Chapter 2, Problem 2.28EP

How many hydrogen atoms are present in a molecule of each of the compounds in Problem 13-26?

1. a. 2-methylcyclopentene
2. b. 1,3-cyclopentadiene
3. c. 2,3-dimethylpentane
4. d. 1-ethyl-2-methylcyclohexene

Interpretation Introduction

Interpretation:

The total number of hydrogen atoms present in the given molecule has to be identified.

Concept Introduction:

Organic compounds are the important basis of life.  They include gasoline, coal, dyes, and clothing fibers etc.  The compounds that are obtained from living organisms are termed as organic compounds and those obtained from the earth are known as inorganic compounds.  Organic compounds are found in earth also apart from living organisms.  All the organic compounds contain the element carbon.  Urea was synthesized in the laboratory which is an organic compound.

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.

Alkanes are a class of saturated hydrocarbons that do not contain a ring of carbon atoms but a chain of carbon atoms with carbon‑carbon single bonds.  The general molecular formula for alkanes is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  “n” is the number of carbon atoms present.  Some of the basic examples of alkanes are methane (${\text{CH}}_{\text{4}}$), ethane (${\text{C}}_{\text{2}}{\text{H}}_{\text{6}}$).  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.

Alkenes and cycloalkenes are a class of unsaturated hydrocarbons that contain at least one double bond in its structure.  The general molecular formula for alkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkene with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with one double bond have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.

Answer to Problem 2.28EP

The total number of hydrogen atoms present is 10.

Explanation of Solution

Cycloalkenes are unsaturated hydrocarbons that contain at least one double bond between carbon atoms with ring structure.  The general molecular formula for cycloalkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Structure of 2-methylcyclopentene can be drawn as,

Carbon atoms are present at the intersection and at the end points.  The above structure has five intersections and one end point.  Therefore, there is a total of six carbon atoms.  The total number of hydrogen atoms can be found by substituting in the general molecular formula as shown below,

  $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}\\ {\text{C}}_{\text{6}}{\text{H}}_{\left(\text{2*6}\right)-2}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{10}}\end{array}$

The total number of hydrogen atoms that will be present in the given cycloalkene is found to be ten.

Conclusion

The total number of hydrogen atoms present in the molecule is ten.

Interpretation Introduction

Interpretation:

The total number of hydrogen atoms present in the given molecule has to be identified.

Concept Introduction:

Organic compounds are the important basis of life.  They include gasoline, coal, dyes, and clothing fibers etc.  The compounds that are obtained from living organisms are termed as organic compounds and those obtained from the earth are known as inorganic compounds.  Organic compounds are found in earth also apart from living organisms.  All the organic compounds contain the element carbon.  Urea was synthesized in the laboratory which is an organic compound.

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.

Alkanes are a class of saturated hydrocarbons that do not contain a ring of carbon atoms but a chain of carbon atoms with carbon‑carbon single bonds.  The general molecular formula for alkanes is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  “n” is the number of carbon atoms present.  Some of the basic examples of alkanes are methane (${\text{CH}}_{\text{4}}$), ethane (${\text{C}}_{\text{2}}{\text{H}}_{\text{6}}$).  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.

Alkenes and cycloalkenes are a class of unsaturated hydrocarbons that contain at least one double bond in its structure.  The general molecular formula for alkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkene with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with one double bond have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.

Answer to Problem 2.28EP

The total number of hydrogen atoms present is 6.

Explanation of Solution

Cycloalkenes are unsaturated hydrocarbons that contain at least one double bond between carbon atoms with a ring structure.  The general molecular formula for cycloalkene with two double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.  Structure of 1,3-cyclopentadiene can be drawn as,

Carbon atoms are present at the intersection and at the end points.  The above structure has five intersections and no end points.  Therefore, there is a total of five carbon atoms.  The total number of hydrogen atoms can be found by substituting in the general molecular formula as shown below,

  $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}\\ {\text{C}}_{\text{5}}{\text{H}}_{\left(\text{2*4}\right)-4}\\ {\text{C}}_{\text{5}}{\text{H}}_{\text{6}}\end{array}$

The total number of hydrogen atoms that will be present in the given cycloalkene is found to be six.

Conclusion

The total number of hydrogen atoms present in the molecule is six.

Interpretation Introduction

Interpretation:

The total number of hydrogen atoms present in the given molecule has to be identified.

Concept Introduction:

Organic compounds are the important basis of life.  They include gasoline, coal, dyes, and clothing fibers etc.  The compounds that are obtained from living organisms are termed as organic compounds and those obtained from the earth are known as inorganic compounds.  Organic compounds are found in earth also apart from living organisms.  All the organic compounds contain the element carbon.  Urea was synthesized in the laboratory which is an organic compound.

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.

Alkanes are a class of saturated hydrocarbons that do not contain a ring of carbon atoms but a chain of carbon atoms with carbon‑carbon single bonds.  The general molecular formula for alkanes is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  “n” is the number of carbon atoms present.  Some of the basic examples of alkanes are methane (${\text{CH}}_{\text{4}}$), ethane (${\text{C}}_{\text{2}}{\text{H}}_{\text{6}}$).  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.

Alkenes and cycloalkenes are a class of unsaturated hydrocarbons that contain at least one double bond in its structure.  The general molecular formula for alkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkene with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with one double bond have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.

Answer to Problem 2.28EP

The total number of hydrogen atoms present is 16.

Explanation of Solution

Alkanes are saturated hydrocarbons that contain only single bonds between carbon atoms with no ring structure.  The general molecular formula for alkane is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  Structure of 2,3-dimethylpentane can be drawn as,

Carbon atoms are present at the intersection and at the end points.  The above structure has three intersections and four end points.  Therefore, there is a total of seven carbon atoms.  The total number of hydrogen atoms can be found by substituting in the general molecular formula as shown below,

  $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}\\ {\text{C}}_{\text{7}}{\text{H}}_{\left(\text{2*7}\right)+2}\\ {\text{C}}_{\text{7}}{\text{H}}_{\text{16}}\end{array}$

The total number of hydrogen atoms that will be present in the given alkane is found to be sixteen.

Conclusion

The total number of hydrogen atoms present in the molecule is sixteen.

Interpretation Introduction

Interpretation:

The total number of hydrogen atoms present in the given molecule has to be identified.

Concept Introduction:

Organic compounds are the important basis of life.  They include gasoline, coal, dyes, and clothing fibers etc.  The compounds that are obtained from living organisms are termed as organic compounds and those obtained from the earth are known as inorganic compounds.  Organic compounds are found in earth also apart from living organisms.  All the organic compounds contain the element carbon.  Urea was synthesized in the laboratory which is an organic compound.

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.

Alkanes are a class of saturated hydrocarbons that do not contain a ring of carbon atoms but a chain of carbon atoms with carbon‑carbon single bonds.  The general molecular formula for alkanes is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n+2}}$.  “n” is the number of carbon atoms present.  Some of the basic examples of alkanes are methane (${\text{CH}}_{\text{4}}$), ethane (${\text{C}}_{\text{2}}{\text{H}}_{\text{6}}$).  Cycloalkanes have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.

Alkenes and cycloalkenes are a class of unsaturated hydrocarbons that contain at least one double bond in its structure.  The general molecular formula for alkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$.  Alkene with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with one double bond have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Cycloalkenes with two double bonds have the general molecular formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-4}}$.

Answer to Problem 2.28EP

The total number of hydrogen atoms present is 16.

Explanation of Solution

Cycloalkenes are unsaturated hydrocarbons that contain at least one double bond between carbon atoms with ring structure.  The general molecular formula for cycloalkene with one double bond is ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}$.  Structure of 2-methylcyclopentene can be drawn as,

Carbon atoms are present at the intersection and at the end points.  The above structure has seven intersections and two end points.  Therefore, there is a total of nine carbon atoms.  The total number of hydrogen atoms can be found by substituting in the general molecular formula as shown below,

  $\begin{array}{l}{\text{C}}_{\text{n}}{\text{H}}_{\text{2n-2}}\\ {\text{C}}_{\text{9}}{\text{H}}_{\left(\text{2*9}\right)-2}\\ {\text{C}}_{\text{9}}{\text{H}}_{\text{16}}\end{array}$

The total number of hydrogen atoms that will be present in the given cycloalkene is found to be sixteen.

Conclusion

The total number of hydrogen atoms present in the molecule is sixteen.