Chapter 2, Problem 39P

Write a balanced chemical equation for the combustion of each of the following compounds:

a) Decane

b) Cyclodecane

c) Methylcyclononane

d) Cyclopentylcyclopentane

Interpretation Introduction

Interpretation:

A balanced chemical equation for the combustion of each of the given compounds is to be written.

Concept introduction:

Alkanes are inert in acid-base reactions but undergo oxidation-reduction reactions.

During combustion, alkanes undergo oxidation.

This combustion reaction of alkanes is exothermic, and the products formed are carbon dioxide and water.

When balancing the reaction, the carbon and hydrogen is balanced first, leaving oxygen for the last to balance.

Answer to Problem 39P

Solution:

a) ${\text{2C}}_{\text{10}}{\text{H}}_{\text{22}}{\text{+31O}}_{\text{2}}\to {\text{20CO}}_{\text{2}}{\text{+22H}}_{\text{2}}\text{O}$

b) ${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+15O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+10H}}_{\text{2}}\text{O}$

c) ${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+15O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+10H}}_{\text{2}}\text{O}$

d) ${\text{2C}}_{\text{10}}{\text{H}}_{18}{\text{+29O}}_{\text{2}}\to 20{\text{CO}}_{\text{2}}{\text{+18H}}_{\text{2}}\text{O}$

Explanation of Solution

a) Decane

Decane is a straight chain alkane having the molecular formula $C_{10}{H}_{22}$.

The combustion reaction of decane is written as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{22}}{\text{+O}}_{\text{2}}\to {\text{CO}}_{\text{2}}{\text{+H}}_{\text{2}}\text{O}$

To balance this reaction, first, the C and H are balanced.

${\text{C}}_{\text{10}}{\text{H}}_{\text{22}}{\text{+ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+11H}}_{\text{2}}\text{O}$

Oxygen is balanced as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{22}}\text{+}\frac{31}{2}{\text{ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+11H}}_{\text{2}}\text{O}$

The coefficients are converted to whole numbers as follows:

${\text{2C}}_{\text{10}}{\text{H}}_{\text{22}}{\text{+31O}}_{\text{2}}\to {\text{20CO}}_{\text{2}}{\text{+22H}}_{\text{2}}\text{O}$

This is the complete balanced reaction of decane.

b) Cyclodecane

Cyclodecane is a cyclic alkane having the molecular formula $C_{10}{H}_{20}$.

The combustion reaction of cyclodecane is written as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+ O}}_{\text{2}}\to {\text{CO}}_{\text{2}}{\text{+ H}}_{\text{2}}\text{O}$

To balance this reaction, first, the C and H are balanced.

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+ 10H}}_{\text{2}}\text{O}$

Oxygen is balanced as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+15O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+10H}}_{\text{2}}\text{O}$

This is the complete balanced reaction of cyclodecane.

c) Methylcyclononane

Methylcyclononane is a branched chain alkane having the molecular formula $C_{10}{H}_{20}$.

The combustion reaction of methylcyclononane is written as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+ O}}_{\text{2}}\to {\text{CO}}_{\text{2}}{\text{+H}}_{\text{2}}\text{O}$

To balance this reaction, first, the C and H are balanced.

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+ 10H}}_{\text{2}}\text{O}$

Oxygen is balanced as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{20}}{\text{+15O}}_{\text{2}}\to {\text{10CO}}_{\text{2}}{\text{+10H}}_{\text{2}}\text{O}$

This is the complete balanced reaction of methylcyclononane.

d) Cyclopentylcyclopentane

Cyclopentylcyclopentane is a branched chain alkane having the molecular formula $C_{10}{H}_{18}$.

The combustion reaction of Cyclopentylcyclopentane is written as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{18}}{\text{+ O}}_{\text{2}}\to {\text{CO}}_{\text{2}}{\text{+H}}_{\text{2}}\text{O}$

To balance this reaction, first, the C and H balanced.

${\text{C}}_{\text{10}}{\text{H}}_{\text{18}}{\text{+ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+ 9H}}_{\text{2}}\text{O}$

Oxygen is balanced as follows:

${\text{C}}_{\text{10}}{\text{H}}_{\text{18}}\text{+ }\frac{29}{2}{\text{ O}}_{\text{2}}\to 10{\text{CO}}_{\text{2}}{\text{+ 9H}}_{\text{2}}\text{O}$

The coefficients are converted to whole numbers as follows:

${\text{2C}}_{\text{10}}{\text{H}}_{\text{18}}{\text{+ 29 O}}_{\text{2}}\to 20{\text{CO}}_{\text{2}}{\text{+ 18H}}_{\text{2}}\text{O}$

This is the complete balanced reaction of cyclopentylcyclopentane.