Practical: Prepare Copper(II) Sulfate (Edexcel IGCSE Chemistry (Modular))
Revision Note
Practical: Prepare Copper(II)Sulfate
Aim
To prepare a pure, dry sample of hydrated copper(II) sulfate crystals
Materials
1.0 mol / dm3 dilute sulfuric acid
Copper(II) oxide
Spatula & glass rod
Measuring cylinder & 100 cm3 beaker
Bunsen burner
Tripod, gauze & heatproof mat
Filter funnel & paper, conical flask
Evaporating basin and dish.
Diagram
Preparation of a soluble salt from an insoluble base and acid
The preparation of copper(II) sulfate by the insoluble base method
Method
Add 50 cm3 dilute acid into a beaker and warm gently using a Bunsen burner
Add the copper(II) oxide slowly to the hot dilute acid and stir until the base is in excess (i.e. until the base stops dissolving and a suspension of the base forms in the acid)
Filter the mixture into an evaporating basin to remove the excess base
Gently heat the solution in a water bath or with an electric heater to evaporate the water and to make the solution saturated
Check the solution is saturated by dipping a cold glass rod into the solution and seeing if crystals form on the end
Leave the filtrate in a warm place to dry and crystallise
Decant excess solution and allow the crystals to dry
Practical Tip
The base is added in excess to use up all of the acid, which would become dangerously concentrated during the evaporation and crystallisation stages
Results
Hydrated copper(II) sulfate crystals should be bright blue and regularly shaped
Examiner Tip
Make sure you learn the names of all the laboratory apparatus used in the preparation of salts.
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