Using Earth’s resources Flashcards
What do we use resources for?
Warmth
Shelter
Food
Transport
How do we produce resources?
Agriculture
Tree planting
Synthetic resources
Examples of agriculture
Growing cotton from a plant
So we can grow as much as possible for the needs
Examples of tree planting for fuel
Woodchips act as biofuel to power power stations
Examples of synthetic resources
Natural rubber = tree sap
Synthetic rubber = crude oil
Finite
Resources that cannot be replaced as quickly as they are used
For example fossil fuels and metals
Renewable
Resources that will never run out as they can be replaced as quickly as we use them
For example wood
What does drinking water have to require?
Low levels of dissolved salts
Low levels of microbes like bacteria
Potable water
Water that is safe to drink
Pure water
Has no dissolved substances in it
Just H2O molecules
Are potable and pure water the same?
No because potable water contains small dissolved substances in small amounts
Whereas pure water is 100% H2O
How does the Uk get most of our potable water?
Rain water because it contains low levels of dissolved substances
Where does rain water accumulate?
Aquifers
Lakes
Rivers
Reservoirs
= supplies of freshwater
How to produce potable water?
Choose a freshwater supply eg lake
Pass it through filter beds to remove leaves and dirt
Sterilise water to kill bacteria using chlorine, ozone or UV light
How to produce potable water if it’s too salty?
Use desalination
Reduces levels of dissolved minerals to a good level
Desalination methods
Distillation
Reverse osmosis = pass it through membranes
Cons of desalination methods
Use large amounts of energy so it’s expensive
Uses of water
Drinking
Personal hygiene (bath, shower)
Flushing the toilet
Washing laundry
Farming
What does waste water contain and why do we need to treat waste water?
It contains:
Large amounts of organic molecules such as urine and feces
Harmful bacteria
Stages of treating waste water
Sewage passed through mesh (screened) to remove solids and grit
Settle in large sedimentation tanks
Produces a liquid effluent and a solid sludge
The sludge sinks and is taken away to be digested by anaerobic bacteria
Without oxygen, the bacteria produces biogas fuel
This digested sludge used as fertilisers
Where is sewage first passed through and why?
Mesh to be screened and remove solid particles and grit
What does the sewage settle in and why?
Large sedimentation tanks to separate into liquid effluent and solid sludge
What does sludge do?
Sinks then taken away to be digested by anaerobic bacteria
Which, with no oxygen the bacteria produces biogas for fuel
What is the digested sludge used for?
Fertilisers in farming
What happens to the liquid effluent and why?
Bubbles air into the liquid supplying it with oxygen
So aerobic bacteria can begin to multiply
And thus digest the harmful microorganisms
This is because we need to discharge it back into the sea but before had too much harmful microorganisms
What happens if the waste water is from industry and needs to be treated?
It will contain harmful chemicals so it will have to have these harmful chemicals removed first
Easiest way to produce potable water
Use ground water from aquifers
Because once treated with chlorine it’s safe to drink
Cons of aquifers
Can be polluted with fertilisers from farms
So you need to test the water carefully
Cons of Making potable water from treated waste water
Requires many steps so only done if water is scarce
Cons of Making potable water from salt water
Requires a lot of energy so it’s expensive
How are most metals on earth found?
Reacted with oxygen = metal oxide
Aka ores
Use of copper
In electronic equipment like phones
Metal ore
Contains enough metal in a rock to make it worth extracting
‘Economical’
Low grade ores
Rocks contain small amounts of the metal
Why are we mining low grade ores?
Because we are running out of higher grade metal ores
Phytomining
Growing plants on land that contain the metal compound we are extracting
Steps of phytomining
Plant absorbs metal compound in their tissue
Plants harvested and burnt
Ash contains high concentration of metal compound
Bioleaching
Using bacteria to extract metals
Steps of bioleaching
Bacteria mixes with low grade ore
Bacteria carries out chemical reaction and solution called leachate is produced
Leachate contains the metal compound we want
But what happens at the end of both phytomining and bioleaching?
Has left us with the metal compound
Which we need to extract the metal from
How can we extract the metal from the metal compound after bioleaching/ phytomining
Electrolysis
Displacement with a more reactive metal
Pros of phytomining + bioleaching
Allows us to economically extract metals from low grade ores
Methods do not involve transporting/digging large amounts of rock
Lifecycle assessment
Attempts to put a number/rating on the environmental impact of a product
Gives a rating at different stages of the products lifespan
Stages of a lifestyle assessment
Production
Transportation
Use
Disposal
Process of producing plastics
Use crude oil
Has to be extracted from oil refineries
These hydrocarbons must be separated then cracked
Then produce the polymer
Takes a lot of energy = use fossil fuels = climate change
Process of metal extraction (high grade ore)
Has to dig up ore then transport it to be processed
Extract the metal = toxic waste products
Plastic vs paper products
Plastic from crude oil = non renewable
Paper = renewable
Extracting crude oil = harmful in case of oil leak
Extracting wood = deforestation
Both need to be chemically processed = requires energy = release fossil fuels
Making paper requires water
Plastic is strong = reusable
Paper rips easily
Both have to be transported to be recycled/ landfill
Paper is heavier thus requires more energy
Plastic is not biodegradable
Paper is
Cons of life cycle assessment
We can measure waste products/ amount of energy
But we can’t be certain how damaging those are to the environmental
So we have to make estimates which may not be accurate
May be biased
Benefits of recycling
We can reuse resources
So we don’t have to extract more limited resources
Reduces waste = less harmful to environment
Methods of recycling
Reusing it
Crushing and melting it to a new product
How do we recycle metals?
Melt them then recast them into a new product
Problem with recycling metals
We have to separate them before melting it, depending on the product
Corrosion
Destruction of materials
Caused by chemical reactions the material has with substances in the environment
Rusting
A type of corrosion that ONLY applies to iron and alloys of iron
How to stop corrosion
Use a barrier between the material and environment
Such as grease or paint
Or coat it with metal (electroplating)
Galvanising
Electroplating
A means of protecting materials from corrosion
By coating it with a metal
Such as aluminium
Galvanising
Coating iron with zinc to protect it from rust
Acts as a barrier between material and environment
However if it gets scratched it still protects it as the oxygen reacts with the zinc since its more reactive
Sacrificial protection
Using a more reactive to protect a less reactive metal as a barrier in corrosion
Eg galvanising
Alloy
A mixture of metal and another element
Could be another metal or an element
What is the hardness of alloys like and why?
Harder than normal metals
Because it has different sized atoms
Which disrupts the layers and stops it from sliding over each other
Bronze
Alloy of copper and tin
Bronze properties
Extremely hard and doesn’t corrode easily
Bronze uses
Statues because it doesn’t corrode easily
Brass
Alloy of copper and zinc
Brass properties
Hard
But still malleable into different shapes
Brass used
Instruments
Door handles
Problem with gold
Used for jewellery but too soft
What is gold alloyed with to make it harder?
Silver
Copper
Zinc
Purity of gold in an alloy is measured in
Carats
24 carat gold = 100% pure gold
Steel
Alloy of iron, certain amounts of carbon and other metals
High carbon steel
Steel with a lot of carbon in it
Properties of high carbon steel
Extremely hard
Brittle (breaks easily)
High carbon uses
Cutting tools ie chisels
Low carbon steel
Steel with lower amounts of carbon
Properties of low carbon steel
Softer
Easily shaped
Low carbon steel uses
Car bodies
Problem with steel
Alloy of iron = prone to rust
How to fix problem with steel?
Make stainless steel containing chromium and nickel
So hard + resistant to corrosion
Aluminium alloys properties + uses
Low density = useful for aeroplane bodies
