Separation of Mixtures

• WHEN TO USE 


  When to use

  
• Decantation

  • separation process in which a layer of liquid is separated from the solid that has settled at the bottom of the liquid
  • sedimentation -> form of gravitational separation and the settling of sediments in the liquid
  • decantation -> process of pouring liquid from sediment
  • Examples: clay and water
• Filtration 


  • used to separate solid particles from a liquid or gas
  • gravitational filtration -> uses weight of solid-liquid mixture to push the mixture through the filter paper

  1. filter paper is folded to produce a cone shaped filter that fits into funnel
  2. dissolve mixture in water
  3. transfer mixture into filter funnel, make sure to rinse beaker to ensure all mixture is transferred
  4. wash/rinse with small amounts of water
  5. use heat to evaporate filtrate
  6. dry filtrate - if you are collecting the residue, must be rinsed several times and dried

  E.g. tea bags
• Residue 


  insoluble solid
• filtrate 


  soluble (will need to be evaporated off solvent)
• Evaporation and Crystallization 


  • boiling point differences between solid and solvent
  • liquid is heated and changes state into gas
  • cool solution slowly encourage the formation of crystals
  • liquid solvent is evaporated to recover the solid solute

  E.g. Salt water