Chapter 3, Problem 3.100QP

Write balanced equations for the following reactions described in words.

(a)    Pentane burns in oxygen to form carbon dioxide and water.

(b)    Sodium bicarbonate reacts with hydrochloric acid to form carbon dioxide, sodium chloride, and water.

(c)    When heated in an atmosphere of nitrogen, lithium forms lithium nitride.

(d)    Phosphorus trichloride reacts with water to form phosphorus acid and hydrogen chloride.

(e)    Copper(II) oxide heated with ammonia will form copper, nitrogen gas, and water.

Interpretation Introduction

Interpretation:

Balanced chemical equation for burning of pentane in oxygen to form carbon dioxide and water has to be written.

Concept Introduction:

Balanced equation

• Every chemical reaction obliges Law of conservation of mass which states the mass of total amount of the product should be equal to the total mass of the reactants as matter can neither be destroyed nor be created.
• Law of definite proportion states that a chemical compound always contains its constituent elements in a fixed ratio by mass.  It does neither depend on the source of the preparation nor depend on the method of preparation.
• A chemical equation is balanced based on the above two laws.

Answer to Problem 3.100QP

Balanced chemical equation for burning of pentane in oxygen to form carbon dioxide and water is written as,

${\text{C}}_5{H}_{12}{}_{\text{(l)}}\text{+}{\text{8O}}_{2(g)}\stackrel{}{\to }{\text{ 5CO}}_2{}_{\text{(g)}}{\text{ + 6H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Explanation of Solution

Pentane is a hydrocarbon.  Burning of hydrocarbon in oxygen is combustion reaction.  Carbon dioxide and water are the products formed.  The chemical equation for this reaction is written as,

${\text{C}}_5{H}_{12}{}_{\text{(l)}}\text{+}{\text{O}}_{2(g)}\stackrel{}{\to }{\text{ CO}}_2{}_{\text{(g)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The number of C, H, and O atoms are balanced on the basis of Law of conservation of mass and Law of definite proportion.

Hence balanced chemical equation for burning of pentane in oxygen to form carbon dioxide and water is written as,

${\text{C}}_5{H}_{12}{}_{\text{(l)}}\text{+}{\text{8O}}_{2(g)}\stackrel{}{\to }{\text{ 5CO}}_2{}_{\text{(g)}}{\text{ + 6H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Interpretation Introduction

Interpretation:

Balanced chemical equation for reaction of sodium bicarbonate with hydrochloric acid to form carbon dioxide, sodium chloride and water has to be written.

Concept Introduction:

Balanced equation

• Every chemical reaction obliges Law of conservation of mass which states the mass of total amount of the product should be equal to the total mass of the reactants as matter can neither be destroyed nor be created.
• Law of definite proportion states that a chemical compound always contains its constituent elements in a fixed ratio by mass.  It does neither depend on the source of the preparation nor depend on the method of preparation.
• A chemical equation is balanced based on the above two laws.

Answer to Problem 3.100QP

Balanced chemical equation for reaction of sodium bicarbonate with hydrochloric acid to form carbon dioxide, sodium chloride and water is written as,

$NaHC{O}_3{}_{\text{(s)}}\text{+}{\text{HCl}}_{(aq)}\stackrel{}{\to }{\text{ CO}}_2{}_{\text{(g)}}{\text{ + NaCl}}_{\text{(aq)}}+H_2{O}_{(l)}$

Explanation of Solution

Reaction of sodium bicarbonate with hydrochloric acid is an acid-base neutralization reaction.  The chemical equation for this reaction is written as,

$NaHC{O}_3{}_{\text{(s)}}\text{+}{\text{HCl}}_{(aq)}\stackrel{}{\to }{\text{ CO}}_2{}_{\text{(g)}}{\text{ + NaCl}}_{\text{(aq)}}+H_2{O}_{(l)}$

The number of C, H, Cl, Na and O atoms are balanced on the basis of Law of conservation of mass and Law of definite proportion.

Hence balanced chemical equation is written as,

$NaHC{O}_3{}_{\text{(s)}}\text{+}{\text{HCl}}_{(aq)}\stackrel{}{\to }{\text{ CO}}_2{}_{\text{(g)}}{\text{ + NaCl}}_{\text{(aq)}}+H_2{O}_{(l)}$

Interpretation Introduction

Interpretation:

Balanced chemical equation for heating lithium in nitrogen atmosphere forming lithium nitride has to be written.

Concept Introduction:

Balanced equation

• Every chemical reaction obliges Law of conservation of mass which states the mass of total amount of the product should be equal to the total mass of the reactants as matter can neither be destroyed nor be created.
• Law of definite proportion states that a chemical compound always contains its constituent elements in a fixed ratio by mass.  It does neither depend on the source of the preparation nor depend on the method of preparation.
• A chemical equation is balanced based on the above two laws.

Answer to Problem 3.100QP

Balanced chemical equation for heating lithium in nitrogen atmosphere forming lithium nitride is written as,

$6L{i}_{\text{(s)}}\text{+}{\text{N}}_2{}_{(g)}\stackrel{}{\to }2L{i}_3{N}_{(s)}$

Explanation of Solution

The chemical equation for given reaction is written as,

$L{i}_{\text{(s)}}\text{+}{\text{N}}_2{}_{(g)}\stackrel{}{\to }L{i}_3{N}_{(s)}$

The number of Li and N atoms are balanced on the basis of Law of conservation of mass and Law of definite proportion.

Hence balanced chemical equation is written as,

$6L{i}_{\text{(s)}}\text{+}{\text{N}}_2{}_{(g)}\stackrel{}{\to }2L{i}_3{N}_{(s)}$

Interpretation Introduction

Interpretation:

Balanced chemical equation for reaction of phosphorus trichloride with water forming phosphorus acid and hydrogen chloride has to be written.

Concept Introduction:

Balanced equation

• Every chemical reaction obliges Law of conservation of mass which states the mass of total amount of the product should be equal to the total mass of the reactants as matter can neither be destroyed nor be created.
• Law of definite proportion states that a chemical compound always contains its constituent elements in a fixed ratio by mass.  It does neither depend on the source of the preparation nor depend on the method of preparation.
• A chemical equation is balanced based on the above two laws.

Answer to Problem 3.100QP

Balanced chemical equation for reaction of phosphorus trichloride with water forming phosphorus acid and hydrogen chloride is written as,

${\text{PCl}}_{\text{3}}{}_{\text{(l)}}{\text{ + 3H}}_{\text{2}}{\text{O}}_{\text{(l)}}\stackrel{}{\to }{\text{ H}}_{\text{3}}{\text{PO}}_{\text{3}}{}_{\text{(aq)}}{\text{ + 3HCl}}_{\text{(g)}}$

Explanation of Solution

The chemical equation for reaction of phosphorus trichloride with water forming phosphorus acid and hydrogen chloride is written as,

${\text{PCl}}_{\text{3}}{}_{\text{(l)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}\stackrel{}{\to }{\text{ H}}_{\text{3}}{\text{PO}}_{\text{3}}{}_{\text{(aq)}}{\text{ + HCl}}_{\text{(g)}}$

The number of P, Cl, O and H atoms are balanced on the basis of Law of conservation of mass and Law of definite proportion.

Hence balanced chemical equation is written as,

${\text{PCl}}_{\text{3}}{}_{\text{(l)}}{\text{ + 3H}}_{\text{2}}{\text{O}}_{\text{(l)}}\stackrel{}{\to }{\text{ H}}_{\text{3}}{\text{PO}}_{\text{3}}{}_{\text{(aq)}}{\text{ + 3HCl}}_{\text{(g)}}$

Interpretation Introduction

Interpretation:

Balanced chemical equation for heating copper(II) oxide with ammonia forming copper, nitrogen gas and water has to be written.

Concept Introduction:

Balanced equation

• Every chemical reaction obliges Law of conservation of mass which states the mass of total amount of the product should be equal to the total mass of the reactants as matter can neither be destroyed nor be created.
• Law of definite proportion states that a chemical compound always contains its constituent elements in a fixed ratio by mass.  It does neither depend on the source of the preparation nor depend on the method of preparation.
• A chemical equation is balanced based on the above two laws.

Answer to Problem 3.100QP

Balanced chemical equation for heating copper(II) oxide with ammonia forming copper, nitrogen gas and water is written as,

$\text{3}{\text{CuO}}_{\text{(s)}}{\text{ + 2NH}}_3{}_{(g)}\stackrel{}{\to }{\text{ 3Cu}}_{\text{(s)}}{\text{ + N}}_2{}_{\text{(g)}}+3H_2{O}_{(l)}$

Explanation of Solution

The chemical equation for heating copper(II) oxide with ammonia forming copper, nitrogen gas and water is written as,

${\text{CuO}}_{\text{(s)}}{\text{ + 2NH}}_3{}_{(g)}\stackrel{}{\to }{\text{ Cu}}_{\text{(s)}}{\text{ + N}}_2{}_{\text{(g)}}+H_2{O}_{(l)}$

The number of Cu, N, O and H atoms are balanced on the basis of Law of conservation of mass and Law of definite proportion.

Hence balanced chemical equation is written as,

$\text{3}{\text{CuO}}_{\text{(s)}}{\text{ + 2NH}}_3{}_{(g)}\stackrel{}{\to }{\text{ 3Cu}}_{\text{(s)}}{\text{ + N}}_2{}_{\text{(g)}}+3H_2{O}_{(l)}$