Lab Manual: Reactivity Series | Lab Manuals for Class 10 PDF Download

Objective

(ii) To arrange Zn, Fe, Cu and Al metals in the decreasing order of reactivity based on the above results.

Materials Required
Aluminium foil, copper turnings, zinc granules, iron filings, ferrous sulphate solution, copper sulphate solution, zinc sulphate solution, aluminium sulphate solution, test tubes, test tube stand and four beakers of 50 ml.

Theory

Different metals have different reactivities towards chemical reagents. Some metals are more reactive than others. The metals, which can lose electron more readily to form positive ions are more reactive.
According to the reactivity series (or activity series) of metals, a more reactive metal displaces a less reactive metal from its aqueous salt solution. These reactions are called displacement reactions.
Displacement reactions can be used to find out the relative reactivities of metals.
Example: If a piece of zinc metal is dipped in a solution of copper sulphate, zinc will displace copper from copper sulphate. The blue colour of copper sulphate solution will gradually fade and finally colourless solution of zinc sulphate will be obtained.
It means that zinc has displaced copper from copper sulphate solution, i.e. zinc is more reactive than copper.

• Al can displace Zn, Fe, Cu from their salt solutions, therefore it is more reactive than Zn, Fe and Cu.
  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)
• Zn can displace Fe and Cu from their salt solutions, therefore zinc is more reactive than Fe and Cu.
  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
• Fe can displace copper from copper sulphate solution, therefore it is more reactive than copper
  Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)
  Fe(s) + ZnSO₄ (aq) → No reaction
  Fe(s) + FeSO₄(aq) → No reaction
  Fe(s) + Al₂(SO₄)₃(aq) → No reaction
• Cu cannot displace any of the given metals from their salt solutions, therefore it is least reactive than the other given metals.
• No reaction takes place when any of the metals copper, iron, zinc and aluminium are placed in aqueous aluminium sulphate solution. From this, it can be concluded that aluminium is the most reactive and copper is the least reactive among the given four metals (Fe, Zn, Cu and Al). Thus, the decreasing order of reactivity of metals is
  Al > Zn > Fe > Cu

Metals and their aqueous salt solutions exhibit colours as follows:

Procedure

• Prepare 50 ml solutions of 5% concentration (by volume) of zinc sulphate, iron(II) sulphate, copper(II) sulphate and aluminium sulphate in distilled water in four different beakers. Label these beakers as P, Q, R and S (as shown in Fig.1).
  
• Take about 10 mL of saturated solution of zinc sulphate (ZnSO₄), ferrous sulphate (FeSO₄), copper sulphate (CuSO₄) and aluminium sulphate [Al₂(SO₄)₃] in the respective test tubes (as shown in Fig. 2). Observe the colour of the solutions.
• Take zinc, copper, iron and aluminium metal strips and clean their surfaces.
• Put zinc metal strip in all the four test tubes A, B, C and D and observe the change that follows.
• Repeat the above experiment with other metal strips by dipping them in fresh salt solutions of metal and observe for displacement reactions.

Observation Table

Result
1. The action of metals on respective salt solutions are given below:

• Al metal is able to displace Zn, Fe and Cu from their salt solutions, therefore Al is most reactive.
• Zn metal is able to displace Fe and Cu from their salt solutions therefore, Zn is more reactive than Fe and Cu.
• Fe metal is able to displace Cu from its salt solution, therefore Fe is more reactive than copper.
• Cu is unable to displace any metal (among Al, Fe and Zn) from their salt solutions, therefore Cu is least reactive.

2. The decreasing order of reactivity, based on the above results, follows the order:
Al > Zn > Fe > Cu

Precautions

• All the apparatus should be clean and dry.
• Handle the chemicals carefully.
• Some reactions may occur slowly, so observe the changes carefully.
• Do not touch or taste the chemicals.
• Clean the metals by rubbing them with a piece of sand paper before dipping them in the salt solutions.
• Wash the test tubes after every set of observations of interaction of a particular metal with the four salt solutions.
• For the preparation of solutions use only distilled water and add small quantity of sulphuric acid.
• Clean your hands properly after the experiment because the salt solutions are poisonous.