Question

You are given samples of three metals-sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivity.

Answer 1

Given three metals-sodium (Na), magnesium (Mg), copper (Cu)

Activity I. When the three given metals Na, Mg and Cu are added to magnesium chloride solution separately taken in three different test tubes, we will find that displacement reactions will take place in the following manner :

$\begin{array}{cc}MgC{l}_2\text{solution}& \text{Metals}\\ \text{Displacement reaction}& \text{Na}\\ \text{No reaction}& \text{Mg}\\ \text{No reaction}& \text{Cu}\end{array}$

This shows that Na is the most reactive metal as it displaces Mg from $MgC{l}_2$ solution.

Activity II. When Na, Mg and Cu metals are taken in three different test tubes and $CuS{O}_4$ solution is added in each test tube, we will find that displacement reactions will take place in the following manner :

$\begin{array}{cc}CuS{O}_4\text{solution}& \text{Metals}\\ \text{Displacement reaction}& \text{Na}\\ \text{Displacement reaction}& \text{Mg}\\ \text{No reaction}& \text{Cu}\end{array}$

This shows that Cu is the least reactive metal.
Order of decreasing reactivity: $Na>Mg>Cu$.