Question

Use the following experimental results to rank the three metals( magnesium, aluminum, and zinc) from highest to lowest reactivity.

(a). Mg + Zn(NO₃)₂ ---> reaction occurs

(b). Al   + Zn(NO₃)₂ ---> reaction occurs

(c). Al    + Mg(NO₃)₂ ---> no reaction occurs

Answer 1

• A more reactive metal displaces a less reactive metal from its salt solution.
• If a less reactive metal is added to a metal salt solution there will be no reaction.

1. For reaction a)  Mg + Zn(NO₃)₂ ---> reaction occurs , This means Mg displaces Zinc from its salt solution. Hence, Mg is more reactive than Zn i.e. reactivity of Mg > Zn.
2. Al   + Zn(NO₃)₂ ---> reaction occurs   , This means Al displaces Zinc from its salt solution. Hence, Al is more reactive than Zn i.e. reactivity of Al > Zn.
3. Al    + Mg(NO₃)₂ ---> no reaction occurs. Since no reaction occurs, therefore, Al is less reactive than Mg i.e. reactivity of Al < Mg.

So, from 1,2 and 3, reactivity order of the three elements is: Mg > Al > Zn.

Mg is most reactive and Zn is least reactive among the three elements.