C14 The Earth's Resources Flashcards
What is the difference between potable and pure water?
Pure water contains no dissolved substances
What are the 2 main steps to produce drinking water from lakes?
Filtration - Removes large solids
Sterilisation - Remove microbes
Describe the steps to produce potable water
- WATER COMES FROM A FRESH SOURCE (River, lake or reservoir)
- Water is passed through a filter made of fine sand and gravel, removing any
remaining particles of mud or grit, so the water is clean. - Water is passed through another filter, made with metal bar close together,
to catch large objects such as leaves and twigs - Water reaches a settlement tank, where sand and soil settle out
- Aluminium sulfate and lime are added to the water, small particles of dirt
clump together and sink to the bottom of the water - Chlorine added to kill bacteria (Or Ozone or UV light)
- pH of water checked to be neutral + sludge dumped in landfill
What is required to produce potable water?
A fresh water source e.g. a river, lake or reservoir
What method is used to produce potable water from salty water?
Desalination (Reducing amount of dissolved minerals in water)
Describe two methods of desalination
- Distillation
- Passing the water through a membrane (Reverse osmosis)
What is a disadvantage to methods of desalination?
They require a lot of energy, and are therefore expensive
What does it mean if a resource is finite?
It can’t be replaced as quickly as it’s being used
Name 2 finite resources
Metals and Fossil fuels
What do we use resources to provide?
Warmth, Shelter, Food and Transport
Describe a resource that is produced from farming
Cotton - Produced from a plant
Timber/ Fuel - Produced from trees
Describe a natural resource that has been replaced with a synthetic alternative
Rubber - Natural rubber comes from the sap of a tree, however synthetic rubber is produced using crude oil
Describe how waste water is treated
- Sewage passes through a mesh, removing solids and grit
- Sewage settles in sedimentation tank, producing a liquid effluent and
sludge, which is taken away and digested by anaerobic bacteria - Digested sludge can be used as fertiliser for farming
- Air is bubbled through the water to increase digestion from aerobic bacteria
Why is anaerobic bacteria used to digest waste sludge in wotar?
It produced biogas, which can be burnt to produce energy
Why is air bubbled through the water during waste treatment?
It allows aerobic bacteria to multiply, which digest harmful organic molecules and microorganisms
Describe the easiest to hardest ways of producing potable water
- Ground water from aquifers (usually safe once treated with CL)
- From waste water (Takes many purification steps)
- From salt water (Requires a lot of energy and is expensive)
What is one risk associated with extracting water from aquifers?
They may be polluted e.g. with fertilisers from farms
How are raw materials usually obtained?
Quarrying or mining
Describe the disadvantages of quarrying and mining
Quarrying - Produced large amounts of dust and destroys habitats
Mining - Releases harmful chemicals into the environment
(Also requires a lot of energy which comes from fossil fuels)
Describe how glass bottles can be reused
They can be crushed and melted to form new products
How are metals recycled?
Give a disadvantage
By being melted and recasted into new products
Different metals need to be separated before being recycled
Describe how plastics can be recycled?
They can be recycled to make fleece jackets and carpets
Describe an LCA for a plastic bag and a paper bag
PLASTIC
- Produced using chemicals from crude oil (finite resource)
- Extracting crude oil can be harmful to habitats (releasing chemicals)
- Oil must be chemically processed (requires energy + releases waste)
- Plastic bags are strong and can be reused
- Must be transported (for recycling or landfill) which requires energy
- Plastic is NON BIODEGRADABLE, and remain in the environment for a long
time
PAPER
- Produced using trees, which are a renewable resource
- Cutting down trees is extremely disruptive to habitats e.g. forests
- Wood must also be chemically process
- Making paper also requires a large amount of water
- Paper bags aren’t as strong and tend to tear (Only used once)
- Paper bags are often heavier than plastic bags (more energy to transport)
- Paper breaks down quickly, especially when wet
Plastic is non biodegradable, what does this mean?
It isn’t broken down by microorganisms
What is an issue with LCA’s?
We cannot be certain how damaging each product is to the environment, so in some cases, some estimates/ value judgements must be made, and may not always be accurate
Also they could be biased to support claims made by advertisers
Seawater is forced though a membrane to produce freshwater, suggest why water molecules can pass through the membrane but not sodium or chlorine ions
- Water molecules have no overall charge
- Na+ and Cl- ions are larger
Suggest 3 reasons why copper shouldn’t be disposed of in landfill sites
- Copper can be recycled/reused
- Copper compounds are toxic
- Copper is running out
- Copper is expensive
- Landfill sites are filling up
Suggest 3 reasons why world production of coal is predicted to increase
- Plentiful supply
- Easier to extract
- Oil/gas is running out
(Oil is a limited resource)
What is in water filters that removes hardness from water?
Ion exchange resin
Suggest why water filters in homes contain particles of silver
Prevents growth of microbes
Describe how phytomining can be used to extract copper
- Plants grown on land containing desired compound
- Plants absorb metal (copper) compound and concentrate it in its tissue
- Plants are harvested and burnt
- Ash contains relatively high concentration of metal compound
(extract with iron or electrolysis)
Describe how bioleaching can be used to extract copper
- Bacteria is mixed with low grade ore
- Bacteria carry out chemical reactions and produce a solution called a LEACHATE
- Leachate contains desired metal compound
- Extract copper from metal compound using displacement with iron
(iron is cheap)
What are the benefits of alternate methods of extracting metals?
- Don’t involve digging/quarrying etc
- Help to economically extract low grade ores
