topic 10 - using resources Flashcards
Define finite resources
resources that cannot be replaced as quickly as they are being used
Describe what humans use Earth’s resources for
To provide warmth, shelter, food and transport
- in many cases, these resources are produced by agriculture
What are natural resources used for?
To provide food, timber, clothing and fuels
How does chemistry improve agricultural processes?
- in some cases, Chemistry has replaced natural resources with a synthetic alternative
-> one example is rubber. Natural rubber comes from the sap of a tree however synthetic rubber is produced using crude oil. Around two-thirds of the rubber used in the world is now synthetic
Define renewable resources
resources that will never run out
What is sustainable development?
development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
how does chemistry play an important role in improving agricultural and industrial processes?
- artificial fertilisers allow us to grow more food with the land available
- chemistry provides water that is safe to drink
- processes such as phytomining and bioleaching help us to extract metals more efficiently
What is potable water?
- Potable water is water that is safe for humans to drink
- drinking water has to have sufficiently low levels of dissolved salts and microbes
What is the difference between potable water and pure water?
Pure water only contains H2O molecules whereas potable water contains dissolved substances
What provides most of the UK’s potable water?
- in the UK, rain water provides most of our potable water. Rain water contains low levels of dissolved substances
How is most of the UK’s potable water produced?
- choosing an appropriate source of fresh water
- passing the water through filter beds
- sterilising
Describe the production of potable water
- pass fresh water through filter beds -> this is to remove materials such as leaves and suspended particles
- the water is then sterilised to kill microbes. In the UK we use chlorine to sterilise potable water, however, in some parts of the world, ozone or ultraviolet light is used instead
When is desalination required?
- if supplies of fresh water are limited, desalination of salty water or sea water may be required
what is desalination?
desalination reduces the levels of dissolved minerals down to an acceptable level for potable water
How is desalination carried out?
- Desalination can be done by distillation or by processes that use membranes such as reverse osmosis
- these processes require large amounts of energy
What is reverse osmosis?
- seawater is forced through a membrane at high pressure.
- The membrane allows water molecules to pass through but prevents any other chemicals dissolved in the water from passing through.
How is wastewater produced?
- Urban lifestyles and industrial processes produce large amounts of wastewater
- all of this wastewater contains a very large amount of organic molecules e.g. from urine and faeces
- they also contain harmful microbes such as bacteria
how is wastewater treated?
- sewage and agricultural wastewater require the removal of organic matter and harmful microbes
- industrial waste water may require removal of organic matter and harmful chemicals
how is wastewater treated?
- sewage and agricultural wastewater require the 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?
- In the first stage, the sewage is screened by passing through a mesh - this removes solids and pieces of grit
- Now the sewage can settle in large sedimentation tanks
- this produces a liquid effluent and a semi-solid sludge which sinks
- the sludge is taken away and digested by anaerobic bacteria
- in the absence of oxygen, these bacteria produce biogas which can be burned for electricity
- at the end, the digested sludge can be used as fertilisers for farming
- the liquid effluent contains large amounts of organic molecules and harmful microorganisms -> this needs to be reduced before returned to the environment
- air is bubbled through the liquid effluent. This allows aerobic bacteria to multiply
- In the presence of oxygen, the aerobic bacteria digest the organic molecules and harmful microorganisms
- After this stage, the liquid effluent can be safely discharged into nearby rivers or the sea
What is the easiest way to produce potable water?
- the easiest way to produce potable water is to use groundwater from aquifers
- usually, this is safe to drink once it has been treated with chlorine
- however, aquifers can sometimes be polluted so the water from aquifers needs to be tested carefully
Where are most metals found?
the Earth’s crust
What is the problem with copper?
- copper ores are becoming scarce
- this means that copper must be extracted from low-grade ores
What is the problem with copper?
- copper ores are becoming scarce
- this means that copper must be extracted from low-grade ores
What are low-grade ores?
- low grade ores contain only a very small amount of copper
What are the two methods used to economically extract copper from low-grade ores?
- phytomining
- bioleaching
what is the function of phytomining?
- phytomining uses plants to absorb metal compounds.
-The plants are harvested and then burned to produce ash that contains compounds
what is the function of bioleaching?
- bioleaching uses bacteria to produce leachate solutions that contain metal compounds
How do we extract copper from the compound?
- in the case of copper compounds, we can displace the copper using iron
- iron is more reactive than copper
- it is also cheaper to use scrap iron
- we can also extract the copper using electrolysis
what do new methods of mining avoid in terms of disadvantages of traditional mining?
- avoids disadvantage of traditional mining methods such as digging, moving and disposing large amounts of rocks
what are the stages for a life cycle assessment?
- 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
what is a life cycle assessment?
- assessments carried out to assess the enviornmental impact of products in different stages
what are some examples of raw materials?
- glass
- metal
- plastic
- clay ceramics
how are raw materials often obtained?
quarrying or mining
how are raw materials often obtained?
quarrying or mining
what are the disadvantages of quarrying?
- produces large amounts of dust
- destroys habitats
what are the disadvantages of mining?
- can release harmful chemicals into the environment
- it also takes a lot of energy to turn these raw materials into useful products -> this energy often comes from limited resources e.g. fossil fuels
Why is it important to try to reduce our need for raw materials?
- this will help to save limited resources and energy
- it will reduce the amount of waste that we produce and have a less harmful effect on the environment
what are the disadvantages of reducing the use of limited resources?
- materials need to be sorted before they can be recycled which also required energy and labour
- products made from recycled materials may not always be of the same quality as the original
what is a formulation?
a mixture of liquids that has been designed as a useful product
why do some water companies add fluoride to drinking water?
to improve dental health
what is chlorine at room temperature?
a gas
what is corrosion?
- the destruction of materials by chemical reactions with substances in the environment
what is an example of corrosion?
- rusting
what does rusting only apply to?
- rusting only applies to iron and to alloys of iron such as steel
how do you carry out an experiment on the conditions of rusting?
- in the first test tube- iron nail in distilled water and the test tube is open to the air
- in the second test tube- an iron nail and this is also in distilled water - however, this water has been boiled. Boiling water removed any dissolved air
- the water has then been covered with oil. this prevents any air in the test tube from dissolving in the water
- in the third test tube we have anhydrous calcium chloride powder. This removes any water from the air in the test tube
- we have also placed a rubber bung on the test tube. This prevents any moist air from entering
- leave for several days for results
- in test tube 1, we find that the iron nail is covered in rust
- in test tubes 2 and 3 there’s no rust
- this tells us that rusting requires both air and water
how can corrosion be prevented?
- corrosion can be prevented by applying a coating that acts as a barrier, such as greasing, painting or electroplating.
- these methods stop the air or water from coming into contact with the metal
why are materials made from aluminium protected from corrosion?
- materials made from aluminium form an oxide layer which acts as a protective layer preventing further corrosion
what is an alloy?
a mixture of metals
why do alloys tend to be harder than pure metals?
- the atoms in an alloy are of different sizes
- this disrupts the layers and stops them from sliding
- this means that alloys are generally harder than pure metals
what is bronze an alloy of?
copper and tin
what is brass an alloy of?
copper and zinc
what is a use of gold alloys?
jewellery
what is the purity of gold measured in?
carats
what is steel an alloy of?
iron, carbon and other metals
what are two properties of high-carbon steel?
- hard
- brittle
what are the two properties of low-carbon steel?
- soft
- easily shaped
what are 2 properties of stainless steel containing chromium and nickel?
- hard
- resistant to corrosion
what is a property of alloys containing aluminium?
low density
what is a use of alloys containing aluminium?
- body of aeroplanes
how do you make soda lime glass?
- by heating a mixture of sand, sodium carbonate and limestone
how is borosilicate glass made?
- by melting a mixture of sand and boron trioxide
how are ceramics made?
shaping wet clay and heating in a furnace
what are 3 properties of ceramics?
- hard
- resistant to chemical attack
- brittle
what are composites?
- they are made up of 2 materials producing a product with improved properties for a particular use
what are the 2 materials that make up composites?
- matrix/binder
- reinforcement (surrounded by the matrix)
what are the features of a carbon fibre composite?
- the reinforcement material are fibres of carbon and the matrix is a plastic resin
- carbon fibre composite is very strong and light. this makes it extremely useful e.g. in cars
what defines the properties of polymers?
- the type of monomers
- the conditions used to carry out the polymer
what are the two types of poly(ethene)?
- LD poly(ethene)
- HD poly(ethene)
how is low-density polyethene produced?
under high pressure
what are 2 uses of LDPEs?
- carrier bags
- bubble wrap
how is high density polyethene produced?
- 50°C
- catalyst
how do the structures of LDPE and HDPE differ?
- LDPEs contain branched polymer chains
- whereas HDPEs contain polymer chains that are closely packed together
what are 2 uses of HDPEs?
- plastic bottles
- pipes
what happens when thermosoftening and thermosetting polymers are heated?
- thermosoftening polymers melt when heated
- thermosetting polymers do not
why do thermosoftening polymers melt when heated?
- they have weak intermolecular forces between the polymer chains which require little energy to overcome
why do thermosetting polymers not melt when heated?
- they have strong covalent bonds between chains which are not easily overcome
what is a use of manufacturing ammonia using the Haber process?
to make nitrogen-based fertilisers for farming
what is the word equation for the Haber Process?
nitrogen + hydrogen ⇌ ammonia
what are the raw materials for the Haber process?
- nitrogen
- hydrogen
what can nitrogen be extracted from?
air
what can hydrogen be extracted from?
natural gas
what are the conditions for the Haber process?
- 450°C
- 200 atm
- iron catalyst
how do you increase the yield of the Haber process?
- cool the ammonia to turn it into a liquid which is removed
- we can then recycle the unreacted nitrogen and hydrogen back over the catalyst
what happens to the gases in the cooling chamber? (Haber process)
- gases are cooled
- ammonia condenses into a liquid
- the unused nitrogen and hydrogen are recycled and returned back into the reactor
what are 2 reasons why fertilisers are used when growing crops?
- increase crop yield
- increase rate of growth
what are the 3 essential elements found in fertilisers?
- nitrogen
- phosphorus
- potassium
what can ammonia be used to manufacture?
ammonium salts and nitric acid
how are potassium chloride, potassium sulfate and phosphate rock obtained?
from mining
what is phosphate rock treated with to produce soluble salts which can then be used as a fertiliser?
nitric acid or sulfuric acid
what is produced when nitric acid reacts with phosphate rock?
phosphoric acid
what is produced when sulphuric acid reacts with phosphate rock?
single superphosphate
what is produced when phosphoric acid reacts with phosphate rock?
triple superphosphate
