using resources

• corrosion

  when metals react with the substances in their environment and are gradually destroyed
• when aluminum corrodes, aluminum oxide creates a protective layer because it does not crumble off, which stops the rest of the metal corroding
• rust

  corrosion of iron

  iron + oxygen + water -> hydrated iron(III) oxide

  rust flakes off, so the next bit of iron will rust

  2 methods to prevent rusting

  • coating iron: painting it; electroplating; oil or grease for moving parts
  • sacrificial method: place iron with a more reactive metal that will react with oxygen instead of iron

  galvanizing is a mixture of these:

  • zinc coating protects the metal
  • if there is a scratch, zinc around the site is sacrificial
• Haber process

  nitrogen + hydrogen<-> ammonia

  N2 (g) + 3H2 (g) <-> 2NH3 (g)

  ammonia is needed for fertilisers

  nitrogen is from the air

  hydrogen is from methane reacted with steam

  3:1 H:N

  
• haber process steps:

  • reactants are passed over an iron catalyst
  • done at 450º and 200 atmospheres
  • it is a reversible reaction. Some ammonia coverts back to reactants until dynamic equilibrium reached
  • ammonia is cooled and liquefied in the condenser and removed
  • unused reactants are reused
• haber process conditions and reasons

  450º:

  • forward reaction is exothermic, so too high a temperature shifts the equilibrium the wrong way
  • if the temperature was too low, the rate of reaction would be too slow

  200 atmospheres:

  • high pressure increases the yield
  • too high a pressure is too expensive to maintain

  iron catalyst:

  • speeds it up
• NPK fertilisers


  provides plants with essential elements to grow that might not be in the soil

  made of nitrogen, phosphorus and potassium in certain ratios of each other
• NPK fertilisers - nitrogen-containing compounds 


  speeds up plant growth because it is used in proteins

  made from ammonia:

  ammonia + nitric acid -> ammonium nitrate

  NH3 (aq) + NHO3 (aq) -> NH4NO3(aq)

  two methods to obtain nitrogen:

  • industry: done in giant vats; high concentration; very exothermic
  • lab: through titration and crystallisation; smaller scale; takes longer; safer because less heat released
• NPK fertilisers - potassium


  mined from compounds

  either potassium chloride or potassium sulfate
• NPK fertilisers - phosphorus

  mined but phosphorus rock is insoluble so plants cannot absorb the elements out of it

  react with an acid to get soluble phosphate compound:

  + nitric acid -> phosphoric acid + calcium nitrate

  + sulfuric acid -> calcium sulfate + calcium phosphate

  ( called a single superphosphate)

  + phosphoric acid -> calcium phosphate

  (called triple superphosphate)
• Ceramics 


  properties:

  • non-metal solids; not carbon based and have high boiling points
  • insulators (of heat and electricity), brittle and stiff

  what:

  • some are clay - easily molded, good for pottery and bricks
  • some are glass - brittle when thin; soda lime glass is the most common, made of limestone, sand and sodium carbonate
• composites 


  one material is embedded in another

  fibers or fragments are reinforcements

  matrix bind them together

  EG:

  • fibreglass: glass in polymer; low density and very strong
  • carbon fibre: carbon chains or nanotubes in polymer; strong and light (used in sport equipment)
  • wood
  • concrete
• polymers


  qualities affected by how it is made and what it is made of

  different monomers create different strengths of bonds

  they can be insulators, flexible and moldable
• bioleaching

  • bacteria is used to turn copper compounds into copper solution
  • leachate - the substance produced - contains copper ions so electrolysis is used to extract it
• phytomining

  • plants can take up the copper from the ground and it gathers in their leaves because they do not need to use it
  • the plants are harvested, dried and burnt
  • the copper is extracted with electrolysis or displacement with iron
• Life Cycle assessments 


  uses to break down each stage of a products life to see its impact on the environment
• Life Cycle assessment - stages

  getting the material

  • extraction can damage the environment
  • raw materials often need processing which requires energy

  manufacturing and packing

  • uses energy and resources
  • can cause a lot of pollution
  • waste products made and how to dispose of them

  using the product

  • how long it can be used for / how many uses
  • eg fertilisers can damage the environment and burning fuels releases greenhouse gases

  product disposal

  • landfill pollutes land and water
  • energy s used to transport it to landfill
  • incineration produces air pollution
• Life Cycle assessment - problems

  Is objective

  selective LCA's are used to support companies claims

  some waste is not easily quantified
• LCA - to remember stages

  Gaping

  Men

  Ponder

  Understood

  Dominions
• potable water 


  water that has been treated or is naturally safe to drink
• cleaning water

  1. collecting water: surface water (rivers etc); groundwater (in rocks called aquifers)
  2. filter it with a mesh to remove large solids then with sand and gravel
  3. steralisation will kill harmful bacteria and microbes
• desalination 


  done in countries with little fresh water supplies like Kuwait to treat seawater

  requires a lot of energy

  1. neutralise the water pH using a universal indicator so you do not contaminate the water with indicator
  2. do a flame test to test for sodium and a halide test for chlorine (these make sodium chloride, the common salt in the sea
  3. distill the water and retest it
• Treating sewage water

  1. screening, to remove large items
  2. sedimentation, heavy stuff settles and forms sludge, lighter effluent floats
  3. EFFLUENT ONLY - aerobic digestion: oxygen is pumped through the water so bacteria will break down any organic matter
  4. It is then released into the environment

  3. SLUDGE - anaerobic digestion takes place with releases methane

  4. methane used as gas fuel and digested waste is used as a fertiliser
• waste water treatment

  has more processes than fresh water

  can be an alternative to desalination because it requires less energy but people are opposed to drinking past sewage water

  - Singapore are already doing it

  If toxic matter present, further steps are taken to treat it with chemicals, UV or using membranes