resources

• Humans use the earth's resources

  Provide warmth, shelter, food, transport
• Resources produced by agriculture and farming

  • Cotton produced from a plant
  • Trees used for timber or fuel
• Resources produced by agriculture and farming

  • Cotton
  • Wood chips
• Chemistry replacing natural resources with synthetic alternatives

  • Rubber: natural rubber from a tree, synthetic rubber from crude oil
  • Around two-thirds of the world's rubber is now synthetic
• Fossil fuels are finite resources
• Fossil fuels form much slower than they are being used, leading to eventual depletion
• Metal resources are also finite and will run out if used at the current rate
• Wood is a renewable resource that can be replaced as quickly as it is used
• Human activities need to be sustainable


  Meet current needs without preventing future generations from meeting theirs
• Chemistry's role in resource use

  • Artificial fertilizers help grow more food
  • Chemistry helps provide safe drinking water
  • Processes like phyto mining and bio leaching aid in efficient metal extraction
• Analyzing a sample of water for purity

  1. Check the pH of the water using universal indicator paper

  2. Test for dissolved solids by evaporating the water in an evaporating Basin and weighing it before and after evaporation
• Potable water


  Safe to drink
• Pure water


  Contains no dissolved solids such as salts, has a pH of 7 (neutral)
• Potable water is not the same as pure water
• Pure water has a pH of 7
• Potable water may contain dissolved solids and may not have a pH of 7
• Purifying a sample of water by distillation

  Heat the water in a conical flask, let it evaporate, collect the steam in a test tube cooled by ice water, the steam condenses back into pure water
• Distilled water contains no dissolved solids and has a pH of 7, making it pure water
• Producing potable water from fresh water

  1. Use a good source of fresh water

  2. Pass the water through filter beds to remove material such as leaves and suspended particles

  3. Sterilize the water to kill microbes using chlorine
• Producing potable water from salty water

  1. Use desalination to reduce the levels of dissolved minerals down to an acceptable level for potable water

  2. Desalination methods include distillation and reverse osmosis

  3. Both distillation and reverse osmosis reduce the levels of dissolved minerals but require large amounts of energy
• Potable water


  Water that is safe to drink, with low levels of dissolved salts and microbes
• Rainwater provides most of the potable water in the UK
• Sources of fresh water

  • Aquifers
  • Lakes
  • Rivers
  • Reservoirs
• Rainwater collects in the ground in aquifers, lakes, rivers, and reservoirs


  These are good sources of fresh water
• Fresh water in rivers already has very low levels of dissolved minerals
• Seawater has very high levels of dissolved minerals
• In the UK, chlorine is used to sterilize potable water
• In some parts of the world, ozone or ultraviolet light are used to sterilize potable water
• Distillation and reverse osmosis are methods used for desalination to produce potable water
• Both distillation and reverse osmosis require large amounts of energy, making them expensive
• Wastewater treatment

  1. Screening to remove solids and grit

  2. Sedimentation to produce liquid effluent and semi-solid sludge

  3. Anaerobic digestion of sludge by anaerobic bacteria to produce biogas

  4. Aeration to allow aerobic bacteria to digest organic molecules and harmful microorganisms

  5. Final discharge of treated effluent into nearby rivers or the sea
• Humans use a great deal of water, with only a small percentage used for drinking. Water is also used for personal hygiene, flushing toilets, washing clothes, and in agriculture
• Waste water contains a large amount of organic molecules (e.g., from human and feces) and harmful microorganisms such as bacteria
• Biogas is produced by anaerobic bacteria during the digestion of sludge, which can be burned for electricity
• Digested sludge can be used as fertilizers for farming
• Aeration allows aerobic bacteria to digest organic molecules and harmful microorganisms in the liquid effluent
• In some parts of the world, treated sewage is used directly to produce potable water, but this is not done in the UK
• Groundwater from aquifers is usually safe to drink once treated with chlorine
• Aquifers can sometimes be polluted, for example, with fertilizers, so water from aquifers needs to be carefully tested
• Producing potable water directly from wastewater such as sewage requires many purification steps and is only done in water-scarce areas