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Investigatory Project on Relative Reactivity of Metals

 

Investigatory Project on Study of the relative reactivity of metals (Practical)

 

Introduction

 

The relative reactivity of various metals can be conveniently predicted from the electrochemical series. In the electrochemical series different metals are arranged in the increasing order of their standard reduction potentials. Hence the metals occupying higher position in the series are more reactive than those occupying lower positions. Any metal in the electrochemical series can displace all other metals lying below it from the solution of their salts. This confirms that a more reactive metal can displace a less reactive metal from its salt solution. For example, zinc is more reactive than copper. Therefore zinc can displace copper from copper sulphate solution. Thus, by studying the interaction of metals with the salt solution of other metals it is possible to compare the reactivities of different metals.

Aim of the project

 

The aim of the project is to arrange magnesium, iron, zinc and copper in the decreasing order of their reactivities by studying their interaction with salt solutions.

 

Apparatus and Chemicals

 

1. Test tubes and test tube stand

2. Small measuring cylinders

3. 0.25M solution of zinc sulphate, copper sulphate, ferrous sulphate and magnesium sulphate.

 

Procedure

 

(1) Measure out 5 ml. of zinc sulphate, ferrous sulphate and copper sulphate solutions separately into three test tubes.

(ii) Put a piece of clean magnesium wire in each solution.

(iii) After about half an hour, examine the metal surface and note the change in colour of the solution, if any, in all the test tubes. Record the observations.

(iv) Clean the test tubes and perform the experiment with the following combination of metal and salt solutions.

(a) Zinc metal and solutions of magnesium sulphate, ferrous sulphate and copper sulphate.

(b) Iron metal and solutions of magnesium sulphate, zinc sulphate and copper sulphate.

(c) Copper metal and solutions of magnesium sulphate, zinc sulphate and ferrous sulphate.


Metal Added

Salt Solution

Colour of Solution

Appearance of metal surface

Inference

Initial

Final

Mg

Mg

Mg

ZnSO4

FeSO4

CuSO4

 

 

 

 

Zn

Zn

Zn

MgSO4

FeSO4

CuSO4

 

 

 

 

Fe

Fe

Fe

MgSO4

ZnSO4

CuSO4

 

 

 

 

Cu

Cu

Cu

MgSO4

ZnSO4

FeSO4

 

 

 

 

 

Result

 

1. Since Mg displaces all the other three metals from their salt solutions, it is tile most reactive among the four metals.

2. Since Cu does not displace any of these metals from their salt solutions, it is the least reactive among the four.

3. Zn is more reactive than Fe and Cu but less reactive than Mg.

4. Fe is more reactive than Cu but less reactive than Mg and Zn.

5. The order of reactivity of these metals is Mg > Zn > Fe > Cu.

 

Viva Questions and Answers (Lab)

 

1. What is electrochemical series?

Ans: The arrangement of elements according to the increasing value of their standard reduction potentials is termed as electrochemical series otherwise activity series.

 

2. What do you mean by electrode potential?

Ans: Electrode potential is the measure of the tendency of an electrode to lose or gain electrons if in contact with solution of its own ions.

 

3. How does the activity of metals vary in electrochemical series?

Ans: Activity of metals decreases on going down the electrochemical series.

 

4. What is the action of zinc on copper sulphate solution?

Ans: Since Zn is more reactive than Cu, zinc displaces copper from copper sulphate solution. Zn gets oxidised to Zn2+ while Cu2+ gets reduced to Cu,

Zn + CuSO4 ---> ZnSO4 + Cu

 

5. Can we store copper sulphate solution in an aluminium vessel ?

Ans: No. Aluminium, being more reactive than copper, will displace copper horn copper sulphate solution. Aluminium gets oxidised to Al3+ ions and Cu2+ ions get reduced to Cu. So the aluminium container gets corroded.

 

6. Name two metals that will not displace hydrogen from dilute sulphuric acid?

Ans: Copper and silver

 

7. Why copper does not displace hydrogen from dilute sulphuric acid and dilute hydrochloric acid?

Ans: As copper comes below hydrogen in the electrochemical series, it cannot displace hydrogen from dilute sulphuric acid and dilute hydrochloric acid.

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