Required Practical 1 - 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