Chapter 2, Problem 2.9EP

(a)

Interpretation Introduction

Interpretation:

The molecular formula for the given hydrocarbon has to be identified.

Concept Introduction:

Hydrocarbons are the organic compounds that contain only hydrogen and carbon atoms.  Hydrocarbon derivatives are the one in which the compounds contain hydrogen and carbon atoms along with one or more additional elements.  The additional elements that can be present in hydrocarbon derivatives are oxygen, nitrogen, sulphur, chlorine, bromine etc.

Hydrocarbons are further classified into two categories.  They are saturated hydrocarbons and unsaturated hydrocarbons.  The hydrocarbons that contain single bonds between carbon atoms in the entire molecule is known as saturated hydrocarbon.  The hydrocarbons that contain atleast one double or triple bond between two carbon atoms in the entire molecule is known as unsaturated hydrocarbon.

Saturated hydrocarbons are alkanes.  Unsaturated hydrocarbons are alkene, alkyne and aromatic hydrocarbons.

Alkane has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  Alkene in which one double is present has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkyne in which one triple bond is present has the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Cycloalkenes in which one double bond is present have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Answer to Problem 2.9EP

The molecular formula of the given alkene is ${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}$.

Explanation of Solution

Alkenes are one of the types of unsaturated hydrocarbon.  Alkenes contain double bond as the functional group.  General molecular formula of alkene which contains one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.

Given hydrocarbon in the problem statement is said to have 4-carbon alkene with one double bond.  Hence, “n” is 4.  Substituting it in the general molecular formula as shown below gives the molecular formula of alkene,

    $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\left(\text{2*4}\right)}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{8}}\end{array}$

Therefore, the molecular formula of alkene that contains four carbon atoms with a double bond is ${\text{C}}_{\text{4}}{\text{H}}_{\text{8}}$.

Conclusion

The molecular formula of the given alkene is identified.

(b)

Interpretation Introduction

Interpretation:

The molecular formula for the given hydrocarbon has to be identified.

Concept Introduction:

Hydrocarbons are the organic compounds that contain only hydrogen and carbon atoms.  Hydrocarbon derivatives are the one in which the compounds contain hydrogen and carbon atoms along with one or more additional elements.  The additional elements that can be present in hydrocarbon derivatives are oxygen, nitrogen, sulphur, chlorine, bromine etc.

Hydrocarbons are further classified into two categories.  They are saturated hydrocarbons and unsaturated hydrocarbons.  The hydrocarbons that contain single bonds between carbon atoms in the entire molecule is known as saturated hydrocarbon.  The hydrocarbons that contain atleast one double or triple bond between two carbon atoms in the entire molecule is known as unsaturated hydrocarbon.

Saturated hydrocarbons are alkanes.  Unsaturated hydrocarbons are alkene, alkyne and aromatic hydrocarbons.

Alkane has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  Alkene in which one double is present has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkyne in which one triple bond is present has the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Cycloalkenes in which one double bond is present have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Answer to Problem 2.9EP

The molecular formula of the given alkene is ${\text{C}}_{\text{4}}{\text{H}}_{\text{6}}$.

Explanation of Solution

Alkenes are one of the types of unsaturated hydrocarbon.  Alkenes contain double bond as the functional group.  General molecular formula of alkene which contains two double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Given hydrocarbon in the problem statement is said to have 4-carbon alkene with two double bonds.  Hence, “n” is 4.  Substituting it in the general molecular formula as shown below gives the molecular formula of alkene,

    $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\left(\text{2*4}\right)-2}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{6}}\end{array}$

Therefore, the molecular formula of alkene that contains four carbon atoms with a double bond is ${\text{C}}_{\text{4}}{\text{H}}_{\text{6}}$.

Conclusion

The molecular formula of the given alkene is identified.

(c)

Interpretation Introduction

Interpretation:

The molecular formula for the given hydrocarbon has to be identified.

Concept Introduction:

Hydrocarbons are the organic compounds that contain only hydrogen and carbon atoms.  Hydrocarbon derivatives are the one in which the compounds contain hydrogen and carbon atoms along with one or more additional elements.  The additional elements that can be present in hydrocarbon derivatives are oxygen, nitrogen, sulphur, chlorine, bromine etc.

Hydrocarbons are further classified into two categories.  They are saturated hydrocarbons and unsaturated hydrocarbons.  The hydrocarbons that contain single bonds between carbon atoms in the entire molecule is known as saturated hydrocarbon.  The hydrocarbons that contain atleast one double or triple bond between two carbon atoms in the entire molecule is known as unsaturated hydrocarbon.

Saturated hydrocarbons are alkanes.  Unsaturated hydrocarbons are alkene, alkyne and aromatic hydrocarbons.

Alkane has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  Alkene in which one double is present has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkyne in which one triple bond is present has the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Cycloalkenes in which one double bond is present have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Answer to Problem 2.9EP

The molecular formula of the given cycloalkene is ${\text{C}}_{\text{4}}{\text{H}}_{\text{6}}$.

Explanation of Solution

Cycloalkenes are one of the types of unsaturated hydrocarbon.  Cycloalkenes contain double bond as the functional group.  General molecular formula of cycloalkene which contains one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Given hydrocarbon in the problem statement is said to have 4-carbon cycloalkene with one double bond.  Hence, “n” is 4.  Substituting it in the general molecular formula as shown below gives the molecular formula of cycloalkene,

    $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\left(\text{2*4}\right)\text{-2}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{8-2}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{6}}\end{array}$

Therefore, the molecular formula of cycloalkene that contains four carbon atoms with a double bond is ${\text{C}}_{\text{4}}{\text{H}}_{\text{6}}$.

Conclusion

The molecular formula of the given cycloalkene is identified.

(d)

Interpretation Introduction

Interpretation:

The molecular formula for the given hydrocarbon has to be identified.

Concept Introduction:

Hydrocarbons are the organic compounds that contain only hydrogen and carbon atoms.  Hydrocarbon derivatives are the one in which the compounds contain hydrogen and carbon atoms along with one or more additional elements.  The additional elements that can be present in hydrocarbon derivatives are oxygen, nitrogen, sulphur, chlorine, bromine etc.

Hydrocarbons are further classified into two categories.  They are saturated hydrocarbons and unsaturated hydrocarbons.  The hydrocarbons that contain single bonds between carbon atoms in the entire molecule is known as saturated hydrocarbon.  The hydrocarbons that contain atleast one double or triple bond between two carbon atoms in the entire molecule is known as unsaturated hydrocarbon.

Saturated hydrocarbons are alkanes.  Unsaturated hydrocarbons are alkene, alkyne and aromatic hydrocarbons.

Alkane has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  Alkene in which one double is present has general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkyne in which one triple bond is present has the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Cycloalkenes in which one double bond is present have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.

Answer to Problem 2.9EP

The molecular formula of the given cycloalkene is ${\text{C}}_{\text{4}}{\text{H}}_{\text{4}}$.

Explanation of Solution

Cycloalkenes are one of the types of unsaturated hydrocarbon.  Cycloalkenes contain double bond as the functional group.  General molecular formula of cycloalkene which contains two double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.

Given hydrocarbon in the problem statement is said to have 4-carbon cycloalkene with two double bonds.  Hence, “n” is 4.  Substituting it in the general molecular formula as shown below gives the molecular formula of cycloalkene,

    $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\left(\text{2*4}\right)\text{-4}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{8-4}}\\ {\text{C}}_{\text{4}}{\text{H}}_{\text{4}}\end{array}$

Therefore, the molecular formula of cycloalkene that contains four carbon atoms with a double bond is ${\text{C}}_{\text{4}}{\text{H}}_{\text{4}}$.

Conclusion

The molecular formula of the given cycloalkene is identified.