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