eaten by animals
- incenerating the products can release toxic gases into the atmosphere
what is the 1st stage of a lifecycle assessment of a paper bag
- obtained from trees but can be replanted
- habitats are destroyed when trees are cut down
- pollution is caused due to oil being used as fuel for transportation
what is the 2nd stage of a lifecycle assessment of a paper bag
- uses lots of water and some chemicals which could harm the environment
- transportation uses oil and so pollutes the air
what is the 3rd stage of a lifecycle assessment of a paper bag
- reusable butis mostly used only once
what is the 4th stage of a lifecycle assessment of using a paper bag
- can be recycled
- biodegradable
- non-toxic
what are the aims of the reduce, reuse and recycle campaigns
- reduce the use of limited resources
- reduce the use of our energy
- reduce the waste we produce
why is the recylcing aluminium important
- to protect the Earths’ reserve of aluminium
- getting aluminium requires the use of electrolysis which requires a lot of energy which is the recycling of aluminium is important as recycling saves energy (95% energy saved) and thus money as recycling does not require the use of electrolysis
how is aluminium recycled
1- aluminium is fed to a conveyer
2- aluminium is shredded
3- goes to the decoater
4- melted in furnaces
5- goes to tilting holding furnace
6- goes throught the filtration unit
7- becomes solidified in the direct chill casting unit
8- shredded again into ingots
how is recycling iron and steel sustainable
- tin cans and some car parts can get melted down and reformed to ingots
- this saves 50% of the energy
- 50% less pollutants are made by recycling iron rather than collecting iron as it uses 50% less fossil fuels
why is recycling copper harder than recycling other stuff
as copper is usually in mixed with other metals to form an alloy which means you have to seperate it the copper first then melt it down to form it to ingots. however copper wires are pure so they can be melted down straight away to be formed into ingots
how have humans impacted the natural cycling of nitrogen
- when plants grow they take in nitrogen in the soil and when they die they decompose allowing the nitrogen to go back into the soil however farmers collect the crops so the nitrogne can’t go back into the soil which is why farmers need to use fertillisers
what is the 1st step of the haber process
nitrogen gas is collected from the air through fractional distillation ( -200 degrees celcius is the temp required for nitrogen to be a liquid)
hydrogen is collected from reacting mthane and stem to form hydrogen and CO2
what is the 2nd stage of the haber process
the nitrogen and hydrogen are purified and passed over an iron catalyst and at high temperatures ( 400 degrees celcius) and high pressures ( 200 atmospheres). which gives the reversible reaction:
N2 + 3 H2 <—> 2 NH3
nitrogen + hydrogen <—> ammonia
what happens at equilibrium
the amount of products and reactants wont change
what is dynamic equilibrium
when the forward reaction = the backward reaction
in the haber process which reaction is endo and exothermic
forward reaction is exothermic and backward reaction is endothermic
how does temperature affect the haber process
lower temps means higher yield of ammonia but slower reaction
in the haber process which reaction produces more moles of gas
the forward reaction produces 2 moles of ammonia whil the backwards reaction produces 4 moles
how does pressure affect the haber process
high pressures would lead to a higher yield os ammonia but can be dangerous as hydrogen is explosive
why is an iron catalyst used in the haber process
to speed up the reaction (it does not effect the yield)
what is corrosion
a chemical reaction between the metal and the substances in the environment
what is the corrosion of iron called
rusting
what can corrosion do to a metal
- affect the strength
- affect the look
- or destroy the metal
why does aluminium not rust
most aluminium metals have a protective oxide layer which protects it from corrosion
how do you prevent rust
air and water is needed for iron to rust. which is why if your wrap/coat iron in oil, plastic or a less/mor reactive metal the iron will not rust
owhy is more reactive metals used to coat iron
as when the coating get scratched the iron does not rust
how is iron coated it a more reactive metal
the iron is galvanised which allows zinc to be coated in the iron
how does zinc stop rusting
zinc is more reactive than iron so it has a stronger tendancy to tun into positive ions by giving away electrons. as the zinc atoms lose electrons they become oxidised so any water or oxygen reacts with zinc rather than the iron. this is called sacrifical protection which sacrifices the zinc to save the iron
how can you setup a test to test that oxygen and water is needed for rusting
1- setup 3 test tubes
2- test tube A place calcium chloride chloride to remove any water then place some cotton wool and then the iron object.
3- test tube B place nail can cover with boiling water and then a layer of water
4- test tube c place nail and add some water ontop so that the tops of the nail is exposed to the air
what is copper made up of
copper and tin
why is bronze useful
it is highy resistant to corrosion
what is brass made up of
copper and zinc
why is brass useful
it is harder than copper and can be shaped into sheets to be used for musical instruments or taps
why are aluminium alloys good
it has a low density (cause of the aluminium) which makes it lightweight but really strong so it is used in aircraft
what is gold alloys normally made up of
gold ofc and copper when it’s used to make jewellary. gold purity is measured in carat (highest is 24 carat)
what is steel made up of and why is it useful
it is mde up of iron and carbon but other metals can also be added to have steel with different properties
what is the simplest form of steel
carbon steels
why is carbon steel used
it is the cheapes steel to make and by controlling the carbon content the steel can be made stronger if more carbon is added but it becomes more brittle. on the other hand lower carbon content means a softer steel but it is less brittle
what are the cons of using alloy steels
- more expensive
what are nickel steels used for
bicyle chains, long-span bridges and military armour plating as it is very resistant to stretching forces
what is tungsten steel used for
high speed tool bits as it spins very fast so it becomes hot and tungsten steel is very resistant to high temperatures
what is chromium-nickel steel used for
it is very hard and it is strong which makes it very useful but it does not rust which is why it is used for cooking utensils and cutlery
it is also used in chemical plants as it is used in reaction vessels which is why chemical plants are expensive to set up
