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