Chapter 12, Problem 12.11P

(a)

Interpretation Introduction

Interpretation:

To analyze whether the given statement- There are two classes of unsaturated hydrocarbons-alkenes and alkynes, is true or false.

Concept Introduction:

Hydrocarbons consists of carbon atoms and hydrogen atoms. They are further classified as saturated or unsaturated on the basis that the hydrocarbon has all single bonds, or it involves double or triple bond also.

The hydrocarbon that has all single bond is called as alkane with the general formula $C_n{H}_{2n+2}$

The hydrocarbon that has at least one double bond is called as alkene wit the general formula $C_n{H}_{2n}$

The hydrocarbon that has at least one triple bond is called as alkyne wit the general formula $C_n{H}_{2n-2}$

Answer to Problem 12.11P

There are two classes of unsaturated hydrocarbons-alkenes and alkynes. Thus, the statement is true.

Explanation of Solution

Hydrocarbons consists of carbon atoms and hydrogen atoms. They are further classified as saturated or unsaturated on the basis that the hydrocarbon has all single bonds or it involves double or triple bond also.

The hydrocarbon that has all single bond is called as alkane with the general formula $C_n{H}_{2n+2}$

Example- Ethane

The hydrocarbon that has at least one double bond is called as alkene with the general formula $C_n{H}_{2n}$

Example- Ethene

The hydrocarbon that has at least one triple bond is called as alkyne with the general formula $C_n{H}_{2n-2}$

Example- Ethyene

Since all the bonds in alkenes and alkynes are not single bonds, they are unsaturated hydrocarbons

(b)

Interpretation Introduction

Interpretation:

To analyze whether the given statement- The bulk of the ethylene used by the chemical industry worldwide is obtained from renewable resources , is true or false.

Concept Introduction:

Ethylene is an unsaturated hydrocarbon, with the formula$C_2{H}_4$ and structure given as-

Renewable sources are those sources which when used once can be generated again.e.g. solar energy is a renewable source of energy.

Non-renewable sourcesare those sources which when used once are generated after millions of years e.g. coal and petroleum are non-renewable sources of energy.

The bulk of the ethylene used by the chemical industry worldwide is obtained from non-renewable resources. Thus, the statement is true.

There are several methods by which ethylene is extracted

1. Steam Cracking of-
2. Ethane and propane from natural gas or crude oil
3. Naptha from crude oil
4. Catalytic cracking of gas oil from crude oil

Crude oil and natural gas both are non-renewable sources. Therefore, the bulk of the ethylene used by the chemical industry worldwide is obtained from non-renewable resources

(c)

Interpretation:

To analyze whether the give statement- Ethylene and acetylene are constitutional isomers, is true or false.

Concept Introduction:

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula. For example- 2-Chloro butane and 1-Chloro butane are constitutional isomers.

2-Chlorobutane      1-Chlorobutane

Ethylene and acetylene are not constitutional isomers. Thus, the statement is false.

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula.

The molecular formula for ethylene

  $C_2{H}_4$

The structural formula for ethylene-

The molecular formula for acetylene

  $C_2{H}_2$

The structural formula for acetylene-

Since ethylene and acetylene neither have same molecular formula nor structural formula. So they are not constitutional formula.

(d)

Interpretation:

To analyze whether the give statement- Cyclohexane and 1-hexene are constitutional isomers, is true or false.

Concept Introduction:

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula. For example- 2-Chloro butane and 1-Chloro butane are constitutional isomers.

2-Chlorobutane      1-Chlorobutane

Cyclohexane and 1-hexene are constitutional isomers. Thus, the statement is true.

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula.

The molecular formula for Cyclohexane

  $C_6{H}_{12}$

The structural formula for Cyclohexane -

Cyclohexane

The molecular formula for 1-hexene

  $C_6{H}_{12}$

The structural formula for 1-hexene -

1-hexene

Since, cyclohexane and 1-hexene have same molecular formula and structural formula so, they are constitutional formula.

Answer to Problem 12.11P

The bulk of the ethylene used by the chemical industry worldwide is obtained from non-renewable resources. Thus, the statement is true.

Explanation of Solution

There are several methods by which ethylene is extracted

1. Steam Cracking of-
2. Ethane and propane from natural gas or crude oil
3. Naptha from crude oil
4. Catalytic cracking of gas oil from crude oil

Crude oil and natural gas both are non-renewable sources. Therefore, the bulk of the ethylene used by the chemical industry worldwide is obtained from non-renewable resources

(c)

Interpretation Introduction

Interpretation:

To analyze whether the give statement- Ethylene and acetylene are constitutional isomers, is true or false.

Concept Introduction:

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula. For example- 2-Chloro butane and 1-Chloro butane are constitutional isomers.

2-Chlorobutane      1-Chlorobutane

Answer to Problem 12.11P

Ethylene and acetylene are not constitutional isomers. Thus, the statement is false.

Explanation of Solution

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula.

The molecular formula for ethylene

  $C_2{H}_4$

The structural formula for ethylene-

The molecular formula for acetylene

  $C_2{H}_2$

The structural formula for acetylene-

Since ethylene and acetylene neither have same molecular formula nor structural formula. So they are not constitutional formula.

(d)

Interpretation Introduction

Interpretation:

To analyze whether the give statement- Cyclohexane and 1-hexene are constitutional isomers, is true or false.

Concept Introduction:

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula. For example- 2-Chloro butane and 1-Chloro butane are constitutional isomers.

2-Chlorobutane      1-Chlorobutane

Answer to Problem 12.11P

Cyclohexane and 1-hexene are constitutional isomers. Thus, the statement is true.

Explanation of Solution

There are compounds which have same constituents but differ in the arrangement of atoms in space. The constitutional isomers are those compounds that have same molecular formula but different structural formula.

The molecular formula for Cyclohexane

  $C_6{H}_{12}$

The structural formula for Cyclohexane -

Cyclohexane

The molecular formula for 1-hexene

  $C_6{H}_{12}$

The structural formula for 1-hexene -

1-hexene

Since, cyclohexane and 1-hexene have same molecular formula and structural formula so, they are constitutional formula.