Chapter 8, Problem 40A

Interpretation Introduction

Interpretation :

Molecular equation, complete ionic equation and net ionic equation must be distinguished. Which type of equation most clearly shows the substances that actually react with one another must also be explained.

Concept Introduction :

Molecular equation involves molecules and complete ionic equation involves all the ions involved in the reaction.

Net ionic equation is the one in which ions common to reactant and product side are cancelled.

Answer to Problem 40A

Molecular equation is the representation of a chemical reaction in which all the participants are shown in the form of molecule.

A complete ionic equation is the representation of a chemical reaction in which all the components ions of reactants and products are shown.

A net ionic equation is the one in which spectator (common to reactant and product) ions are cancelled.

A complete ionic equation most clearly shows the substances that actually react with one another.

Explanation of Solution

Molecular equation, complete ionic equation and net ionic equation are explained taking the example of the reaction between lead nitrate and potassium chloride.

  ${\text{Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq)+2KCl(aq)}\to {\text{PbCl}}_{\text{2}}{\text{(s)+2KNO}}_{\text{3}}\text{(aq)}\text{.}$

It is molecular equation.

  ${\text{Pb}}^{\text{2+}}{\text{(aq)+2NO}}_{\text{3}}{}^{\text{-}}{\text{(aq)+2K}}^{\text{+}}{\text{(aq)+2Cl}}^{\text{-}}\text{(aq)}\to {\text{PbCl}}_{\text{2}}{\text{(s)+2K}}^{\text{+}}{\text{(aq)+2NO}}_{\text{3}}{}^{\text{-}}\text{(aq)}\text{.}$

It is complete ionic equation which shows that Pb²+ reacts with Cl- and K+ reacts with NO₃^-.

  ${\text{Pb}}^{\text{2+}}{\text{+2Cl}}^{\text{-}}\text{(aq)}\to {\text{PbCl}}_{\text{2}}\text{(s)}\text{.}$

It is net ionic equation in which all the spectator ligands (K+ and NO₃^-) are removed.

Conclusion

All the salts are matched with the corresponding microscopic pictures of aqueous solutions based on the charge of cation and anion.