CLASS.X-Experiment No.8-To study the Reactivity series of elements

Experiment No.8

To study the Reactivity series of elements

Aim:

1. Observing the action of zinc, iron, copper and aluminium metals for the following salt solutions.
1. Zinc sulphate (ZnSO₄)
2. Copper sulphate (CuSO₄)
3. Ferrous sulphate (FeSO₄)
4. Aluminium sulphate (Al₂(SO₄)₃)
2. Arranging the metals Zinc, Copper, Iron, and Aluminium in the decreasing order of reactivity based on the results obtained from the above.

Materials required:

1. Aluminium foil
2. Zinc granules
3. Copper turnings
4. Iron filings
5. Copper sulphate solution
6. Aluminium sulphate solution
7. Zinc sulphate solution
8. Four 50ml beakers
9. Test tube
10. Test tube stand

Theory:

What is reactivity series?

Different metals have different reactivities with chemical reagents. The metals that form positive ions by losing electrons more readily. A more reactive metal displaces a less reactive metal from salt solution. Such reactions are called displacement reactions. Consider an example, if a small amount of zinc is dipped in copper sulphate solution, zinc is displaced from copper sulphate. The blue colour of copper sulphate fades and colourless zinc sulphate solution is obtained. Therefore zinc is more reactive than copper.

• Aluminium has the ability to displace zinc, iron, copper from their respective salt solutions and therefore is more reactive than them.

Reactions:

2Al(s) + 3ZnSO₄(aq) –→ Al₂(SO₄)₃ 3Zn(s)

2Al(s) + 3FeSO₄(aq) –→ Al₂(SO₄)₃ 3Fe(s)

2Al(s) + 3CuSO₄(aq) –→ Al₂(SO₄)₃ 3Cu(s)

• Zinc has the ability to displace iron, copper from their respective salt solutions and therefore is more reactive than them.

Reactions:

Zn(s) + CuSO₄(aq) –→ ZnSO₄ (aq) + Cu(s)

Zn(s) + FeSO₄(aq) –→ ZnSO₄ (aq) + Fe(s)

Zn(s) + Al₂(SO₄)₃(aq) –→ no reaction

Zn(s) + ZnSO₄(aq) –→ no reaction

• Iron has the ability to displace copper from its salt solution and therefore is more reactive when compared to Cu.

Reactions:

Fe(s) + CuSO₄(aq) –→ FeSO₄ (aq) + Cu(s)

Fe(s) + FeSO₄(aq) –→ no reaction

Fe(s) + Al₂(SO₄)₃(aq) –→ no reaction

Fe(s) + ZnSO₄(aq) –→ no reaction

No reaction occurs when any of the metals from zinc, iron, aluminium, and copper are placed in aqueous solution of Al₂(SO₄)₃.

Therefore from the above, we can conclude the reactivity of elements in the following order –

• Aluminium is more reactive than Zinc.
• Zinc is more reactive than Fe.
• Fe is more reactive than Cu.

Hence Aluminium is the most reactive and Copper being the least reactive metal.

The below table gives you an understanding of the colours exhibited by the metals and their salts:

Compound name	Formula	Colour
Aluminium sulphate	Al2(SO4)3	Colourless
Copper sulphate	CuSO4	Blue
Zinc sulphate	ZnSO4	Colourless
Ferrous sulphate	FeSO4	Light green
Copper	Cu	Reddish brown
Aluminium	Al	White
Zinc	Zn	Silver white
Iron	Fe	Blackish grey

Procedure:

1. Wash four beakers with distilled water, dry them and label them A, B, C, D.
2. Prepare 50 mL solution with 5% concentration by volume of ferrous sulphate, aluminium sulphate, copper sulphate, zinc sulphate.
3. Pour ZnSO₄ in beaker A, FeSO₄ in beaker B, CuSO₄ in beaker C, Add Al₂(SO₄)₃ in beaker D.
4. Wash four test tubes with distilled water and dry them.
5. Put them in a test tube stand and label them as P, Q, R, and S as shown in the figure above.
6. Take 10 mL of the saturated ferrous sulphate (FeSO₄), copper sulphate (CuSO₄), zinc sulphate (ZnSO₄), and aluminium sulphate (Al₂(SO₄)₃ ) in the test tube as shown in the figure.
7. Take metal strips of aluminium (Al), iron (Fe), copper (Cu), and zinc (Zn). Clean them with sandpaper before using it in the experiment.
8. Now dip one of the four metal strips in all the four test tubes and observe if any colour change occurs in all four test tubes.
9. Continue step 8 with other metal strips by dipping in fresh aqueous solutions of metals and see the displacement reaction.

Observation:

Metal	Dipped in	Observation
Al	ZnSO4	No change in the solution. Zinc metal which is greyish in colour accumulates on Aluminium metal.
Al	CuSO4	Blue solution becomes colourless. Copper metal which appears reddish brown gets accumulated.
Al	Al2(SO4)3	No reaction.
Al	FeSO4	Green solution becomes colourless. Iron metal which appears greyish black gets accumulated.
Fe	ZnSO4	No reaction.
Fe	CuSO4	Solution becomes light green. Copper metal which appears reddish brown gets accumulated.
Fe	Al2(SO4)3	No reaction.
Fe	FeSO4	No reaction.
Zn	ZnSO4	No reaction.
Zn	CuSO4	Blue solution turns colourless. Reddish brown coppers accumulates on Zinc metal.
Zn	Al2(SO4)3	No reaction.
Zn	FeSO4	Light green solution turns colourless. Greyish black iron accumulates on Zinc metal.
Cu	ZnSO4	No reaction.
Cu	CuSO4	No reaction.
Cu	Al2(SO4)3	No reaction.
Cu	FeSO4	No reaction.

Result and Conclusion:

Metals	Inference
Aluminium	Aluminium displaces zinc, copper, and iron from their solutions. Aluminium is the most reactive metal.
Zinc	Zinc displaces copper, and iron from their solutions. Zinc is more reactive than Cu and Fe metal.
Iron	Iron displaces copper from its solution. Therefore copper is less reactive than iron.
Copper	Copper does not displace any metal therefore it is the least reactive.

The decreasing order of reactivity of metals is as follows:

Al

Zn

Fe

Cu

Precautions to be taken during the experiment:

• Use cleanly washed and dried apparatus for the experiment.
• Clean the metals before dipping them in the solution. You can clean it with sandpaper.
• Use small quantities of aluminium sulphate, iron sulphate, copper sulphate and copper sulphate solutions for the experiment.
• Handle the chemicals with care and do not allow them to come in contact with your skin.
• Make sure you wash the test tubes after every observation.
• Wash your hands thoroughly after the experiment as the salt solutions are poisonous.

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