Chapter 4, Problem 4.77QP

(a)

Interpretation Introduction

Interpretation: A complete and balanced molecular equation and the overall net ionic equations for the given incomplete reactions are to be determined.

Concept introduction: A balanced chemical equation is based on the law of conservation of mass for a closed system. According to this law, the mass of the products formed in a chemical reaction is equal to the mass of the reactants involved in the reaction.

To determine: The complete and balanced molecular equation and the overall net ionic equations for the given incomplete reaction.

Answer to Problem 4.77QP

Solution

The balanced equation for the given reaction is,

$\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_2\left(aq\right)+{\text{Na}}_2{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)+2{\text{NaNO}}_{\text{3}}\left(aq\right)$

The net ionic reaction is,

${\text{Pb}}^{2+}\left(aq\right)+{\text{SO}}_{\text{4}}{}^{2-}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)$

Explanation of Solution

Explanation

The dissociation reaction of $\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ is,

$\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}\left(aq\right)\to {\text{Pb}}^{2+}\left(aq\right)+2{\text{NO}}_{\text{3}}{}^{-}\left(aq\right)$

The dissociation reaction of ${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}$ is,

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

Therefore, the molecular equation for the reaction between $\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ and ${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}$ is,

$\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_2\left(aq\right)+{\text{Na}}_2{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)+{\text{NaNO}}_{\text{3}}\left(aq\right)$

According to the law of conservation of mass, the mass of the reactants that take part in a chemical reaction is equal to the mass of the products formed in the reaction.

In the given reaction, the number of $\text{Pb}$ and $\text{S}$ atom present on the reactant side is equal to their number on the product side. The number of oxygen, sodium and nitrogen atom present on the reactant side is not equal to their number on the product side. The coefficient $2$ is added to ${\text{NaNO}}_{\text{3}}$ present on product side. This balances the number of, oxygen, sodium and nitrogen atoms on either side of the reaction.

The balanced equation for the given reaction is,

$\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_2\left(aq\right)+{\text{Na}}_2{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)+2{\text{NaNO}}_{\text{3}}\left(aq\right)$

According to the solubility rule, group I cations are soluble in the solution.

Therefore, ${\text{NaNO}}_{\text{3}}$ remains in the solution and ${\text{PbSO}}_{\text{4}}$ precipitate out as it is an insoluble salt.

The net ionic reaction is,

${\text{Pb}}^{2+}\left(aq\right)+{\text{SO}}_{\text{4}}{}^{2-}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)$

(b)

Interpretation Introduction

To determine: The complete and balanced molecular equation and the overall net ionic equations.

Answer to Problem 4.77QP

Solution

The net ionic reaction is,

${\text{NiCl}}_{\text{2}}+{\text{NH}}_4{\text{NO}}_3\to \text{No}\text{reaction}$

Explanation of Solution

Explanation

The dissociation reaction of ${\text{NiCl}}_{\text{2}}$ is,

${\text{NiCl}}_{\text{2}}\left(aq\right)\to {\text{Ni}}^{2+}\left(aq\right)+2{\text{Cl}}^{-}\left(aq\right)$

The dissociation reaction of ${\text{NH}}_4{\text{NO}}_3$ is,

${\text{NH}}_4{\text{NO}}_3\left(aq\right)\to {\text{NH}}_4{}^{+}\left(aq\right)+{\text{NO}}_3{}^{-}\left(aq\right)$

According to the solubility rule, nitrates and ammonia chlorides salts are soluble in the solution.

Therefore, both the salts get soluble after mixing, neither will precipitate out as both are soluble salt.

The net ionic reaction is,

${\text{NiCl}}_{\text{2}}+{\text{NH}}_4{\text{NO}}_3\to \text{No}\text{reaction}$

(c)

Interpretation Introduction

To determine: The complete and balanced molecular equation and the overall net ionic equations.

Answer to Problem 4.77QP

Solution

The balanced equation for the given reaction is,

${\text{FeCl}}_{\text{2}}\left(aq\right)+{\text{Na}}_2\text{S}\left(aq\right)\to \text{FeS}\left(s\right)+2\text{NaCl}\left(aq\right)$

The net ionic reaction is,

${\text{Fe}}^{2+}\left(aq\right)+{\text{S}}^{2-}\left(aq\right)\to \text{FeS}\left(s\right)$

Explanation of Solution

Explanation

The dissociation reaction of ${\text{FeCl}}_{\text{2}}$ is,

${\text{FeCl}}_{\text{2}}\left(aq\right)\to {\text{Fe}}^{2+}\left(aq\right)+2{\text{Cl}}^{-}\left(aq\right)$

The dissociation reaction of ${\text{Na}}_{\text{2}}\text{S}$ is,

${\text{Na}}_{\text{2}}\text{S}\left(aq\right)\to 2{\text{Na}}^{+}\left(aq\right)+{\text{S}}^{2-}\left(aq\right)$

Therefore, the molecular equation for the reaction between $\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ and ${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}$ is,

${\text{FeCl}}_{\text{2}}\left(aq\right)+{\text{Na}}_2\text{S}\left(aq\right)\to \text{FeS}\left(s\right)+\text{NaCl}\left(aq\right)$

According to the law of conservation of mass, the mass of the reactants that take part in a chemical reaction is equal to the mass of the products formed in the reaction.

In the given reaction, the number of $\text{Fe}$ and $\text{S}$ atom present on the reactant side is equal to their number on the product side. The number of, sodium and chlorine atom present on the reactant side is not equal to their number on the product side. The coefficient $2$ is added to $\text{NaCl}$ present on product side. This balances the number of, oxygen, sodium and chlorine atoms on either side of the reaction.

The balanced equation for the given reaction is,

${\text{FeCl}}_{\text{2}}\left(aq\right)+{\text{Na}}_2\text{S}\left(aq\right)\to \text{FeS}\left(s\right)+2\text{NaCl}\left(aq\right)$

According to the solubility rule, group $17$ halides are soluble in the solution.

Therefore, $\text{NaCl}$ remains in the solution and $\text{FeS}$ precipitate out as it is an insoluble salt.

The net ionic reaction is,

${\text{Fe}}^{2+}\left(aq\right)+{\text{S}}^{2-}\left(aq\right)\to \text{FeS}\left(s\right)$

(d)

Interpretation Introduction

To determine: The complete and balanced molecular equation and the overall net ionic equations.

Answer to Problem 4.77QP

Solution

The balanced equation for the given reaction is,

${\text{MgSO}}_4\left(aq\right)+{\text{BaCl}}_{\text{2}}\left(aq\right)\to {\text{BaSO}}_4\left(s\right)+{\text{MgCl}}_{\text{2}}\left(aq\right)$

The net ionic reaction is,

${\text{Ba}}^{2+}\left(aq\right)+{\text{SO}}_4{}^{2-}\to {\text{BaSO}}_4\left(s\right)$

Explanation of Solution

Explanation

The dissociation reaction of ${\text{MgSO}}_4$ is,

${\text{MgSO}}_4\left(aq\right)\to {\text{Mg}}^{2+}\left(aq\right)+{\text{SO}}_4{}^{2-}\left(aq\right)$

The dissociation reaction of ${\text{BaCl}}_{\text{2}}$ is,

${\text{BaCl}}_{\text{2}}\left(aq\right)\to {\text{Ba}}^{2+}\left(aq\right)+{\text{Cl}}^{-}\left(aq\right)$

Therefore, the molecular equation for the reaction between $\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ and ${\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}$ is,

${\text{MgSO}}_4\left(aq\right)+{\text{BaCl}}_{\text{2}}\left(aq\right)\to {\text{BaSO}}_4\left(s\right)+{\text{MgCl}}_{\text{2}}\left(aq\right)$

According to the law of conservation of mass, the mass of the reactants that take part in a chemical reaction is equal to the mass of the products formed in the reaction.

The above reaction is balanced equation as all the atoms present on reactant and product side is equal

The balanced equation for the given reaction is,

${\text{MgSO}}_4\left(aq\right)+{\text{BaCl}}_{\text{2}}\left(aq\right)\to {\text{BaSO}}_4\left(s\right)+{\text{MgCl}}_{\text{2}}\left(aq\right)$

According to the solubility rule, group $17$ halides are soluble in the solution.

Therefore, ${\text{MgCl}}_2$ remains in the solution and ${\text{BaSO}}_4$ precipitate out as it is an insoluble salt.

The net ionic reaction is,

${\text{Ba}}^{2+}\left(aq\right)+{\text{SO}}_4{}^{2-}\to {\text{BaSO}}_4\left(s\right)$

Conclusion

The balanced equation for the given reaction is,

$\text{Pb}{\left({\text{NO}}_{\text{3}}\right)}_2\left(aq\right)+{\text{Na}}_2{\text{SO}}_{\text{4}}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)+2{\text{NaNO}}_{\text{3}}\left(aq\right)$

The net ionic reaction is,

${\text{Pb}}^{2+}\left(aq\right)+{\text{SO}}_{\text{4}}{}^{2-}\left(aq\right)\to {\text{PbSO}}_{\text{4}}\left(aq\right)$

The net ionic reaction is,

${\text{NiCl}}_{\text{2}}+{\text{NH}}_4{\text{NO}}_3\to \text{No}\text{reaction}$

The balanced equation for the given reaction is,

${\text{FeCl}}_{\text{2}}\left(aq\right)+{\text{Na}}_2\text{S}\left(aq\right)\to \text{FeS}\left(s\right)+2\text{NaCl}\left(aq\right)$

The net ionic reaction is,

${\text{Fe}}^{2+}\left(aq\right)+{\text{S}}^{2-}\left(aq\right)\to \text{FeS}\left(s\right)$

The balanced equation for the given reaction is,

${\text{MgSO}}_4\left(aq\right)+{\text{BaCl}}_{\text{2}}\left(aq\right)\to {\text{BaSO}}_4\left(s\right)+{\text{MgCl}}_{\text{2}}\left(aq\right)$

The net ionic reaction is, ${\text{Ba}}^{2+}\left(aq\right)+{\text{SO}}_4{}^{2-}\to {\text{BaSO}}_4\left(s\right)$