C14 - The Earth's Resources 2️⃣✅ Flashcards
What is a finite resource?
Resources that are being used up faster than they can be replaced.
What is a renewable resource?
Resources that be renewed at the same rate at which they are used up
Give 2 examples of finite resources which are processed to either give energy or materials
ENERGY: crude oil processed to produce fuel for multiple different methods of transport
MATERIALS: crude oil is processed to produced plastics for clothing or sheets
Give 2 examples of renewable resources which humans supplement by agriculture
- wood/ timber
- clothing/ leather/ cows
Give 2 examples of synthetic products which can be used instead of natural resources?
- Cotton - clothing —> polyester
- wood - material —> PVC
What are synthetic products and why are they used instead of natural rescources?
Synthetic products are when it is not made up of natural substances, like cotton or wool, and is man-made artificially from chemical reactions
What is potable water?
Water that is safe to drink with low levels of dissolved salts and microbes
What is pure water?
That is pure H20, just one molocule, no other substances in it
Why is potable water not pure water?
Because, even though it contains low levels, it still contains levels of dissolved substances, so its not 100% H20
How can we collect fresh water in the uk?
rainwater contains low levels or dissolved substances and can be found and obtained underground, in lakes or in rivers
How do we produce potable water in the uk?
- sedimentation - solids in water sink to bottom of tank and are removed
- filtration - fine particles like sand are removed via filterbeds
- sterilisation - mircobes left in water are killed using sterilisng agents
What 3 sterilising agents are used in the treatment of fresh water?
- Chlorine
- Ozone
- Ultraviolet (UV) light
What is the best sterilising angent and why?
UV light is the best as it leaves nothing in the water after its used whereas ozone and chlorine still leave small ammounts in the water
What are 2 alternate methods of obtaining potable water if large ammounts of fresh water arent avainable?
- Disitllation
- Reverse Osmosis
How do you obtain potable water without fresh water?
Desalination of sea water
How does distillation work?
By a liquid (sea water) being heated to boiling point in order to vaporize it, then condensed back into a liquid so that it is separated from impurities (e.g. salt)
How does reverse osmosis work?
Where 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
What is a negative to desanlination?
Both methods are very expensive and require lots of energy
What are the 4 steps to treating waste water?
- Screening and grit removal
- Sedimentation
- Anaerobic digestion of sewage sludge
- Aerobic biological treatment of effluent (liquid waste)
(Treating waste water)
How does screening work?
Large solid particles are removed (e.g. grit) by passing the sewage through a fine screen
(Treating waste water)
How does sedimentation work?
Sedimentation allows the smaller solid particles (sediment) to settle at the bottom of the tank forming sewage sludge while the liquid effluent remains above
(Treating waste water)
How does Anaerobic digestion of sewagte sludge work?
The sewage sludge is dried and anerobically digested (broken down by microorganisms in the absence of oxygen) therefore removing organic matter amd also producing biogas for electricity
(Treating waste water)
How does aerobic biologucal treatment of effluent work?
The effluent is aerobically digested (broken down by microorganisms in the presence of oxygen). Removing any remaining organic matter and harmful microbes
How is it ensured that effluent is rid of any remaining organic matter or harmful microbes?
Lots of 02 is bubbled into the water to make sure its digested aerobically (with oxygen)
What are the 3 main methods to obtain potable water?
- Treatment of fresh water
- Desalination of salty/ sea water
- Treatment of waste water
Rank the 3 main methods for obtaining potable water from best to worst
- Treatment of fresh water - requires little to no energy and minimal equipment
- Treatment of waste water - requires more equipment but less energy
- Desalination - requires lots of energy and specialist equipment
What are Life Cycle Assessments (LCAs)?
An assessment carried out to assess the environmental impact of prodcuts at each stage of its ‘life’
What are the 5 things assessed in a LCA?
- Extrating and processing of raw materials
- Manufacturing and packaging
- Use and if it can be reused
- Disposal and the end of its useful life
- Transportation and distributuion at each stage
What metals can be extracted by the reduction of carbon?
- Zinc
- Iron
- Copper
How is carbon displacement/ reduction used to extract metals?
Carbon atoms displace the metals and take the oxygen from the metal oxide to form carbon dioxide, leaving behind a pure metal
Why can we only extract zinc, iron and copper using carbon?
Because they are less reactive than carbon so it will displace them
What metals can be extracted using electrolysis?
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
What is phytomining?
Using plants to absorb and therefore extract metal compounds
How does phytomining work?
- Plants are grown on a low-grade ore
- Plants absorb the metal ions through there roots
- Plants are then harvested and burnt
- The ash left behind contains a higher concetration of metal than the original ore
- Ash is then processed to obtain the metal
What is bioleaching?
Using bacteria to produce leachate solutions that contain metal compounds
How does bioleaching work?
Certain bacteria can break down low-grade ores to produce an acidic solution containing copper ions. This solution is called a leachate and can be separated using electrolysis or displacement reactions to form a pure metal.
What are 2 biological methods of metal extraction?
Bioleaching & Phytomining
What is the positive and negatives to phytomining?
- Its slow
- requires high temperatures
- But conserves supplies of finite ores
- Reduces rock waste that has to be disposed of
What is the positive and negatives to bioleaching?
- doesnt require high temperatures
- But produces toxic substances including sulfuric acid which can damage the environment
What is an ore?
Ores are naturally occurring rocks that contain metals or metal compounds
What is desalination?
Desalination is the process by which the dissolved mineral salts in water are removed
