Chapter 4, Problem 4.69QP

(a)

Interpretation Introduction

Interpretation:

The given equation ${\text{C}}_{\text{4}}{\text{H}}_{\text{10(g)}}{\text{ + O}}_{\text{2(g)}}\stackrel{}{\to }{\text{ H}}_{\text{2}}{\text{O}}_{\text{(g)}}{\text{ + CO}}_{\text{2(g)}}$ has to be balanced.

Concept Introduction:

Balancing the equation:

• There is a Law for conversion of mass in a chemical reaction i.e., the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the skeletal reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Place suitable coefficients in front of reactants as well as products until the number of atoms on each side (reactants and products) becomes equal.

Explanation of Solution

Given equation:

  ${\text{C}}_{\text{4}}{\text{H}}_{\text{10(g)}}{\text{ + O}}_{\text{2(g)}}\stackrel{}{\to }{\text{ H}}_{\text{2}}{\text{O}}_{\text{(g)}}{\text{ + CO}}_{\text{2(g)}}$

Balancing the chemical Equation:

Count the number of atoms on each side of the reaction.

Atom	Reactant side	Product side
$\text{H}$	10	2
$\text{O}$	2	3
$\text{C}$	4	1

Place suitable coefficient before reactants and products and then check for the number of atoms again.

  ${\text{2C}}_{\text{4}}{\text{H}}_{\text{10(g)}}{\text{ + 13O}}_{\text{2(g)}}\stackrel{}{\to }{\text{ 10H}}_{\text{2}}{\text{O}}_{\text{(g)}}{\text{ + 8CO}}_{\text{2(g)}}$

Atom	Reactant side	Product side
$\text{H}$	20	20
$\text{O}$	26	26
$\text{C}$	8	8

The number of atoms of present on each side of the reaction is same.  Hence, the balanced equation for the given reaction is ${\text{2C}}_{\text{4}}{\text{H}}_{\text{10(g)}}{\text{ + 13O}}_{\text{2(g)}}\stackrel{}{\to }{\text{ 10H}}_{\text{2}}{\text{O}}_{\text{(g)}}{\text{ + 8CO}}_{\text{2(g)}}$

(b)

Interpretation Introduction

Interpretation:

The given equation ${\text{Au}}_{\text{2}}{\text{S}}_{\text{3(s)}}{\text{ + H}}_{\text{2(g)}}\stackrel{}{\to }{\text{Au}}_{\text{(s)}}{\text{ + H}}_{\text{2}}{\text{S}}_{\text{(g)}}$ has to be balanced.

Concept Introduction:

Refer part (a)

Explanation of Solution

Given equation:

  ${\text{Au}}_{\text{2}}{\text{S}}_{\text{3(s)}}{\text{ + H}}_{\text{2(g)}}\stackrel{}{\to }{\text{Au}}_{\text{(s)}}{\text{ + H}}_{\text{2}}{\text{S}}_{\text{(g)}}$

Balancing the chemical Equation:

Count the number of atoms on each side of the reaction.

Atom	Reactant side	Product side
$\text{Au}$	2	1
$\text{S}$	3	1
$\text{H}$	2	2

Place suitable coefficient before reactants and products and then check for the number of atoms again.

  ${\text{Au}}_{\text{2}}{\text{S}}_{\text{3(s)}}{\text{ + 3H}}_{\text{2(g)}}\stackrel{}{\to }{\text{2Au}}_{\text{(s)}}{\text{ + 3H}}_{\text{2}}{\text{S}}_{\text{(g)}}$

Atom	Reactant side	Product side
$\text{Au}$	2	2
$\text{S}$	3	3
$\text{H}$	6	6

The number of atoms of present on each side of the reaction is same.  Hence, the balanced equation for the given reaction is ${\text{Au}}_{\text{2}}{\text{S}}_{\text{3(s)}}{\text{ + 3H}}_{\text{2(g)}}\stackrel{}{\to }{\text{2Au}}_{\text{(s)}}{\text{ + 3H}}_{\text{2}}{\text{S}}_{\text{(g)}}$.

(c)

Interpretation Introduction

Interpretation:

The given equation ${\text{Al(OH)}}_{\text{3(s)}}{\text{ + HCl}}_{\text{(aq)}}\stackrel{}{\to }{\text{ AlCl}}_{\text{3(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$ has to be balanced.

Concept Introduction:

Refer part (a)

Explanation of Solution

Given equation:

  ${\text{Al(OH)}}_{\text{3(s)}}{\text{ + HCl}}_{\text{(aq)}}\stackrel{}{\to }{\text{ AlCl}}_{\text{3(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Balancing the chemical Equation:

Count the number of atoms on each side of the reaction.

Atom	Reactant side	Product side
$\text{Al}$	1	1
$\text{O}$	3	1
$\text{H}$	4	2
$\text{Cl}$	1	3

Place suitable coefficient before reactants and products and then check for the number of atoms again.

  ${\text{Al(OH)}}_{\text{3(s)}}{\text{ + 3HCl}}_{\text{(aq)}}\stackrel{}{\to }{\text{ AlCl}}_{\text{3(aq)}}{\text{ + 3H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Atom	Reactant side	Product side
$\text{Al}$	1	1
$\text{O}$	3	3
$\text{H}$	6	6
$\text{Cl}$	3	3

The number of atoms of present on each side of the reaction is same.  Hence, the balanced equation for the given reaction is ${\text{Al(OH)}}_{\text{3(s)}}{\text{ + 3HCl}}_{\text{(aq)}}\stackrel{}{\to }{\text{ AlCl}}_{\text{3(aq)}}{\text{ + 3H}}_{\text{2}}{\text{O}}_{\text{(l)}}$.

(d)

Interpretation Introduction

Interpretation:

The given equation ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7(s)}}\stackrel{}{\to }{\text{Cr}}_{\text{2}}{\text{O}}_{\text{3(s)}}{\text{ + N}}_{\text{2(g)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(g)}}$ has to be balanced.

Concept Introduction:

Refer part (a)

Explanation of Solution

Given reaction:

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7(s)}}\stackrel{}{\to }{\text{Cr}}_{\text{2}}{\text{O}}_{\text{3(s)}}{\text{ + N}}_{\text{2(g)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(g)}}$

Balancing the chemical Equation:

Count the number of atoms on each side of the reaction.

Atom	Reactant side	Product side
$\text{N}$	2	2
$\text{H}$	8	2
$\text{Cr}$	2	2
$\text{O}$	7	4

Place suitable coefficient before reactants and products and then check for the number of atoms again.

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7(s)}}\stackrel{}{\to }{\text{Cr}}_{\text{2}}{\text{O}}_{\text{3(s)}}{\text{ + N}}_{\text{2(g)}}{\text{ + 4H}}_{\text{2}}{\text{O}}_{\text{(g)}}$

Atom	Reactant side	Product side
$\text{N}$	2	2
$\text{H}$	8	8
$\text{Cr}$	2	2
$\text{O}$	7	7

The number of atoms of present on each side of the reaction is same.  Hence, the balanced equation for the given reaction is ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{7(s)}}\stackrel{}{\to }{\text{Cr}}_{\text{2}}{\text{O}}_{\text{3(s)}}{\text{ + N}}_{\text{2(g)}}{\text{ + 4H}}_{\text{2}}{\text{O}}_{\text{(g)}}$.