filtration + crystallisation

• what is filtration used for?

  separating solids from liquids or gases
• describe filtration

  • put some filter paper into a funnel
  • pour your mixture into it
  • the liquid part of the mixture runs through the paper
  • leaves behind a solid residue
• what is crystallisation used for?

  separating soluble solids from a solution
• describe crystallisation

  • pour the solution into an evaporating dish + gently heat the solution
  • some water will evaporate + the solution will get more concentrated
  • when some water has evaporated or crystals start to form remove the dish from the heat to cool
  • the salt will start to form crystals, because it becomes insoluble in the cold, highly concentrated solution
  • filter the crystals out of the solution, leave in a warm place to dry
• what is rock salt?

  a mixture of salt and sand
• does salt or sand dissolve in water?

  salt
• how would you separate rock salt?

  • 1st by grinding it up
  • then dissolving it in a beaker + stirring
  • then filtering it through filter paper
  • then evaporating it in a evaporating dish