Observing the action of Zn, Fe, Cu and Al metals on the salt solutions

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Aim

a) To observe the action of Zn, Fe, Cu and Al metals on the following salt solutions:

ZnSO₄ (aq)

FeSO₄ (aq)

CuSO₄ (aq)

Al₂(SO₄)₃ (aq)

b) Arrange Zn, Fe, Cu and Al metals in the decreasing order of reactivity based on the above result.

Apparatus and Chemicals

• Test tubes
• Test tube stand
• Distilled water
• Four metals (Fe, Cu, Al, and Zn)
• FeSO₄ solution
• CuSO₄ solution
• Al₂(SO₄) solution
• ZnSO₄ solution
• Sand paper

Principle

A more reactive metals displaces a less reactive metal from its salt solution. The reactivity of these four metals is in the order Al > Zn > Fe > Cu. As such aluminium will displace Zinc, iron and copper.

2Al + 3ZnSO₄ → Al₂(SO₄)₃ + 3Zn
2Al + 3FeSO₄ → Al₂(SO₄)₃ + 3Fe
2Al + 3CuSO₄ → Al₂(SO₄)₃ + 3Cu

Zinc will displaces iron and copper from their solutions. But it will not displaces aluminium from its salt solution.

Zn + Al₂(SO₄)₃ → No reaction
Zn + FeSO₄ → ZnSO₄ + Fe
Zn + CuSO₄ → ZnSO₄ + Cu

Iron will displace only copper from its salt solution.

Fe + CuSO₄ → FeSO₄ + Cu

Copper can’t displace Al, Zn and Fe

Procedure

• Clean the metals with sand paper and cut into small pieces.
• Take 10 mL each of ZnSO₄, FeSO₄, and CuSO₄ solutions in three test tubes. Add 1-2 small pieces of aluminium to each test tube. Record your observation in the table.
• Take 10 mL each of Al₂(SO₄)₃, FeSO₄ and CuSO₄ solutions in three test tubes. Add 1-2 small pieces of Zinc to each test tube. Record your observations in the table.
• Take 10 mL each of Al₂(SO₄)₃, FeSO₄ and CuSO₄ solutions in three test tubes. Add 1-2 small pieces of iron to each test tube. Record your observations in the table.
• Take 10 mL each of Al₂(SO₄)₃, FeSO₄ and FeSO₄ solutions in three test tubes. Add 1-2 small pieces of copper to each test tube. Record your observations in the table.

Observations

Metal added	Al2(SO4)3 sol.	ZnSO4 sol.	FeSO4 sol.	CuSO4 sol.
Aluminium	—–	Zn is displaced	Fe is displaced	Cu is displaced
Zinc	No reaction	—–	Fe is displaced	Cu is displaced
Iron	No reaction	No reaction	—–	Cu is displaced
Copper	No reaction	No reaction	No reaction	—–

Inference : The order of reactivity of these four metals is ; Al > Zn > Fe > Cu

Precautions

• Use only distilled water for the experiment.
• Add 1-2 drops of conc. H₂SO₄ to clear the solutions of metals salts (if needed).
• Thoroughly clean the apparatus before the experiment.
• Clean the metals pieces with sand paper before experiment.