Chapter 7, Problem 20CR

Interpretation Introduction

(a)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{FeO}}_{(s)}{\text{ + 2 HNO}}_{3(aq)}\to {\text{ Fe(NO}}_3{)}_{2(aq)}{\text{ + H}}_2{\text{O}}_{(l)}$

This is not an oxidation reduction reaction.

Explanation of Solution

${\text{FeO}}_{(s)}{\text{ + HNO}}_{3(aq)}\to {\text{ Fe(NO}}_3{)}_{2(aq)}{\text{ + H}}_2{\text{O}}_{(l)}$

In this unbalanced equation number of NO₃ - ions in reactants side is one and two in the product side. So we place 2 before HNO₃. Then the number of H atoms also gets balanced. Other atoms present in the equation are already balanced. So the balanced equation is,

${\text{FeO}}_{(s)}{\text{ + 2 HNO}}_{3(aq)}\to {\text{ Fe(NO}}_3{)}_{2(aq)}{\text{ + H}}_2{\text{O}}_{(l)}$

This is not an oxidation reduction reaction. Any of those atoms have not changed their oxidation state. They simply have exchanged their anions. So this is a double displacement reaction, as well as due to the formation of water. This is also an acid base reaction.

Interpretation Introduction

(b)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{2 Mg}}_{(s)}{\text{ + 2 CO}}_{2(g)}{\text{ + O}}_{2(g)}\to {\text{ 2 MgCO}}_{3(s)}$

This is an oxidation reduction reaction.

Explanation of Solution

${\text{Mg}}_{(s)}{\text{ + CO}}_{2(g)}{\text{ + O}}_{2(g)}\to {\text{ MgCO}}_{3(s)}$

There are four O atoms in the reactants side but only three in products side. In order to make the numbers equal in both sides, we place 2 before CO₂ and MgCO₃. Then number of Mg atom in the products side becomes two. Therefore we place 2 before Mg. So the balanced equation is,

${\text{2 Mg}}_{(s)}{\text{ + 2 CO}}_{2(g)}{\text{ + O}}_{2(g)}\to {\text{ 2 MgCO}}_{3(s)}$

Mg has oxidized from 0 oxidation state to + 2 oxidation state. O₂ has reduced from its 0 oxidation state to -2 oxidation state. So this is an oxidation reduction reaction.

Interpretation Introduction

(c)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{2 NaOH}}_{(aq)}{\text{ + CuSO}}_4{}_{(aq)}\to {\text{ Cu(OH)}}_2{}_{(s)}{\text{ + Na}}_2{\text{SO}}_4{}_{(aq)}$

This is not an oxidation reduction reaction.

Explanation of Solution

${\text{NaOH}}_{(aq)}{\text{ + CuSO}}_4{}_{(aq)}\to {\text{ Cu(OH)}}_2{}_{(s)}{\text{ + Na}}_2{\text{SO}}_4{}_{(aq)}$

In the unbalanced equation, number of Na atoms in reactants side is one and in products side it’s two. So we place 2 before NaOH. Then the number of OH- ions in both sides becomes equal. Other atoms present in the equation are already balanced. So the balanced equation is,

${\text{2 NaOH}}_{(aq)}{\text{ + CuSO}}_4{}_{(aq)}\to {\text{ Cu(OH)}}_2{}_{(s)}{\text{ + Na}}_2{\text{SO}}_4{}_{(aq)}$

This is not an oxidation reduction reaction as any atom does not change their oxidation state. This is a precipitation reaction as well as a double displacement reaction since the two compounds have simply exchanged their anions.

Interpretation Introduction

(d)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{HI}}_{(aq)}{\text{ + KOH}}_{(aq)}\to {\text{ KI}}_{(aq)}{\text{ + H}}_2{\text{O}}_{(l)}$

This is not an oxidation reduction reaction.

Explanation of Solution

The equation is already balanced. And this is not an oxidation reduction reaction as any atom in the equation does not change their oxidation states. This is an acid base reaction as well as a double displacement reaction, since the two reactants have simply exchanged their anions.

Interpretation Introduction

(e)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{C}}_3{\text{H}}_8{}_{(g)}{\text{ + 5 O}}_2{}_{(g)}\to {\text{ 3 CO}}_2{}_{(g)}{\text{ + 4 H}}_2{\text{O}}_{(g)}$

This is an oxidation reduction reaction.

Explanation of Solution

${\text{C}}_3{\text{H}}_8{}_{(g)}{\text{ + O}}_2{}_{(g)}\to {\text{ CO}}_2{}_{(g)}{\text{ + H}}_2{\text{O}}_{(g)}$

In the unbalanced equation, number of C in reactants side is three but one in products side. So we place 3 before CO₂. Number of H atoms in reactants side is eight, but only two in the products side. So we place 4 before H₂ O. But then the number of O in the products side becomes 10, but there are only two in the reactants side. So we place 5 before O₂. So the balanced equation is,

${\text{C}}_3{\text{H}}_8{}_{(g)}{\text{ + 5 O}}_2{}_{(g)}\to {\text{ 3 CO}}_2{}_{(g)}{\text{ + 4 H}}_2{\text{O}}_{(g)}$

This is an oxidation reduction reaction. O₂ is present as a reactant in this equation. If a non metal reacts with oxygen it is a sign of oxidation reduction reaction. Here the hydrocarbon is oxidized and Oxygen is reduced.

Interpretation Introduction

(f)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{Co(NH}}_3{)}_6{\text{Cl}}_2{}_{(s)}\to {\text{ CoCl}}_2{}_{(s)}{\text{ + 6 NH}}_3{}_{(g)}$

This is not an oxidation-reduction reaction.

Explanation of Solution

${\text{Co(NH}}_3{)}_6{\text{Cl}}_2{}_{(s)}\to {\text{ CoCl}}_2{}_{(s)}{\text{ + NH}}_3{}_{(g)}$

In the unbalanced equation, number of NH₃ ligand in reactants side is six but one in products side. So we place 6 before NH₃. All the other atoms in the equation are already balanced. So the balanced equation is,

${\text{Co(NH}}_3{)}_6{\text{Cl}}_2{}_{(s)}\to {\text{ CoCl}}_2{}_{(s)}{\text{ + 6 NH}}_3{}_{(g)}$

This is not an oxidation reduction reaction as any atom in the equation does not change its oxidation state. This is a decomposition reaction.

Interpretation Introduction

(g)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{2 HCl}}_{(aq)}{\text{ + Pb(C}}_2{\text{H}}_3{\text{O}}_2{)}_2{}_{(aq)}\to {\text{ 2 HC}}_2{\text{H}}_3{\text{O}}_2{}_{(aq)}{\text{ + PbCl}}_2{}_{(s)}$

This is not an oxidation reduction reaction.

Explanation of Solution

${\text{HCl}}_{(aq)}{\text{ + Pb(C}}_2{\text{H}}_3{\text{O}}_2{)}_2{}_{(aq)}\to {\text{ HC}}_2{\text{H}}_3{\text{O}}_2{}_{(aq)}{\text{ + PbCl}}_2{}_{(s)}$

In the unbalanced equation, number of C₂ H₃ O₂ - ligand in the reactants side is two and one in the products side. So we place 2 before HC₂ H₃ O₂. And the number of Cl atoms in reactants side is one but it is two in the product side. So we place 2 before HCl. Then all the other atoms become balanced. So the balanced equation is,

${\text{2 HCl}}_{(aq)}{\text{ + Pb(C}}_2{\text{H}}_3{\text{O}}_2{)}_2{}_{(aq)}\to {\text{ 2 HC}}_2{\text{H}}_3{\text{O}}_2{}_{(aq)}{\text{ + PbCl}}_2{}_{(s)}$

This is not an oxidation reduction reaction as any atom does not change their oxidation states. This is a precipitation reaction as well as a double displacement reaction, since the two reactants have exchanged their anions.

Interpretation Introduction

(h)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{C}}_{12}{\text{H}}_{22}{\text{O}}_{11(s)}\to {\text{ 12 C}}_{(\text{S})}{\text{ + 11 H}}_2{\text{O}}_{(g)}$

This is an oxidation reduction reaction.

Explanation of Solution

${\text{C}}_{12}{\text{H}}_{22}{\text{O}}_{11(s)}\to {\text{ C}}_{(\text{S})}{\text{ + H}}_2{\text{O}}_{(g)}$

In the unbalanced equation, number of C atoms in the reactants side is twelve but in the products side it is one. So we place 12 before C. Number of H atoms in the reactants side is 22, but in the products side it is two. So we place 11 before H₂ O. Then the number of O atoms also becomes equal in both sides. So the balanced equation is,

${\text{C}}_{12}{\text{H}}_{22}{\text{O}}_{11(s)}\to {\text{ 12 C}}_{(\text{S})}{\text{ + 11 H}}_2{\text{O}}_{(g)}$

This is an oxidation reduction reaction. C in C_{1 2} H_{2 2} O_{1 1} is reduced into C. And H in C_{1 2} H_{2 2} O_{1 1} has oxidized into H₂ O. This is also a decomposition reaction.

Interpretation Introduction

(i)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{2 Al}}_{(s)}{\text{ + 6 HNO}}_3\to {\text{ 2 Al(NO}}_3{)}_3{}_{(aq)}{\text{ + 3 H}}_2{}_{(g)}$

This is an oxidation reduction reaction.

Explanation of Solution

${\text{Al}}_{(s)}{\text{ + HNO}}_3\to {\text{ Al(NO}}_3{)}_3{}_{(aq)}{\text{ + H}}_2{}_{(g)}$

In the unbalanced equation, number of NO₃ - ions in the reactants side is one but in the products side it is three. So we place 3 before HNO₃. Then the number of H atoms in the reactants side becomes three, but in the products side it is two. So we place 6 before HNO₃ and 3 before H₂. Then the number of NO₃ - ions becomes six in the reactants side. So we place 2 before Al(NO₃ )₃. Then number of Al atoms in the products side becomes two. So we place 2 before Al. finally the balanced equation is,

${\text{2 Al}}_{(s)}{\text{ + 6 HNO}}_3\to {\text{ 2 Al(NO}}_3{)}_3{}_{(aq)}{\text{ + 3 H}}_2{}_{(g)}$

This is an oxidation reduction reaction. Al has oxidized form its 0 oxidation state to + 3 oxidation state and H has reduced from + 1 oxidation state into 0 oxidation state. This is also a single displacement reaction, since only H is displaced by Al in this reaction.

Interpretation Introduction

(j)

Interpretation:

Given chemical equation should be balanced. Whether the equation can be classified as oxidation-reduction reactions should be mentioned.

Concept Introduction:

Balanced chemical equation gives the details about the identities of the reactants and products and also how much of each reactant and product participate in the reaction. The numbers in the balanced equation (coefficients) enable us to determine how much product we can get from a given quantity of reactants.

Normally the unbalanced equations are balanced by inspection starting with the most complicated molecule. We should determine what coefficient is necessary to equalize the number of each type of atoms on both side of the arrow. The coefficients used should be the smallest integers which balance the equation.

The driving force involved in oxidation- reduction reaction is transfer of electrons between atoms and ions. While one substance is oxidized by losing electrons, another species takes up that electron and get reduced.

Answer to Problem 20CR

${\text{4 B}}_{(s)}{\text{ + 3 O}}_{2(g)}\to {\text{ 2 B}}_2{\text{O}}_3{}_{(s)}$

This is an oxidation reduction reaction.

Explanation of Solution

${\text{B}}_{(s)}{\text{ + O}}_{2(g)}\to {\text{ B}}_2{\text{O}}_3{}_{(s)}$

In the unbalanced equation, number of O atoms in the reactants side is two but in the products side it is three. So we place 3 before O₂ and 2 before B₂ O₃. Then the number of B atoms in the products side becomes four. So we place 4 before B. So the balanced equation is,

${\text{4 B}}_{(s)}{\text{ + 3 O}}_{2(g)}\to {\text{ 2 B}}_2{\text{O}}_3{}_{(s)}$

This is an oxidation reduction reaction. B has oxidized from 0 oxidation state to + 3 oxidation state and O has reduced from 0 oxidation state to -2 oxidation state. This is also a synthesis reaction, since all the reactants are natural state elements forming B₂ O₃.