Chapter U4.90, Problem 3E

Interpretation Introduction

Interpretation:

The spectator ion needs to be explained.

Concept Introduction:

Spectator ions may be positively charged ion i.e. cation or negatively charged ion i.e. anion. A spectator ion exists in both the sides i.e. the reactant and product side in the chemical reaction.

Explanation of Solution

The example of spectator ion is shown below:

Consider a chemical reaction between copper sulfate and sodium chloride in aqueous solution.

The balanced reaction is shown below:

  $\text{2NaCl}\left(\text{aq}\right)\text{+}{\text{CuSO}}_{\text{4}}\left(\text{aq}\right)\to {\text{2Na}}^{\text{+}}\left(\text{aq}\right)\text{+}{\text{SO}}_{\text{4}}{}^{\text{2-}}\left(\text{aq}\right)\text{+}{\text{CuCl}}_{\text{2}}\left(\text{s}\right)$

The ionic form of the reaction is shown below:

  ${\text{2Na}}^{\text{+}}\left(\text{aq}\right)\text{+}{\text{2Cl}}^{\text{-}}\left(\text{aq}\right)\text{+}{\text{Cu}}^{\text{2+}}\left(\text{aq}\right)\text{+}{\text{SO}}_{\text{4}}{}^{\text{2-}}\left(\text{aq}\right)\to {\text{2Na}}^{\text{+}}\left(\text{aq}\right)\text{+}{\text{SO}}_{\text{4}}{}^{\text{2-}}\left(\text{aq}\right)\text{+}{\text{CuCl}}_{\text{2}}\left(\text{s}\right)$

The sulfate ions and the sodium ions are the spectator ions in the reaction which do not change in both the reactant and the product side of the reaction. The sodium and sulfate ions just “spectate” when the other ions form the copper chloride. The spectator ions cancelled out to each other when net ionic equation is written, so the net ionic equation is shown below:

  ${\text{2Cl}}^{\text{-}}\left(\text{aq}\right)\text{+}{\text{Cu}}^{\text{2+}}\left(\text{aq}\right)\to {\text{CuCl}}_{\text{2}}\left(\text{s}\right)$