C1- making salts

• How could you prepare a sample of pure, dry copper sulfate crystals from a sample of insoluble copper oxide?

  1. React sulfuric acid with excess copper oxide

  2. Filter to remove the excess copper oxide

  3. Heat the solution to start evaporation

  4. Turn off the heat and leave until all the water has evaporated

  5. Left with copper sulfate crystals
• Safety precautions when preparing a pure dry salt from an insoluble compound

  • Bunsen burner should be turned off or put on the safety flame when not in use
  • Sulfuric acid is corrosive so wear eye protection
• Methods of separating mixtures

  • Filtration
  • Crystallisation
• How can you separate an insoluble product from a solution?

  1. Filtration: Filter paper placed in a funnel over a conical flask

  2. Pour mixture through the funnel

  3. Insoluble product left on the filter paper
• How can you separate soluble solids from solutions?

  1. Evaporation: Place the mixture in an evaporating dish

  2. Slowly heat the solution

  3. The solvent evaporates and the solution becomes more concentrated so crystals will start to form

  4. Keep heating the evaporating dish until you have dry crystals
• How could you separate a soluble solid from a solution, if the solid decomposes when heated?

  1. Crystallisation: Pour the solution into an evaporating dish and heat gently

  2. When the crystals start to form, remove the dish from the heat and leave to cool

  3. Once cold, filter the crystals out of the solution and leave them in a warm place to dry