Chapter U5, Problem 17STP

Interpretation Introduction

Interpretation:

The correct reaction of Al with copper (II) chloride needs to be identified.

Concept introduction:

On the basis of metallic and non-metallic nature; elements can be classified as metals and non-metals.

Metals are solid and hard elements with shiny surface. Metals can be arranged in metal reactivity series on the basis of their reactivity. The reactivity of metals decreases down in the meta reactivity series.

Answer to Problem 17STP

Option (d) is the correct option.

Explanation of Solution

Reason for correct option:

According to the metal reactivity series, Al is more reactive metal than Cu. Thus, Al will displace Cu from copper (II) chloride as given below:

${\text{2 Al}}_{\text{(s)}}{\text{+ 3 CuCl}}_{\text{2(aq)}}\stackrel{}{\to }{\text{2 AlCl}}_{\text{3(aq)}}{\text{+ 3 Cu}}_{\text{(s)}}$

Copper will precipitate in the reaction with ${\text{AlCl}}_{\text{3(aq)}}$ in the solution. The oxidation number of Al increases from Al⁰ to Al³+ whereas the oxidation number of copper decreases from Cu²+ to Cu⁰. Increase in oxidation number is called as oxidation therefore in the given reaction aluminum oxidized and copper precipitates.

Conclusion

Reasons for incorrect options: Since the oxidation number of copper decreases from Cu²+ to Cu⁰, thus it reduced and precipitated during reaction.