Chemistry Practicals For Class IX (Science Group) - Experiment No. 4: To purify the given sample of Copper Silphate by crystallization.

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EXPERIMENT NO. 4

TO PURIFY THE GIVEN SAMPLE OF COPPER SULPHATE BY CRYSTALLIZATION.

APPARATUS:

• Beaker
• Funnel
• Glass rod
• Watch glass
• Tripod stand
• Wire gauze
• Bunsen burner (Spirit lamp)
• Filter paper
• Iron stand
• Stirrer

CHEMICALS:

• Impure copper sulphate and distilled water.

CHEMICAL EQUATION:

CuSO₄ + 5H₂O ⇒ CuSO₄.5H₂O

Anhydrous (white)    Penta hydrated (blue)

THEORY:
A solution that cannot dissolve more solute is called saturated solution. If saturated solution is further heated and more solute is added, it dissolves. Now on cooling slowly, at roorn temperature, crystals of pure compound obtained, while impurities remain in solution.

METHOD:

• Take about 40 ml distilled water in the beaker.
• Add small quantity of pulverized impure copper sulphate into the beaker containing water.
• Stir it with glass rod to dissolve it.
• Keep on stirring until whole salt dissolve it.
• Keep on adding and stirring until the time will come when no more salt would be dissolved.
• Pour the solution through filter paper to remove insoluble impurities.
• Now decant the solution into another beaker to separate it from undissolved salt.
• Concentrate the solution by boiling the solution until the volume becomes half.
• Allow the solution to cool at room temperature.
• Decant off supernatant liquid.
• Dry the crystals in a fold of filter paper.

RESULT:
Pure crystals of copper sulphate are obtained.

PRECAUTIONS:

• Saturated solution should be prepared at room temperature.
• Cooling process should be as slow as possible.
• During cooling don't disturb the beaker.

Special Thanks to Sir Sajjad Akber Chandio