Aim

To perform and observe the action of copper sulphate solution on iron nails and also to identify the type of reaction involved.

Apparatus and Chemical

• 250 mL beakers (2 Nos.)
• Sand paper
• Filter paper
• Iron nails (new)
• Copper sulphate solution

Principle

Iron is more reactive than copper. As such iron will displace copper from copper sulphate solution. Thus when iron (say in the form of nails) is kept in copper sulphate solution, iron displaces copper from copper sulphate and iron nails are covered with a thin reddish brown layer of copper. The reaction involved in the process is as follows.

Fe + CuSO₄ → FeSO₄ + Cu

CuSO₄ is sky blue in colour and FeSO₄ is pale green in colour. As such the colour of the solution changes from sky blue to pale green after the reaction. This is an example of displacement reaction.

Procedure

• Take nearly 100 mL of copper sulphate solution in 250 mL beaker. Note the colour of the solution
• Take 2-3 iron nails (nearly 3 cm long). The iron nails should be new and free from rust. Clean these nails with a sand paper and wash with water. Note the colour of the iron nails.
• Place these iron nails in the copper sulphate solution and observe the change in colour of copper sulphate solution as well as of iron nails.

• After nearly 15 minutes remove the remove the iron nails from the solution. wash with water and place it on filter paper to dry.
• Note the colour of the solution as well as of iron nails after the reaction.

Observations and Inference

S.No.	Experiment	Observation	Inference
1.	Note the colour of the copper sulphate solution before the experiment	It is sky blue in colour	Copper sulphate solution is sky blue in colour.
2.	Note the colour of the iron nails before the experiment.	steel grey	Iron nails are steel grey in colour.
3.	Note the colour of the nails after the experiment.	Reddish brown	Reddish brown colour of the nails is due for the deposition of copper on iron.
4.	Note the colour of the pale green solution after the experiment.	Pale green	Ferrous sulphate solution is pale green in colour.

Iron nails, which are steel grey in colour, when place in sky blue coloured copper sulphate solution displaces copper from copper sulphate solution. In this process the iron nails are covered with a thin layer of reddish brown coloured copper while the colour of the solution changes from sky blue to light pale green coloured. It is an example of displacement reation.

Precautions

• Iron nails should preferably new.
• Clean the iron nails with a sand paper till the surface of iron nails acquires a shining appearance.
• Iron nails should completely dip in copper sulphate solution.
• Wait for the reaction to complete. It may take more time in winter than in summer. After the reaction solution should be light green in colour.
• Don’t rub the iron nails covered with copper after the experiment.