Preparing Copper(II) Sulphate

A series of free IGCSE Chemistry Activities and Experiments (Cambridge IGCSE Chemistry).

Preparing Copper(II) Sulphate
How to make copper sulphate (soluble salt) from an insoluble base (copper oxide) and sulphuric acid?

Method

1. Pour 25 cm³ of sulfuric acid into a beaker.
   
2. Add in excess copper(II) oxide.
   
3. Heat the beaker and stir until reaction is complete.
   
4. Filter off the unreacted solid, collecting the clear blue solution in an evaporating dish.
   
5. Boil the solution for 2–3 minutes.
   
6. Let the solution cool and watch the crystals grow.

Questions

1. Why does heat speed up the reaction?
   
2. Write word and balanced chemical equations for the reaction taking place.
   
3. What does the fact that there is some unreacted solid left after the reaction tell you about the proportions of reactants used? Why is it important that the reaction is carried out with these proportions?

• Show Answers
  1. Heat makes the particles move faster and have more energy. They will collide more often and with more energy.
  2. copper(II) oxide + sulfuric acid → copper(II) sulphate + water
     CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂(l)
  3. It indicates that the copper oxide was present in excess. This makes sure that all the acid is reacted. This is important because we will be heating the solution after filtration and hot, concentrated acid would be dangerous.

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