Topic 10 - Using Resources Flashcards
What do humans use the earths resources for?
Warmth, shelter, food, transport
What do natural resources supplemented by agriculture provide?
Food, timber, clothing, fuels
What are processed to provide energy and materials?
Finite resources from the Earth, oceans and atmosphere
What does chemistry play an important role in?
- Improving agricultural and industrial processes to provide new products
- Sustainable development
What is the sustainable development?
Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
Give an example of natural products that are supplemented or replaced by agricultural and synthetic products?
Rubber is a natural product that can be extracted from the sap of a tree, however man-made polymers have now been made which can replace rubber in uses such as tires
What substance is essential for life?
Water of appropriate quality
What should drinking water consist of for humans?
Drinking water should have sufficiently low levels of dissolved salts and microbes
Define potable water?
Water that is safe to drink
What is potable water?
Not pure water in the chemical sense but it contains dissolved substances
What do the methods used to produce potable water depend on?
Available supplies of water and local conditions
In the UK what does rain provide?
Water with low levels of dissolved substances (fresh water) that collects in the ground, lakes and rivers
What are the three methods of producing portable water?
- choosing appropriate source of fresh water
- passing the water through filter beds
- sterilising
Give examples of sterilising agents used for potable water?
Chlorine, Ozone, ultraviolet light
What happens if suppliers of freshwater are limited?
Desalination of salty water or sea water may be required
How can desalination be done?
By distillation or by processes that use membranes such as reverse osmosis
What do the processes of desalination require?
Large amounts of energy
When it rains how does water collect?
- surface water (lakes, rivers and reservoirs)
- groundwater (in rocks called aquifers the trap water underground)
What are the disadvantages of desalination processes?
Require loads of energy so they’re expensive and impractical for producing large quantities
Where are large amounts of waste water produced?
Urban lifestyles and industrial processes
What does waste water required?
Treatment before being released into the environment
What treatment does sewage and agricultural waste water required?
Removal of organic matter and harmful microbes
What treatment does industrial waste water require?
Removal of organic matter and harmful chemicals
What are the four stages of sewage treatment?
- screening and grit removal
- sedimentation to produce sewage sludge and effluent
- anaerobic digestion of sewage sludge
- aerobic biological treatment of effluent
Describe stage one of sewage treatment?
The sewage is screened which involves removing any large bits of material as well as any grit
Describe stage two of sewage treatment?
The sewage then stands in a settlement tank and undergoes sedimentation
What is sedimentation of sewage?
The heavier suspended solids sink to the bottom to produce sludge while the lighter effluent floats to the top
What is stage three of sewage treatment?
The sludge is removed and transferred into large tanks where it gets broken down by bacteria in anaerobic digestions
What is biological aerobic digestions of sewage?
Air is pumped through the water to encourage aerobic bacteria to break down any organic matter and other microbes in the water
What is anaerobic digestion of sewage?
Organic matter is broken down and releases methane gas which can be used as an energy source, and the remaining digested waste can be used as a fertiliser
What is stage four of sewage treatment?
The effluent in the settlement tank is removed and treated by biological aerobic digestions
What additional stages may be added for waste water containing toxic substances?
Adding chemicals, UV radiation or using membranes
Compare the process of treating freshwater to treating sewage?
Sewage treatment requires more processes and treating freshwater but uses less energy than the desalination of salt water so can be used as an alternative in areas where there is not much freshwater
What is the disadvantage of using sewage as alternative in areas where there is not much fresh water?
Some people don’t like the idea of drinking water that used to be sewage
What is the problem with the earths resources of metal ores?
They’re limited
What are new ways of extracting copper from low-grade ores?
Phytomining and bioleaching
Why do we need new ways of extracting copper?
Copper ores are becoming scarce
What do The new ways of extracting copper avoid?
Traditional mining methods of digging, moving and disposing of large amounts of rock
What is phytomining?
Using plants to absorb metal compounds
how does phytomining work?
The plants are harvested and then buried to produce ash that contains metal compounds
What is bioleaching?
Using bacteria to produce leachate solutions that contain metal compounds
What are the metal compounds processed for?
To obtain the metal
Give an example of a metal compound that can be processed to obtain the metal?
Copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis
Why are life-cycle assessments carried out?
To assess the environmental impact of products in different stages
What are the environmental impacts assessed in life-cycle assessments?
- 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)
Why are extracting and processing raw materials assessed in lifecycle assessments?
It can damage the local environment (E.G.mining) and result in pollution due to the amount of energy needed to process and extract
Why is manufacturing and packaging assessed in a life-cycle assessment?
It can use a lot of energy resources and cause a lot of pollution (E.G.harmful fuels) and produce waste products which need to be disposed of
Why is using the product assessed in a life-cycle assessment?
It can damage the environment (E.G.burning fuels releases greenhouse gases and fertilisers can leach into streams causing damage to ecosystems) and how long it is used for can mean less waste in the long run
Why is product disposal assessed in life-cycle assessments?
Landfill sites take up space and produce land and water, energy is used to transport waste which causes pollutants to the atmosphere, products may be incinerated which causes air-pollution
Give examples of things that can be fairly easily quantified?
Use of water, resources, energy sources and production of some wastes
Why are life-cycle settlements not a purely objective process?
Because allocating numerical values to pollutant effects is less straightforward and requires value judgements
What can selective or abbreviated life-cycle assessments be devised to do?
Evaluate the product
What is the disadvantage of selective or abbreviated life-cycle assessments?
They can be misused to reach predetermined conclusions for example in support of claims for advertising purposes
What are selective life-cycle assessments?
Only shows some of the impacts of a product on the environment and can be biased
Compare the raw materials used for plastic and paper bags?
Plastic bags are made from crude oil and paper bags are made from timber
Compare the manufacturing and packaging for plastic and paper bags?
- Compounds for plastics are extracted from crude oil by fractional distillation, cracking and polymerisation, but waste is reduced as other fractions have different uses
- Pulped timber requires lots of energy and creates lots of waste
Compare the use of plastic bags and paper bags?
Plastic bags can be reused and used for other things where as paper bags are usually only used once
Compare the product disposal for plastic and paper bags?
- Plastic bags are recyclable but not biodegradable and will pollute land in landfill
- Paper bags are biodegradable, non-toxic and can be recycled
What does the reduction in use, reuse and recycling of materials by end users reduce?
- reduces use of limited resources
- reduces use of energy sources
- reduces waste
- reduces environmental impacts
Give examples of materials produced from limited raw materials?
Metals, glass, building materials, clay ceramics, most plastics
What does most of the energy for the processes of making materials come from?
Limited resources
What does obtaining raw materials from the Earth by quarrying and mining cause?
Environmental impacts
Give an example of a product that can be reused?
Glass bottles
How are glass bottles reused?
They can be crushed and melted to make different glass products
What happens if a product cannot be reused?
They can be recycled for different use
How are metals recycled?
By melting and re-casting or reforming into different products
What does the amount of separation required for recycling depend on?
The material and the properties required of the final product
Give an example for reducing the materials needed to recycle a metal?
Scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from an iron ore
What is corrosion?
The destruction of metals by chemical reactions with substances in the environment
Give an example of corrosion
Rusting
What substances in the environment are necessary for iron to rust?
Air and water
How can we prevent corrosion?
Applying a coating that acts as a barrier
What are the different ways that we can apply a coating to prevent corrosion?
Greasing, painting or electroplating
How is aluminium protected from further corrosion?
It has an oxide coating
Why is zinc used to galvanise iron?
The coating is reactive and contains a more reactive metal (zinc) which provides sacrificial protection
Why is the sacrificial method used?
Because water and oxygen will then react with the sacrificial metal instead of the metal that needs protection
What are most metals in every day use?
Alloys
What is bronze?
An alloy of copper and tin
What is brass?
An alloy of copper and zinc
What is gold used as jewellery?
An alloy with silver, copper and zinc
What is the proportion of gold in the alloy measured in?
Carats
What are the different carats?
24 carat = 100%
18 carat = 75%
What are steels?
Alloys of iron that contain specific amounts of carbon and other metals
Describe high carbon steel.
Strong but brittle
Describe low carbon steel.
Softer and more malleable
What are steels that contain chromium and nickel?
Stainless steels that are hard and resistant to corrosion
Describe aluminium alloys?
Low density
Give a use of bronze
Medals, decorative ornaments and statues
Give uses of brass
Water taps and door fitting
Give uses of gold
Jewellery
Give uses of aluminium alloys
Aeroplanes
Give a use of low carbon steel
Car bodies
Give a use of high carbon steel?
Bridges
Give a use of stainless steel
Cutlery
How is most of the glass we use made?
From soda lime glass that is made by heating a mixture of sand, sodium carbonate and limestone
How is Borosilicate glass made?
From sand and boron trioxide melted at higher temperatures than soda lime glass
Give examples of clay ceramics and how they are made?
Pottery and bricks – made by shaping wet clay and heating in a furnace
What do the properties of polymers depend on?
What monomers they are made from and the conditions under which they were made
What are low-density and a high density poly(ethene) produced from?
Ethene
What happens to Thermosoftening polymers when they are heated?
They melt
What happens to thermosetting polymers when they are heated?
They do not melt
How is low density poly(ethene) made?
Made from ethene at a moderate temperature under a high-pressure with a catalyst
Give a use of low density poly(ethene)
Bags and bottles
How is high density poly(ethene) made?
Made from ethene but at a low temperature and low pressure with a different catalyst
Give a use of high density poly(ethene)
Water tanks and drainpipes
Describe Thermo softening polymers
Contain individual polymer chains entwined together with weak forces between the chains, which can be melted and remoulded
Describe thermosetting polymers
Contain monomers that can form cross links between the polymer chains holding the chains together in a solid structure
What are most composite made from?
A matrix and reinforcement
What is a reinforcement?
Fibres or fragments of a material
What is the matrix?
Acts as a binder
Give examples of composite’s
- fibreglass
- carbon fibre
- concrete
- wood
Describe fibreglass
Consists of fibres of glass embedded in a matrix made of polymer which has a low density but is very strong and used for skis, boats and surfboards
Describe carbon fibre
Have a polymer matrix and a reinforcement made from long chains of carbon atoms bonded together or carbon nanotubes that are very strong and light so are used in aerospace and sports cars
Describe concrete
Made from aggregate (sand and gravel) embedded in cement which is very strong so used as a building material
Describe wood
A natural composite of cellulose fibres held together by an organic polymer matrix
What is the haber process?
It is used to manufacture ammonia
What can ammonia be used for?
To produce nitrogen-based fertilisers
What are the raw materials involved in the haber process?
Nitrogen from air and hydrogen from methane
Describe the haber process?
The purified gases are passed over a catalyst of iron at a high temperature (450°C) and a high-pressure (200 atm³)
What happens in the haber process?
Some of the hydrogen and nitrogen reacts to form ammonia, the reaction is reversible so some of the ammonia breaks down into nitrogen and hydrogen
What happens when the reversible reaction from the haber
process is cooled?
The ammonia liquefies and is removed and the remaining hydrogen and nitrogen are recycled
What factors affect the cost of making ammonia?
- cost of electricity and gas (continuous process)
- cost of wages (night workers)
- rate at which ammonia is made
- cost of reactants
- cost of equipment (needs to be high pressure)
- pressure (more dangerous, can explode)
- high temperature (expensive)
- catalyst (specific one, expensive)
Summarise the conditions for the haber process.
- low temperature increases percentage yield but is too slow
- High temperature increases rate of reaction but decreases percentage yield
- High pressure increases percentage yield but is expensive
What happens to the equilibrium when you increase temperature?
Equilibrium shifts to the endothermic side
What happens to the equilibrium when you decrease temperature?
Equilibrium shifts to the exothermic side
What happens to the equilibrium when you increase pressure?
Equilibrium shifts to side with fewer moles
What happens to the equilibrium when you decrease pressure?
Equilibrium shifts to the side with more moles
What happens to the equilibrium when you increase the concentration of the reactants?
Equilibrium will shift to the right hand side creating more product and a higher percentage yield
What happens to the equilibrium when you decrease the concentration of the reactants?
Equilibrium will shift to the left Arnside creating more reactants and a lower percentage yield
What happens to the equilibrium when you add more acid?
The concentration of H+ ions has increased so the equilibrium will shift to the left hand side
What happens to the equilibrium when you add more alkali?
The concentration on OH- ions increases and the equilibrium will shift to the right hand side as the OH- reacts with the H+ to form H2O and removes the H+ ions
Which compounds are used as fertilisers?
Compounds of nitrogen, phosphorus and potassium
What are fertiliser used for?
To improve agricultural productivity
What do NPK fertilisers contain?
Compounds of all three elements
How can industrial production of NPK fertilisers be achieved?
By using raw materials in several integrated processes
What are NPK fertilisers?
Formulations of various salts containing appropriate percentages of the elements
What can ammonia be used to manufacture?
Ammonium salts and nitric acid
Which materials used for fertilisers are obtained by mining?
Potassium chloride, potassium sulphate and phosphate rock
Can phosphate rock be directly used as a fertiliser?
No
How is phosphate rock used as fertiliser?
Phosphate rock is treated with nitric acid or sulphuric acid to produce soluble salts that can be used as fertilisers
What salt is produced when phosphate group is treated with nitric acid?
Calcium nitrate
What salt is formed when phosphate rock is treated with sulphuric acid?
Calcium phosphate + calcium sulphate
What salt is produced when phosphate rock is treated with Phosphoric acid?
Calcium phosphate
