C8: specification

• define a pure substance

  • in everyday life it means a substance is in is natural state
  • in chemistry, it means it has one element or compound- not mixed with anything else
• identifying a pure substance & mixtures

  • pure substances melt & boil at specific temperatures
  • mixtures boil & melt at a range of temperatures
• Describe a formulation

  • useful mixtures with a specific function made with exact amounts of ingredients to preform its functions
• examples of formulations

  • paint
  • solvents
  • additives
  • binder (resin)
• formulation

  • important in medicine so pills delivers drug to certain part of body & has long shelf life
  • found in cleaning products, fuels, fertillisers, food & drinks
• stationary phase

  molecules cant move
• mobile phase

  molecules can move- always liquid or gas
• chromatography [RP6]

  1. mark pencil line
  2. use glass capillary to put spots
  3. pour solvent; under pencil line
  4. put on lid & let solvent travel
  5. let paper dry & draw solvent line
  6. calculate Rf (substance/solvent)
• explain what Rf value represents

  • ratio of distance travelled by substance by solvent
  • Rf = distance of substance / solvent
  • measure substance from the centre of the spot !!!!!!
• hydrogen test

  • hold lit splint in hydrogen
  • squeaky pop test!
  • hydrogen burns quickly with oxygen
• chlorine test

  • bleaches damp litmus paper = white
• oxygen test

  • glowing splint
  • oxygen = relights
• carbon dioxide

  • bubble carbon dioxide in limewater
  • carbon turns it cloudy