Chapter 8, Problem 8.8QP

(a)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (a) is ${\text{2C+O}}_{\text{2}}\to 2\text{CO}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	C	1
2	O	1

• To tally the atoms of product side, place coefficient two. Then check for the atom count.

Reactant side	Atom	Product side
1	C	2
2	O	2

• To balance the carbon atom on reactant side, place coefficient two for carbon and check for the atom count.

${\text{2C+O}}_{\text{2}}\to 2\text{CO}$

Reactant side	Atom	Product side
2	C	2
2	O	2

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as $\text{2C}\text{+}{\text{O}}_{\text{2}}\to 2\text{CO}$

(b)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (b) is ${\text{2C+O}}_{\text{2}}\to 2{\text{CO}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	C	1
3	O	2

• To tally the oxygen atom on both sides, place 1/2 for oxygen on left hand side and again balance the equation.

$\text{C+}\frac{1}{2}{\text{O}}_{\text{2}}\to {\text{CO}}_{\text{2}}$

Reactant side	Atom	Product side
1	C	1
2	O	2

• To give the equation in simple whole number coofficients, multiply both sides by two.

${\text{2C+O}}_{\text{2}}\to 2{\text{CO}}_{\text{2}}$

Reactant side	Atom	Product side
2	C	2
4	O	4

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{2C+O}}_{\text{2}}\to 2{\text{CO}}_{\text{2}}$

(c)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (c) is ${\text{H}}_{\text{2}}{\text{+Br}}_{\text{2}}\to 2\text{HBr}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
2	H	1
2	Br	1

• To tally the bromine and hydrogen atoms, place two on product side and balance the equation

${\text{H}}_{\text{2}}{\text{+Br}}_{\text{2}}\to 2\text{HBr}$

Reactant side	Atom	Product side
2	H	2
2	Br	2

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{H}}_{\text{2}}{\text{+Br}}_{\text{2}}\to 2\text{HBr}$

(d)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (d) is ${\text{2Rb+2H}}_{\text{2}}\text{O}\to 2{\text{RbOH+H}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	Rb	1
1	O	1
2	H	3

• To tally the hydrogen atom count, place 1/2 on right hand side and then balance.

${\text{Rb+H}}_{\text{2}}\text{O}\to \text{RbOH+}\frac{1}{2}{\text{H}}_{\text{2}}$

Reactant side	Atom	Product side
1	Rb	1
1	O	1
2	H	2

• To give the equation in simple whole number coefficients, multiply both sides by two.

  ${\text{2Rb+2H}}_{\text{2}}\text{O}\to 2{\text{RbOH+H}}_{\text{2}}$

Reactant side	Atom	Product side
2	Rb	2
2	O	2
4	H	4

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{2Rb+2H}}_{\text{2}}\text{O}\to 2{\text{RbOH+H}}_{\text{2}}$

(e)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (e) is ${\text{2Mg+O}}_{\text{2}}\to 2\text{MgO}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	Mg	1
2	O	1

• To tally the oxygen atom, multiply two on product side.

${\text{Mg+O}}_{\text{2}}\to 2\text{MgO}$

Reactant side	Atom	Product side
1	Mg	2
2	O	2

• To balance the magnesium atom, multiply magnesium atom on reactant side by two.

${\text{2Mg+O}}_{\text{2}}\to 2\text{MgO}$

Reactant side	Atom	Product side
2	Mg	2
2	O	2

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{2Mg+O}}_{\text{2}}\to 2\text{MgO}$

(f)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (f) is ${\text{2O}}_{\text{3}}\to 3{\text{O}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
3	O	2

• To tally the  oxygen atom on both sides, place 3/2 for oxygen on right hand side and again balance the equation.

${\text{O}}_{\text{3}}\to \frac{3}{2}{\text{O}}_{\text{2}}$

Reactant side	Atom	Product side
3	O	3

• To give the equation in simple whole number coofficients, multiply both sides by two.

${\text{2O}}_{\text{3}}\to 3{\text{O}}_{\text{2}}$

Reactant side	Atom	Product side
6	O	6

Now, the atom count on both sides of the reaction is same, hence the equation is balanced.  The balanced equation is written as ${\text{2O}}_{\text{3}}\to 3{\text{O}}_{\text{2}}$

(g)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (g) is ${\text{2H}}_{\text{2}}{\text{O}}_{\text{2}}\to 2{\text{H}}_{\text{2}}\text{O}+{\text{O}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
2	H	2
2	O	3

• To tally the  oxygen atom on both sides, place 1/2 for oxygen on right hand side and again balance the equation.

${\text{H}}_{\text{2}}{\text{O}}_{\text{2}}\to {\text{H}}_{\text{2}}\text{O}+\frac{1}{2}{\text{O}}_{\text{2}}$

Reactant side	Atom	Product side
2	H	2
2	O	2

• To give the equation in simple whole number coefficients, multiply both sides by two.

${\text{2H}}_{\text{2}}{\text{O}}_{\text{2}}\to 2{\text{H}}_{\text{2}}\text{O}+{\text{O}}_{\text{2}}$

Reactant side	Atom	Product side
4	H	4
4	O	4

Now, the atom count on both sides of the reaction is same, hence the equation is balanced.  The balanced equation is written as ${\text{2H}}_{\text{2}}{\text{O}}_{\text{2}}\to 2{\text{H}}_{\text{2}}\text{O}+{\text{O}}_{\text{2}}$

(h)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (h) is ${\text{N}}_{\text{2}}{\text{+3H}}_{\text{2}}\to 2{\text{NH}}_{\text{3}}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction.  Check for the number of atoms available on both sides

Reactant side	Atom	Product side
2	N	1
2	H	3

• To tally the nitrogen atom, multiply two on right hand side.

${\text{N}}_{\text{2}}{\text{+H}}_{\text{2}}\to 2{\text{NH}}_{\text{3}}$

Reactant side	Atom	Product side
2	N	2
2	H	6

• To balance the hydrogen count, multiply hydrogen on reactant side by three.

• ${\text{N}}_{\text{2}}{\text{+3H}}_{\text{2}}\to 2{\text{NH}}_{\text{3}}$

Reactant side	Atom	Product side
2	N	2
6	H	6

Now, the atom count on both sides of the reaction is same, hence the equation is balanced.  The balanced equation is written as ${\text{N}}_{\text{2}}{\text{+3H}}_{\text{2}}\to 2{\text{NH}}_{\text{3}}$

(i)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (i) is $\text{Zn+2AgCl}\to {\text{ZnCl}}_{\text{2}}\text{+2Ag}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	Zn	1
1	Ag	1
1	Cl	2

• To tally the chlorine atom, multiply silver chloride on left hand side by two.

$\text{Zn+2AgCl}\to {\text{ZnCl}}_{\text{2}}\text{+Ag}$

Reactant side	Atom	Product side
1	Zn	1
2	Ag	1
2	Cl	2

• To balance the silver atom count, place two for silver on right hand side.

• $\text{Zn+2AgCl}\to {\text{ZnCl}}_{\text{2}}\text{+2Ag}$

Reactant side	Atom	Product side
1	Zn	1
2	Ag	2
2	Cl	2

Now, the atom count on both sides of the reaction is same, hence the equation is balanced. The balanced equation is written as $\text{Zn+2AgCl}\to {\text{ZnCl}}_{\text{2}}\text{+2Ag}$

(j)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (j) is ${\text{S}}_{\text{8}}{\text{+8O}}_{\text{2}}\to 8{\text{SO}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
8	S	1
2	O	2

• Multiply the product side by eight

${\text{S}}_{\text{8}}{\text{+O}}_{\text{2}}\to 8{\text{SO}}_{\text{2}}$

Reactant side	Atom	Product side
8	S	8
2	O	16

• Multiply oxygen atom by eight on reactant side

${\text{S}}_{\text{8}}{\text{+8O}}_{\text{2}}\to 8{\text{SO}}_{\text{2}}$

Reactant side	Atom	Product side
8	S	8
16	O	16

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{S}}_{\text{8}}{\text{+8O}}_{\text{2}}\to 8{\text{SO}}_{\text{2}}$

(k)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (k) is ${\text{2NaOH+H}}_{\text{2}}{\text{SO}}_{\text{4}}\to {\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{+2H}}_{\text{2}}\text{O}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	Na	2
1	S	1
5	O	5
3	H	2

• Multiply $\text{NaOH}$ on left hand side by two.

${\text{2NaOH+H}}_{\text{2}}{\text{SO}}_{\text{4}}\to {\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{+H}}_{\text{2}}\text{O}$

Reactant side	Atom	Product side
2	Na	2
1	S	1
6	O	5
4	H	2

• balance hydrogen atom by placing two on water on the product side.

• ${\text{2NaOH+H}}_{\text{2}}{\text{SO}}_{\text{4}}\to {\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{+2H}}_{\text{2}}\text{O}$

Reactant side	Atom	Product side
2	Na	2
1	S	1
6	O	6
4	H	4

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{2NaOH+H}}_{\text{2}}{\text{SO}}_{\text{4}}\to {\text{Na}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{+2H}}_{\text{2}}\text{O}$

(l)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (l) is ${\text{Cl}}_{\text{2}}\text{+2NaI}\to 2{\text{NaCl+I}}_{\text{2}}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	Na	1
2	Cl	1
1	I	2

• To tally the chlorine atom, multiply silver chloride on right hand side by two.

${\text{Cl}}_{\text{2}}\text{+NaI}\to 2{\text{NaCl+I}}_{\text{2}}$

Reactant side	Atom	Product side
1	Na	2
2	Cl	2
1	I	2

• To balance finally, place two on sodium iodide.

• ${\text{Cl}}_{\text{2}}\text{+2NaI}\to 2{\text{NaCl+I}}_{\text{2}}$

Reactant side	Atom	Product side
2	Na	2
2	Cl	2
2	I	2

Now, the atom count on both sides of the reaction is same, hence the equation is balanced.  The balanced equation is written as ${\text{Cl}}_{\text{2}}\text{+2NaI}\to 2{\text{NaCl+I}}_{\text{2}}$

(m)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (m) is ${\text{3KOH+H}}_{\text{3}}{\text{PO}}_{\text{4}}\to {\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{+3H}}_{\text{2}}\text{O}$

Explanation of Solution

• List the atoms of given equation and also the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	K	3
5	O	5
1	P	1
4	H	2

• To tally the potassium atom, multiply potassium hydroxide on left hand side by three.

${\text{3KOH+H}}_{\text{3}}{\text{PO}}_{\text{4}}\to {\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{+H}}_{\text{2}}\text{O}$

Reactant side	Atom	Product side
3	K	3
7	O	5
1	P	1
6	H	2

• Place three on water molecule on the product side

• ${\text{3KOH+H}}_{\text{3}}{\text{PO}}_{\text{4}}\to {\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{+3H}}_{\text{2}}\text{O}$

Reactant side	Atom	Product side
3	K	3
7	O	7
1	P	1
6	H	6

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{3KOH+H}}_{\text{3}}{\text{PO}}_{\text{4}}\to {\text{K}}_{\text{3}}{\text{PO}}_{\text{4}}{\text{+3H}}_{\text{2}}\text{O}$

(n)

Interpretation Introduction

Interpretation: The given set chemical equations has to be balanced.

Concept Introduction:

• Chemical equation is the symbolic representation of a chemical reaction using the symbols of elements. Chemical equation must be balanced on both sides (reactant side and product side) of the reaction. A balanced equation alone obeys the "Law of conservation of mass"
• Balancing a chemical equation is based on "trial-and-error" method.
• For each step during balancing of chemical equation, the atoms involved in reaction are listed out. Then the number of atoms on both sides of the reaction (reactant side and product side) is checked for tally.
• Suitable numerals are placed as coefficients before the element or compound on either side of reaction wherever necessary.
• Placing of coefficients are allowed for balancing equation, whereas changing the subscripts of elements or compounds are not allowed.
• Always place coefficients for compounds first rather than placing it for elements.
• Polyatomic ions can be treated as single unit on both sides rather than considering their constituents individually.
• While balancing the equation, the numerals used must be simple whole number.

Answer to Problem 8.8QP

The balanced chemical equation for (n) is ${\text{CH}}_{\text{4}}{\text{+4Br}}_{\text{2}}\to {\text{CBr}}_{\text{4}}\text{+4HBr}$

Explanation of Solution

• List the atoms of given equation and the number of each atoms present on both sides of the reaction. Check for the number of atoms available on both sides

Reactant side	Atom	Product side
1	C	1
4	H	1
2	Br	5

• Place four on hydrogen bromide of the product side.

${\text{CH}}_{\text{4}}{\text{+Br}}_{\text{2}}\to {\text{CBr}}_{\text{4}}\text{+4HBr}$

Reactant side	Atom	Product side
1	C	1
4	H	4
2	Br	8

• To balance finally, place four on bromine on the left hand side

• ${\text{CH}}_{\text{4}}{\text{+4Br}}_{\text{2}}\to {\text{CBr}}_{\text{4}}\text{+4HBr}$

Reactant side	Atom	Product side
1	C	1
4	H	4
8	Br	8

Now, the atom count on both sides of the reaction is same, hence, the equation is balanced.  The balanced equation is written as ${\text{CH}}_{\text{4}}{\text{+4Br}}_{\text{2}}\to {\text{CBr}}_{\text{4}}\text{+4HBr}$