Chapter U5.18, Problem 8E

Interpretation Introduction

Interpretation: The net ionic equations for two reactions between magnesium and less active metals needs to be written.

Concept introduction: A chemical reaction is a symbolic representation of how reactants react in presence of an adequate amount of temperature and reaction medium to generate a product.

An ionic reaction is a symbolic representation of how ions react in a chemical reaction.

Answer to Problem 8E

The net ionic equations for two reactions between magnesium and less active metals are:

  $\begin{array}{l}\text{3Mg}\left(\text{s}\right)\text{+}{\text{2Al}}^{\text{3+}}\left(\text{aq}\right)\to \text{2Al}\left(\text{s}\right)\text{+}{\text{3Mg}}^{\text{2+}}\left(\text{aq}\right)\\ \text{3Mg}\left(\text{s}\right)\text{+}{\text{2Ag}}^{\text{+}}\left(\text{aq}\right)\to \text{2Ag}\left(\text{s}\right)\text{+}{\text{Mg}}^{\text{2+}}\left(\text{aq}\right)\end{array}$

Explanation of Solution

The activity series of metal in the order of increasing reactivity is:

Gold < Silver < Mercury < Bismuth < Antimony < Hydrogen < Lead < Tin < Nickel < Cobalt < Cadmium < Iron < Chromium < Zinc < Manganese < Aluminium < Calcium < Strontium < Barium < Lithium < Sodium < Potassium.

So, the net ionic equations for two reactions between magnesium and less active metals like Al and Ag is given as:

  $\begin{array}{l}\text{3Mg}\left(\text{s}\right)\text{+}{\text{2Al}}^{\text{3+}}\left(\text{aq}\right)\to \text{2Al}\left(\text{s}\right)\text{+}{\text{3Mg}}^{\text{2+}}\left(\text{aq}\right)\\ \text{3Mg}\left(\text{s}\right)\text{+}{\text{2Ag}}^{\text{+}}\left(\text{aq}\right)\to \text{2Ag}\left(\text{s}\right)\text{+}{\text{Mg}}^{\text{2+}}\left(\text{aq}\right)\end{array}$

Conclusion

  $\begin{array}{l}\text{3Mg}\left(\text{s}\right)\text{+}{\text{2Al}}^{\text{3+}}\left(\text{aq}\right)\to \text{2Al}\left(\text{s}\right)\text{+}{\text{3Mg}}^{\text{2+}}\left(\text{aq}\right)\\ \text{3Mg}\left(\text{s}\right)\text{+}{\text{2Ag}}^{\text{+}}\left(\text{aq}\right)\to \text{2Ag}\left(\text{s}\right)\text{+}{\text{Mg}}^{\text{2+}}\left(\text{aq}\right)\end{array}$

Given above are the two the net ionic equations between magnesium and less active metals.