Chapter 8.1, Problem 3RQ

a.

Interpretation Introduction

Interpretation: A picture of each solution needs to be drawn showing the ions in an aqueous solution of hydrochloric acid and an aqueous solution of lead(II) nitrate.

Concept Introduction: Ionic compounds on dissolving in water result in a solution that contains the separated ions. Due to the polar nature of water, the ions are attracted to the molecules of water.

Answer to Problem 3RQ

Explanation of Solution

Hydrochloric acid and lead(II) nitrate are ionic compounds that means these compounds are formed by complete transfer of electron(s). The chemical formula of hydrochloric acid and lead(II) nitrate is ${\text{HCl and Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}$ respectively. In an aqueous solution of these compounds, they dissociate into ions such as:

  $\begin{array}{l}\text{HCl(aq) }\to {\text{ H}}^{+}{\text{(aq) + Cl}}^{-}\text{(aq)}\\ {\text{Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{ Pb}}^{2+}{\text{(aq) + 2NO}}_3^{-}\text{(aq)}\end{array}$

From the dissociation reaction it is clear that 1 mole of $\text{HCl}$ dissociates to give 1 mole of ${\text{H}}^{+}$ and 1 mole of ${\text{Cl}}^{-}$ whereas 1 mole of ${\text{Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}$ will give 1 mole of ${\text{Pb}}^{2+}$ and 2 moles of ${\text{NO}}_3^{-}$ in the solution. So, the pictorial representation of the ions in an aqueous solution of hydrochloric acid and an aqueous solution of lead(II) nitrate is:

b.

Interpretation Introduction

Interpretation: A picture needs to be drawn when the aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate are mixed.

Concept Introduction: A reaction in which there is a formation of an insoluble salt due to the mixing of solutions containing soluble salts is said to be precipitation reactions.

Answer to Problem 3RQ

Explanation of Solution

The chemical reaction that will take place on mixing aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate will be precipitation reaction as this reaction will lead to the formation of insoluble salt, lead chloride and aqueous nitric acid. The complete balanced reaction for the process is:

  ${\text{2HCl(aq) + Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{ PbCl}}_{\text{2}}{\text{(s) + 2HNO}}_3\text{(aq)}$

So, the pictorial representation after mixing the two aqueous solutions of hydrochloric acid and lead(II) nitrate is:

c.

Interpretation Introduction

Interpretation: The products formed on mixing aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate should be determined.

Concept Introduction: A reaction in which there is a formation of an insoluble salt due to the mixing of solutions containing soluble salts is said to be precipitation reactions.

Answer to Problem 3RQ

The products forme are:

Solid lead chloride, ${\text{PbCl}}_{\text{2}}$ and aqueous nitric acid, ${\text{HNO}}_3$ .

Explanation of Solution

The chemical reaction that will take place on mixing aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate will be precipitation reaction as this reaction will lead to the formation of insoluble salt, lead chloride and aqueous nitric acid. The complete balanced reaction for the process is:

  ${\text{2HCl(aq) + Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{ PbCl}}_{\text{2}}{\text{(s) + 2HNO}}_3\text{(aq)}$

Hence, the products forme are:

Solid lead chloride, ${\text{PbCl}}_{\text{2}}$ and aqueous nitric acid, ${\text{HNO}}_3$ .

d.

Interpretation Introduction

Interpretation: The net ionic equation for the reaction taken place on mixing aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate should be determined.

Concept Introduction: The reaction that involves only the participating ions in the reaction is said to be the net ionic equation.

Answer to Problem 3RQ

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

Explanation of Solution

The chemical reaction that will take place on mixing aqueous solution of hydrochloric acid and aqueous solution of lead(II) nitrate will be precipitation reaction as this reaction will lead to the formation of insoluble salt, lead chloride and aqueous nitric acid. The complete balanced reaction for the process is:

  ${\text{2HCl(aq) + Pb(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{ PbCl}}_{\text{2}}{\text{(s) + 2HNO}}_3\text{(aq)}$

The total ionic equation for the above reaction is:

  ${\text{2H}}^{+}{\text{(aq) + 2Cl}}^{-}{\text{(aq) + Pb}}^{2+}{\text{(aq) + 2NO}}_3^{-}\text{(aq) }\to {\text{ PbCl}}_{\text{2}}{\text{(s) +2H}}^{+}{\text{(aq) + 2NO}}_3^{-}\text{(aq) }$

In the total ionic equation ${\text{2H}}^{+}{\text{(aq) and 2NO}}_3^{-}\text{(aq) }$ are spectator ions. So, the net ionic equation is:

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