Topic 10 - Using Resources

• Resources are needed for:

  • Warmth
  • Shelter
  • Food
  • Transport
• Some natural resources include:

  • Food
  • Wood
  • Fuels
  • Materials e.g cotton

  We supplement these through agriculture, but we are also trying to replace them with synthetic materials
• Sustainability: using natural materials in a way that does not compromise future generations' ability to do the same
• Potable water = water that has low enough levels of dissolved salts and microbes that is safe to drink
• The most effective way of obtaining portable water is by taking it from a freshwater source e.g a river, as this will have very little salt dissolved in it. It is then filtered to remove large insoluble particles then sterilised using Chlorine, Ozone or UV
• Desalination: removal of salt by distillation or reverse osmosis so it is safe to drink. Disadvantage: it requires a lot of energy
• Pure water is too dangerous to drink in large amounts as there isn't anything dissolved in it so the water will move into body cells via osmosis and cause them to become turgid - and possibly burst
• Waste water is produced when we go to the toilet and also from industrial processed
• Harmful chemicals and organic matter must be removed from wasted water before it is released back into the environment
• Process of cleaning wasted water:

  • Screening/grit removal
  • Sedimentation - creating sludge and effluent (can be treated separately)
  • Sludge (Solid) - treated by anaerobic digestion
  • Liquid effluent - aerobic treatment
• The demand for metals is huge. Most metals can be obtained from their ores which are mined from the ground. The pure metal is then obtained by electrolysis or displacement reaction
• Phytomining: Plants absorb copper ions into their roots. The plant is burnt and the copper is obtained from the ash. Very low yield
• Bioleaching: Bacterial produce leachate solutions that contain copper ions that can be extracted. Very low yield
• Life cycle assessment: carried out to predict the impact of a new product on the environment
• Life cycle assessment considerations:

  • Extraction and procession of raw materials
  • Manufacturing and packaging
  • Use over its lifetime
  • Disposal
  • Transportation
• We can reduce our impact by:

  • Using products less
  • Reducing materials and energy needed to make
  • Recycling
• Corrosion is when metals are destroyed over time due to chemical reactions
• Irons rusts when it corrodes due to it reacting with oxygen and water (steel as well as it contains iron)
• Copper corrodes when it reacts with oxygen to make copper oxide (green). Aluminium oxide is white.
• We can cover materials with sacrificial metals that will corrode before the important metal underneath does
• Zinc is used as a sacrificial metal and when a metal is covered in it, it is called galvanising
• Alloys are mixtures of metals to fulfil a specific need
• Bronze: Cooper + Tin

  Brass: copper + zinc

  Jewellery Gold: gold + silver + copper + zinc (24 carat = 100% gold, 18 carat = 75% gold etc)

  Steel: iron + carbon

  Stainless Steel: steel + chromium/nickel (more resistant to corrosion)
• Alloys are stronger than pure metals due to the different sized atoms disrupting the lattice, so layers cannot slide over each other as easily
• Aluminium is used in an alloy when we need to make a low density alloy
• Most glass we use is soda-lime glass - made by heating sand, sodium carbonate + limestone
• Borosilicate glass is made from sand + boron trioxide and has a higher melting point
• Pottery is made from heating shaped clay in a furnace
• Composites are a combination of two materials (not two metals though), with one binding the other, usually resulting in strong and light materials e.g carbon fibre (reinforced polymers)
• We can choose the density of the polymers, depending on the conditions used when making
• HDPE: High Density Polyethene

  LDPE: Low Density Polyethene
• Thermosoftening Polymers melt when heated
• Thermosetting polymers do not melt when heated due to crosslinks between polymers increasing the attractive forces between the layers
• The Haber Process makes ammonia. Nitrogen from the air is reacted with hydrogen from the electrolysis of water. The gases are passed over a catalyst at a temperature of 450 degrees and a pressure of over 200 atm (atmospheres)
• In the haber process, the high pressure favours the forward reaction while a higher temperature increases the rate of reaction (good) but it also favours the reverse reaction (not good) so 400 degrees is a compromise temperature. This is to maximise the yield of ammonia produces while ensuring the reaction also happens at a reasonable rate.
• Plants need nitrogen, phosphorus and potassium so we make fertilisers made from their salts - NPK fetilisers
• Ammonia is used to make ammonium salts. Potassium chloride and potassium sulphate are obtained by mining. Phosphate rock is also mined but is treated with an acid before being added to the fertiliser