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


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.

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