using resources

• how do you make soda-lime glass?

  • mix limestone, sodium carbonate, sand (silicon oxide) together
  • heat it in a furnace until it melts
  • when it cools it will solidify into any shape we want
• properties of ceramics

  • hard
  • brittle
  • heat-resistant
  • corrosion resistant
• how are ceramics made?

  shaping and then firing a non-metalic material (like clay) at a high temperature
• 3 examples of clay ceramics

  • brick
  • china
  • porcelain

  (high compressive strength so used for building)
• what is borosilicate glass?

  sand is heated with boron trioxide

  (it has a much higher melting point that soda-lime glass)
• properties of glass

  • transparent
  • strong
  • good thermal insulator (useful for windows)
• 6 common properties of materials

  1. Melting point - the temperature at which a solid melts into a liquid.
  2. Conductivity - how well a material conducts electricity.
  3. Strength - the ability of a material to resist an applied force (it is hard to change the shape of a strong material).
  4. Hardness - how well a material can resist being scratched or indented (hard materials don't scratch).
  5. Brittleness - how easily a material breaks when a force it applied (brittle materials snap easily).
  6. Stiffness - how well a material can resist bending (a stiff material won't bend very much).
• what is a composite material?

  A composite material consists of two or more materials with different properties, that have been combined to produce a material with more desirable properties.
• properties of polymers

  • flexible
  • easily shaped
  • good insulators of heat and electricity
• LDPE = low density poly(ethene)

  1. Conditions: Moderate temperatures, high pressure, catalyst 
  2. Properties: More flexible but weaker
  3. Uses: Carrier bags
• HDPE - high-density poly(ethene)

  1. Conditions: Low temperature/pressure, catalyst
  2. Properties: More rigid but stronger
  3. Uses: Drainpipes
• metal properties

  • high melting and boiling points
  • good conductor of heat and electricity
  • malleable
  • ductile
• what is soda-lime glass mostly used for?

  windows and bottles
• is the melting point of soda-lime glass high or low 


  low = this limits uses
• is the melting point of borosilicate glass high or low?

  high = useful for objects that require heating e.g. kitchenware and labware
• what two materials are composites made of?

  reinforcements- long solid fibres or fragments of one material

  matrix- surrounds reinforcements and binds them together
• what is potable water?

  • water that is safe to drink
  • not pure water (pure water only contains $H_2O$ molecules)
  • level of dissolved salts must be low
  • pH between 6.5-8.5
  • low levels of microbes (such as bacteria) in it
• how is fresh water turned into drinking water?

  • in the UK, rain provides water containing low levels of dissolved substances (fresh water)
  • this is collected in the ground in aquifers and in lakes, rivers and reservoirs

  1. choose an appropriate source of fresh water
  2. pass water through filter beds (wire mesh then gravel and sand) to remove solids like leaves and sticks
  3. sterilise water to kill microbes with chlorine, ozone or ultra-violet light
• how is sea water turned to drinking water?

  • if fresh water is scarce, sea water may be used
  • it has high levels of dissolved minerals so it must be treated by desalination
  • this is done by distillation or reverse osmosis
  • both methods need lots of energy so they're expensive and not practical for producing large quantities of fresh water
• what is reverse osmosis?

  • salty water is passed through a membrane that only allows water molecules to pass through
  • ions and larger molecules are trapped by the membrane
  • requires high pressure to push water through the membrane -> lots of energy