P2 10 Global resources Flashcards
what humans use earth’s resources for
- oxygen in air
- food+water
- warmth
- shelter
- transport
define sustainable development
development which meets the needs of present generation without affecting the needs of future generations
role of chemistry in sustainable development (4 examples)
improve industrial processes:
* catalysts - speed up chemical reactions so less energy input required
* development of carbon nanotubes - strengthens materials, extends its life
improve agricultural processes:
* developing pesticides that break down - don’t enter food chains or pollute environment
* smart materials added to soil - able to retain water itself
define potable water
- water that is safe to drink
- contains a safe level of dissolved salts + microbes
- used for drinking/ washing/ cooking/ industrial processes
method of producing potable water from rain (UK) (3)
- water allowed to settle - large particles settle at bottom and water drawn out the top
- water passed through filter beds - removes small particles
- water is sterilised using chlorine/ozone/UV - kills most bacteria
method of producing potable water from seawater
desalination using simple distillation
1. mixture in flask heated until water boils and turns into vapour
2. vapour cools+ condenses in the condenser
3. pure water (distillate) is collected in a beaker, salt remains in flask
-> alternative method is reverse osmosis
problems with using distillation or reverse osmosis for desalination
requires large amounts of energy - expensive
steps for analysis of pH and dissolved solids in water samples (RP)
- place litmus paper in a drop of each sample and record pH
- measure the mass of a watch glass before+after placing a drop of each sample in it, then find the difference for the mass of dissolved solids
name sources of waste water (3)
- domestic: cleaning/washing, sewage, harmful bacteria+ organic matter
- agriculture: water used for irrigation contains pesticides/fertilisers
- industry: energy production/ manufacturing, organic matter, chemicals, oil
describe process of sewage treatment (4)
- screening: large sediment/grit removed by metal grid
- sedimentation: sediments allowed to settle to bottom forming sewage sludge, effluent floats to top
-
anaerobic digestion: sewage sludge is dried+ anaerobically digested by bacteria
-> bacteria produces methane during digestion, burned for energy - aerobic treatment: effluent drained into a tank, oxygen bubbled through so good bacteria break down harmful bacteria
- treated water released back into environment
problem of using waste water to produce potable water
uses a lot of resources/equipment for each stage
define life cycle assessment
- an assessment of a product’s environmental impact at every stage of its life
- helps identify areas which neg. impact environment and make changes to a product to make it more sustainable/ reduce carbon footprint
describe 4 stages assessed in a product’s life cycle assessment
- extraction/processing: finite/infinite source? damage to environment/pollution? energy needed to extract?
- manufacture+packaging: energy needed to make? harmful waste products produced/pollution? can packaging be recycled?
- usage: single-use or long-lasting? energy needed to operate?
- disposal: reusable/recyclable? sent to landfill? biodegradeable? energy used to incinerate? pollution?
++ conclusion - can be either pos or neg
cons of life cycle assessments (2)
- figures used to assess products are often biased - based on value judgements
- LCAs are sometimes misused - can be selective/shortened, eg. for advertising, to reach preferred conclusions and make a product appear more sustainable
carry out a life cycle assessment on bags made from paper vs plastic
- extraction/processing: paper made from sustainable trees but require a lot of energy to process, plastic made from crude oil which is finite
- manufacturing/packaging: plastic bags used less energy+water during manufacture
- usage: paper bags not strong/ long-lasting/ waterproof, plastic bags reusable for other purposes
- disposal: paper is biodegradeable+ recyclable, plastic not biodegradeable so go to landfill, can be recycled
- conclusion: plastic bags are more sustainable as they have a longer life and use less energy during manufacture
ways of reducing consumption of raw resources (4)
- recycling: requires less energy/pollution than extraction, eg. metal is melted to make new products
- reuse: eg. glass is crushed+melted to make new products
- repair: fix products rather than purchasing new ones
- reduce amount of resources used
define ore
a rock containing minerals from which metals are extracted for profit
name alternative methods of extracting metals (2) +why
- phytomining- extracting copper from soil by burning plants
- bioleaching- using bacteria to extract copper from copper compounds
-> doesn’t require digging/displacement of rock so more sustainable - no damage to landscape, doesn’t cause tremors
-> phytomining is carbon neutral - plants absorb CO2 when growing, then release when burned
describe process of phytomining
used to extract copper from copper compounds in soil
1. plants absorb copper ions from soil
2. plants containing copper are burned
3. copper is extracted from the ash using electrolysis or displacement with scrap iron
describe process of bioleaching
- bacteria absorbs copper compounds
- bacteria excrete a metal solution (leachate) containing copper compounds
- copper is extracted using electrolysis or displacement with scrap iron
