Making salts

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

  - React sulfuric acid with excess copper oxide - Filter to remove the excess copper oxide - Heat the solution to start evaporation - Turn off the heat and leave until all the water has evaporated - Left with copper sulfate crystals
• Write the chemical equation for the reaction between CuO and H2SO4

  CuO + H2SO4 → CuSO4+ H2O
• What safety precautions need to be considered 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
• What are two methods of separating mixtures?

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

  Filtration: - Filter paper placed in a funnel over a conical flask - Pour mixture through the funnel - Insoluble product left on the filter paper
• How can you separate soluble solids from solutions?

  Evaporation:

  - Place the mixture in an evaporating dish

  - Slowly heat the solution

  - The solvent evaporates and the solution becomes more

  concentrated so crystals will start to form

  - 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?

  Crystallisation:

  - Pour the solution into an evaporating dish and heat gently

  - When the crystals start to form, remove the dish from the heat

  and leave to cool

  - Once cold, filter the crystals out of the solution and leave

  them in a warm place to dry