Earths resources

• Define potable water


  water safe for human consumption that is not chemically pure
• State some sources of potable water

  -fresh water (easiest source, only needs filtering and sterilising)

  -sea water (most expensive, desalination is needed)

  -waster water ( less energy is used)
• Define the two desalination processes

  -distillation : boiling sea water, steam forms, condenses, leaving salt behind giving pure water

  -reverse osmosis : seawater getting passed through a semi permeable membrane that only allows water molecules through ( high amounts of energy needed for push force - expensive )
• Define the two natural resources

  -Renewable : regenerated at about/faster rate than they are being used

  -Non-renewable : regenerated at a much slower rate than they are being used
• What are some supplements to natural resources?

  Sythetic products such as polymers to repalce rubbers
• What are the three sources of waste water?

  -Domestic = washing up, showers, toilets - treatment of it required to remove organic matter and microbes

  -Industry = the haber process ( heated hyrdogen and nitrogen to create ammonia for fertalisers ) - additional treatment is required as it contains harmful chemicals

  -Agriculture = nutrient run-off and slurry - organic matter and microbes need to be removed before use
• What is the first step in the sewage treatment process?

  Screening
• What is the purpose of screening in sewage treatment?

  To remove grit and large objects from sewage
• What happens in sedimentation tanks during primary treatment?

  Sewage settles into heavier sludge and lighter effluent
• What is the role of anaerobic bacteria in sewage treatment?

  They change carbon in sludge into methane to be burnt as fuel
• What is the second stage of sewage treatment called?

  Secondary (biological treatment)
• How do aerobic bacteria function in secondary treatment?

  They are pumped in to feed on organic matter
• How long can the secondary treatment process take?

  It can take days
• What is the purpose of secondary settlement tanks?

  To settle and filter out remaining sediment
• What additional treatments can be applied to further sterilize the water?

  Chlorine or UV treatment
• What is a potential danger of using chlorine in sewage treatment?

  Chlorine can be dangerous
• What occurs as a result of metal ore extraction?

  -Landscape scars = large mounds of rock left behind

  -Habitat destruction = destroyed by mining, threatens biodiversity

  -Pollution = noise and air
• Why is copper commonly extracted?

  Malleable, good conductor of heat and electricity, unreactive (great for pipes)
• What are the two solutions to copper-overexploitation?

  -Phytomining = plants grow on contaminated land, absorbing copper ions, plants harvested and burnt, ash contains high concentrations of copper compounds

  -Bioleaching = bacteria is mixed in with low-grade ores, bacteria converts copper into leachate solution, which is then purified to achieve copper compounds
• What is a low grade ore?


  Ores with low or minimal concentration of ore within them
• What are the pros and cons of phytomining?


  PROS : No need for mining, less habitat pollution, less fossil fuels utilised for machinery and extraction

  CONS : large-scale space needed, plants are being burnt (CO2 they have absorbed is being released right back into atmosphere)
• What are the two methods of extracting copper from ores?

  -Displacement

  -Electrolysis
• Explain what goes in in a displacement reaction used to extract copper

  Copper ore is reacted with sulfuric acid to create copper sulphate - this is then reacted with iron (more reactive) - iron takes the place of copper in the solution - copper metal and iron sulphate is formed.
• What are the pros and cons of displacement to extract copper?

  PRO : pure copper is prodcued, low cost reactan (sulfuric acid)

  CON : precious metal is lost in the displacment
• What happens during electrolysis when used to extract copper?

  Copper sulphate solution is poured into the beaker, the positive electrode (anode) is made of impure copper (carrying positive ions) whereas the negative electrode (cathode) is made of pure copper (carrying negative ions), when the battery is connected, Cu ions are pulled towards the negative rod due to their + charge, copper moves from anode to cathode increasing the mass of pure copper.