C12 Flashcards
Natural resources
Resources forming without human input, from the earth, sea or air
Examples of natural resources
Cotton for clothing or oil for fuel
How to replace natural products
Natural products can be replaced using synthetic products or improved upon by man-made processes
E.g. of natural products replaced by synthetic products or improved upon by man-made processes
Rubber is a natural product that can be extrafted from the sap of a tree, however man-made polymers have now been made which can replace rubber in uses like tires
How does agriculture help with natural resources?
Agriculture provides conditions where natural resources can be enhanced for our needs e.g. the development of fertilisers have meant we can produce a high yield of crops
Renewable resources
Renewable resources reform at a similar fate to, or faster than, we use them.
Examples of renewable resources
Trees
Fresh water
Food
Finite resources
Not formed quickly enough to be considered replaceable
Examples or finite resources
Fossil fuels
Nuclear fuels e.g. uranium and plutonium
Minerals and metals found in ores in the earth are also non-renewable materials
Copper
What happens after finite resources have been extracted?
Many finite resources undergo man-made processes to provide fuels and materials necessary for modern life e.g. fractional distillation is used to produce usable products such as petrol from crude oil and metal ores are reduced to produce a pure metal
Risks of extracting finite resources
People have to balance the social, economic and environmental effects of extracting finite resources. For example, mining metal ores is good because useful products are made, bit is bad for the environment as it uses loads of energy, scars the landscape, produces lots of waste and destroys habitats.
How is sustainable development inhibited
Using and extracting resources can he unsustainable due to the amount of energy used and waste produced. Processing the resources into useful materials, such as glass or bricks, can be unsustainable too, as the processes often use energy made from finite resources
Extracting copper from low-grade ores(new methods)
Bioleaching
Phytomining
Bioleaching
Bacteria is used to convert copper compounds in the ore into solible copper compounds, separating out the copper from the ore in the process. The leachate(the solution produced by the process) contains copper ions, whoch can be extracted by electrolysis or displacement eith a more reactive metal e.g. scrap iron.
Phytomining
This involves growing plants in soil that contains copper. The plants can’t use or get rid of the copper so it gradually builds up in the leaves. The plants can be harvested, dried and burned in a furnace. The ash contains soluble copper compounds from which copper can be extracted by electrolysis or displacement using scrap iron.
Disadvantages of traditional methods of copper mining
They’re pretty damaging to the environment.
Disadvantages of new methods of copper mining
They’re slow, but these new methods of extraction have a much smaller impact
Why is recycling metals important?
Recycling metals often use less energy than is needed to mine and extract new metal, conserves the finite amount of each metal in the earth and cuts down on the amount of waste getting sent to landfill.
There is also less acid rain(pollution) and less landfill creates local employment
How are metals recycled?
Metals are usually recycled by melting the, and then casting them into the shape of the new product.
What does the amount of separation required for recyclable metals depend on?
Depending on what the metal will be used for after recycling and the properties required of the final product, the amount of separation required for recyclable metals can change. For example, waste steel and iron can be kept together as they can both be added to iron in a blast furnace to reduce the amount of iron required to be extracted from the iron ore
Glass recycling
Glass recycling can help sustainability by reducing the amount of energy needed to make new glass products, and also the amount of waste created when used glass is thrown away
Methods of glass recycling
1) Glass bottles can be re-used without re-shaping.
2) Other forms of glass can’t be reused so they’re recycled instead. Usually the glass is separated by colour and chemical composition before being recycled.
3) The glass is crushed and then melted to be reshaped for use in glass products such as
bottles or jars. It might also be used for a different ourpose like insulating glass wool for wall insulation in homes.
Plastic bag
Raw materials - crude oil
Manufacturing and packaging - The compounds needed to make the plastic are extracted from crude oil by fractional distillation, followed by cracking and then polymerisation. Waste is reduced as the other fractions of crude oil have other uses.
Using the product - Can be reused. Can be used for other things as well as shopping
Product disposal- Recyclable but not biodegradable, and will take up space in oandfill and pollute land
Paper bags
Raw materials - Timber
Manufacturing and packaging - Pulped timber is processed using lots of energy. Lots of waste is made.
Using the product - Usually only used once.
Product disposal - Biodegradable, non-toxic and can be recycled
Life cycle assessments - what they show
Even though plastic bags aren’t biodegradable, they take less energy to make and have a longer lifespan than paper bags, so may be less harmful to the environment
Problems with life cycle assessments
Effect of some pollutants harder to give a numerical value to.
Producing an LCA isn’t an objective method - takes into account the values of the person carrying out the assessment.
Allocating numerical values to pollutant effects is less straightforward
Selective LCAs can be written to deliberately give positive advertising to the claims of a company.
Potable water
Water that’s been treated or is naturally safe for humans to drink
Potable water
Contains lots of other dissolved substances - pure water only contains H2O molecules.
The important thing is the levels of dissolved salts aren’t too high - it has a PH between 6.5 and 8.5 and also there aren’t any nasties swimming around
Fresh water
Water with not much dissolved in it
Fresh water sources
When it rains, water can either collect as surface water(in lakes, rivers and reservoirs) or as groundwater(in rocks called aquifers that trap water.
In the UK, the source of fresh water used depends on location. Surface water tends to dry up first, so in warm areas e.g. the south-east, most of the domestic warm supply comes from groundwater.
Processes for treating water from fresh water sources to be safe before it’s used
Filtration
Sterilisation
Filtration
A wire mesh screens out large twigs, and then gravel and sand beds filter out any other solid bits
Sterilisation
The water is sterilised to kill any harmful bacteria or microbes. This can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light.
How is potable water produced in dry countries?
Here, there’s not enough surface or groundwater, so seawater must be treated by desalination to provide potable water. Distillation can be used to desalinate seawater.
How to test and purify a sample of water in the lab using distillation:
3) Test the pH of the water using a pH meter. If the pH is too high or too low, you’ll need to neutralise it by adding some acid or alkali until the pH’s 7.
1) Accurately weigh an empty evaporating basin to two decimal places on the mass balance.
2) Add 25cm3 of water sample A into the evaporating balance.
4)Heat the evaporating basin on a tripod and gauze using a bunsen burner until solids start to form and the majority of water’s evaporated.
5)As the water in the flask heats up, it’ll evaporate and will enter the condenser as steam.
6)The drop in temperature inside the condenser, due to the cold water around it, will cause the steam to condense back into liquid water.
7) Collect the water running out of the condenser in a beaker.
8)Retest the pH of the water with a pH meter/universal indicator to check it’s neutral.
9) You can tell whether there were salts in the initial sample by looking to see whether there are any crystals in the round bottom flask once the water’s been distilled.
10) Weigh the cooled evaporating basin again and calculate the mass of solids dissolved in water.
Processes to treat seawater
Distillation
Reverse osmosis
How does reverse osmosis work?
The salty water is passed through a membrane that only allows water molecules to pass through, with ions and larger molecules trapped by the membrane so separated from the water.
Disadvantages of distillation and reverse osmosis
They both need lots of energy, so they’re really expensive and not practical for producing large quantities of fresh water
Sources from waste water
When flushing water we use down the train, it goes into the sewers and towards sewage treatment plants.
Agricultural systems also produce a lot of waste water including nutrient run-off from fields and slurry from animal farms.
Industrial processes also produce a lot of waste water that has to be collected and treated.
Why does industrial waste water need treatment?
As well as organic matter, it can also contain harmful chemicals, so has to undergo additional stages of treatment before it’s safe to release it i to the environment
Advantages and disadvantages of sewage treatment
Sewage treatment requires more processes than treating fresh water, but uses less energy than the desalination of salt water
Where do we get fertilisers from?
Air
What resources do we get clothes fibres from?
Plants/oil
What resources do we get building materials from?
Clay, limestone, trees
What resources do we get medicines from?
Oil/plants
What resources do we get polymers from?
Oil
Unsustainable development of metals
Throwing them away and making more from ores
Sustainable way of ensuring fuels for transport
Using biofuels
Unsustainable development(fuels for transport)
Fossil fuels
What can be quantified by life cycle assessments?
Energy, water, resource consumption and production of some wastes
Products that can be reused
Glass bottles - crushed and melted to make different glass products
Disadvantages of recycling
Collection problems
Transport problems/cost of transport
Difficult to separate metal from appliance/sort
Raw material making polyethene
Crude oil/petroleum
Why’s it more difficult to produce drinking water from waste water than from water in lakes?
Water needs more processes, because it contains more organic matter, microbes, toxic chemicals and detergents
How is copper ontained from solutions of copper compounds
By displacement using scrap iron or by electrolysis
Advantages of methods to extract metal from low grade ores
Need less energy than traditional methods
Can extract from low grade/concentration ores
Mining not required
Difficult to dispose of waste rock
Contaminated with toxic(metal compounds), bioleacher large amounts,98% of rock disposed as waste, takes up a lot of space
Is it economical to use scrap iron to get copper?
Iron is cheap
Iron is more abundant than copper
Advantage of phytoextraction
A high concentration of a metal can be obtained from a low grade ore
Advantage of phytomining(compared to traditional method)
Can release energy when plants are burned
Less expensive
Plants will remove carbon dioxide from the atmosphere as they grow
Disadvantage of phytomining compared to traditional metjod
Not continuous - long time for plants to grow
Supply not continuous - plants only harvested once/twice a year
Plastic bag raw materials
Crude oil
Paper bag raw materials
Timber
Plastic bag(manufacturing and packaging)
The compounds needed to make the plastic are extracted from crude oil by fractional distillation, followed by cracking and then polymerisation
Paper bag(manufacturing and packaging)
Pulped timber is processed using lots of energy, so lots of waste is made
Plastic bag(using product)
Can be reused
Used for other things as well as shopping
Paper bag(using product)
Only jsed once
Plastic bag product disposal
Recycle, but not biodegradable, will take up space in landfill + pollute land
Paper bag product disposal
Biodegradable, non-toxic and can be recycled
