C10 Flashcards
What do we use resources for
We use recourses to provide
-warmth
-food
-shelter
-transport
How are resources produced
-Agriculture (eg Cotton
-scientists have replaced natural recourses with synthetic alternatives
(Eg crude oil rubber)
What is a finite recourse
Recourses that cannot be replaced as quickly as they are being used,they will run out
(Eg fossil fuels)
What is a renewable recourse
Recluses we can replace as quickly as we use them(will not run out )
Why is it important that human activities are sustainable
We can meet our needs without preventing future generations from meeting theirs
How does chemistry play an important role in how we use recourses
-artificial recourses allow us to grow more food with the land available
-helps us provide safe drinking water
What do processes such as phto mining and bio leaching help us do
Help us extract metals more efficiently
What does drinking water have to have for it to be able to be drunk
-low levels of dissolved salts
-cannot have high levels of microbes
What is water that is safe to drink called
Potable water
What is pure water
-water which contains no dissolved substances
What is pure water
Water which contains no dissolved substances at all
In the uk what is our main source of potable water
Rain water(low levels of dissolved substances)
What are good sources of fresh water
Aquifers,lakes,rivers an in reservoirs.
How do we produce potable water
-choose a fresh water source
-pass water through filter beds
-water is sterilised
How is potable water produced from salt water
-desalination
What is desalination
-reduced the levels of dissolved minerals down to an acceptable level for potable water
What ways is desalination carried out
-reverse osmosis (passing through membrane)
-distillation
-reduce the levels of dissolved minerals
What is the issue with desalination
-requires a large amount of energy which makes them very expensive
what does waste water contain
-organic molecules
-harmful microorganisms
how is waste water treated
-the sewage is screened by passing through mesh (removing solids and grit)
-sewage settles in large sedimentation tanks
(this produces a liquid effluent and a semi solid sludge which sinks)
-sludge is taken away by anaerobic bacteria
-in absence of oxygen bacteria produces biogas
-digested sludge can be used for fertilisers
what does liquid effluent contain
contains large amounts of organic molecules and harmful microorganisms
how is the molecules and bacteria in liquid effluent reduced
-air is bubbled through the liquid effluent allowing aerobic bacteria to multiply
-in the presence of oxygen the aerobic bacteria digest the organic molecules and harmful microorganisms
-now the liquid effluent can be safely discharges into nearby rivers or into the sea
what is water used for
-industry
-personal hygiene
how is water that is used in industry be treated
-remove harmful chemicals
-enter general sewage treatment
what is the easiest way to produce potable water
-use ground waters from aquifers
-usually safe to drink once it has been treated with chlorine
what is a potential problem in water from aquifers
-sometimes can be polluted
-water has to be tested carefully
how is potable water made from waste water
-involves many purification steps
-only done is places where water in scarce
how is phytomining carried out
-plants grown on land containing metal compound
-plants aborn metal compound and concentrate it in their tissue
-plants are harvested and burned
-the ash contains a relatively high concentration of the metal compound
how is bioleaching carried out
-bacteria are mixed with low grade ore
-bacteria carry out chemical reactions and produce a solution called leachate
-leachate contains metal compound we want
at the end of both phytomining and bioleaching we need to extract the metal from the compound - how do we do this
we can displace the metal with a more reactive metal
-electrolysis
what do both phytomining and bioleaching allow us to do
-economically extract metals from low grade ores
-do not involve digging and transporting large amounts of rock unlike in traditional mining
what is a life cycle assessment
attempts to put a number on the environmental impact of a product
what is the stages of the life cycle assessment
-we need to asses the environmental impact of extracting and processing the raw materials
-asses the environmental impact of the product during its lifetime
-we need to asses the disposal of the product at the end of its useful life
how are polymers such as plastics produced
-using crude oil
-oil is extracted from the ground and then transported to oil refineries
-hydrocarbons have to be separated and then cracked
-the polymer has to be has to be produced
-all of these processes take a lot of energy,this leads to climate change
how does extracting metal require a lot of energy
-ore has to be dug out of the mine and transported for processing
-the metal has to be extracted from the ore producing large amounts of toxic waste products
what is the life cycle assessment like of a plastic shopping bag
-plastic bags are produced using chemicals from crude oil(non renewable)
-extracting crude oil can be harmful for environment, oil leak
-Crude Oil needs to be chemically processed, requiring large amount of energy and releases waste product
-plastic shopping bags are strong and are often reused as bin liners
-at the end of their life have to be transported to landfills
-plastic is non biodegradable and remain in the environment for a while
what is the life cycle assessment like of a paper shopping bag
-paper bags are made from wood from trees(renewable)
-felling trees for wood is extremely destructive towards habitats
-Woods need to be chemically processed, requiring large amount of energy and releases waste products
-paper shopping bags are not strong and tend to tear
-at the end of their life have to be transported for recycling
-paper breaks down quickly
what is the problem with the life cycle assessment
we cannot be certain of how damaging the waste products are to the environment
-this means in some cases we have to make estimates or value judgements which may not always be accurate
-life cycle assessments be biased
how are raw materials produced
-quarrying
-mining
how is quarrying harmful to the environment
produces large amounts of dust and destroys habitats
-takes a lot of energy to turn these raw materials into useful products
-this energy comes from limited resources
how is mining harmful to the environment
releases harmful chemicals into the environment
-takes a lot of energy to turn these raw materials into useful products
-this energy comes from limited resources
why is it important that we reduce our need for raw materials through reusing or recycling
-will help save limited resources and energy
-will reduce the amount of waste that we produce and have less harmful effect on the environment
how do we recycle metals
melt them and recast them into differnt products
what is the problems with recycling metals
-different metals usually have to be separated before being recycled
-however that depends on the properties of the final product
how is ground water treated
-filtered
-sterilized
how is sea water treated
-reverse osmosis
-distillation
