Chapter 3, Problem 3.13P

Which compound in each pair has the higher boiling point?

a. or c. or

b. or d. or

Interpretation Introduction

(a)

Interpretation: In the given pair, the compound with the higher boiling point is to be predicted.

Concept introduction: Boiling point is defined as the temperature at which the compound is converted to a gaseous state.

The boiling point of compounds depends upon the molecular weight and the intermolecular forces present in the compounds. The intermolecular forces are the forces that exist in between the two or more atoms in a compound. Due to strong intermolecular forces, the molecule will require more energy to break the bonds. The compounds that have ionic bonding and hydrogen bonding will possess higher boiling point.

Answer to Problem 3.13P

In the given pair of compounds, ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}=\text{O}$ has higher boiling point.

Explanation of Solution

The given compounds are ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}={\text{CH}}_{\text{2}}$ and ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}=\text{O}$.

In ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}={\text{CH}}_{\text{2}}$, $\text{C}-\text{C}$ and $\text{C}-\text{H}$ non polar bonds are present due to which Van der Waals forces exist in the compound. On the other hand, in ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}=\text{O}$, an oxygen atom is present which is more electronegative than carbon atom. Therefore, the formation of partial positive and negative charges occurs on carbon and oxygen atom respectively due to which dipole-dipole interaction exist in the compound.

The increasing order of boiling point with intermolecular forces is,

$\begin{array}{l}\text{Compound with Van der Waals force}<\text{Compound with dipole-dipole interaction}\\ <\text{Compound with hydrogen bonding}\end{array}$

Hence, the boiling point of ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}=\text{O}$ is higher than ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}={\text{CH}}_{\text{2}}$.

Conclusion

In the given pair of compounds, ${\left({\text{CH}}_{\text{3}}\right)}_{\text{2}}\text{C}=\text{O}$ has higher boiling point.

Interpretation Introduction

(b)

Interpretation: In the given pair, the compound with the higher boiling point is to be predicted.

Concept introduction: Boiling point is defined as the temperature at which the compound is converted to a gaseous state.

The boiling point of compounds depends upon the molecular weight and the intermolecular forces present in the compounds. The intermolecular forces are the forces that exist in between the two or more atoms in a compound. Due to strong intermolecular forces, the molecule will require more energy to break the bonds. The compounds that have ionic bonding and hydrogen bonding will possess higher boiling point.

Answer to Problem 3.13P

In the given pair of compounds, ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{COOH}$ has higher boiling point.

Explanation of Solution

The given compounds are ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{COOH}$ and ${\text{CH}}_{\text{3}}{\text{COOCH}}_{\text{3}}$.

In ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{COOH}$, oxygen atoms are present which are more electronegative than carbon atoms. Therefore, the formation of partial positive and negative charges occurs on carbon and oxygen atom respectively due to which dipole-dipole interaction exist in the compound. Also, $\text{C}-\text{C}$ and $\text{C}-\text{H}$ non polar bonds are present due to which Van der Waals forces exist in the compound. It has carboxylic acid group $\left(-\text{COOH}\right)$. Due to the presence of $-\text{OH}$ bond, the intermolecular hydrogen bonding is present in the compound. On the other hand in ${\text{CH}}_{\text{3}}{\text{COOCH}}_{\text{3}}$ Van der Waals forces and dipole-dipole interactions are present. Hence, ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{COOH}$ has higher boiling point than ${\text{CH}}_{\text{3}}{\text{COOCH}}_{\text{3}}$.

Conclusion

In the given pair of compounds, ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{COOH}$ has higher boiling point.

Interpretation Introduction

(c)

Interpretation: In the given pair, the compound with the higher boiling point is to be predicted.

Concept introduction: Boiling point is defined as the temperature at which the compound is converted to a gaseous state.

The boiling point of compounds depends upon the molecular weight and the intermolecular forces present in the compounds. The intermolecular forces are the forces that exist in between the two or more atoms in a compound. Due to strong intermolecular forces, the molecule will require more energy to break the bonds. The compounds that have ionic bonding and hydrogen bonding will possess higher boiling point.

Answer to Problem 3.13P

In the given pair of compounds, ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_5{\text{CH}}_{\text{3}}$ has higher boiling point.

Explanation of Solution

The given compounds are ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{CH}}_{\text{3}}$ and ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_5{\text{CH}}_{\text{3}}$.

In both the compounds, $\text{C}-\text{C}$ and $\text{C}-\text{H}$ non polar bonds are present due to which Van der Waals forces exist in the compounds. But the surface area of ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_5{\text{CH}}_{\text{3}}$ is greater than ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{CH}}_{\text{3}}$ because it is larger molecule as compared to ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{CH}}_{\text{3}}$. Thus, greater is the surface area, higher is the boiling point. Hence, ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_5{\text{CH}}_{\text{3}}$ has higher boiling point.

Conclusion

In the given pair of compounds, ${\text{CH}}_{\text{3}}{\left({\text{CH}}_{\text{2}}\right)}_5{\text{CH}}_{\text{3}}$ has higher boiling point.

Interpretation Introduction

(d)

Interpretation: In the given pair, the compound with the higher boiling point is to be predicted.

Concept introduction: Boiling point is defined as the temperature at which the compound is converted to a gaseous state.

The boiling point of compounds depends upon the molecular weight and the intermolecular forces present in the compounds. The intermolecular forces are the forces that exist in between the two or more atoms in a compound. Due to strong intermolecular forces, the molecule will require more energy to break the bonds. The compounds that have ionic bonding and hydrogen bonding will possess higher boiling point.

Answer to Problem 3.13P

In the given pair of compounds, ${\text{CH}}_{\text{2}}=\text{CHI}$ has higher boiling point.

Explanation of Solution

The given compounds are ${\text{CH}}_{\text{2}}=\text{CHCl}$ and ${\text{CH}}_{\text{2}}=\text{CHI}$.

Van der Waals forces exist in both the compounds due to the presence of $\text{C}-\text{C}$ and $\text{C}-\text{H}$ non polar bonds. Dipole-dipole interactions are also present due to the electronegativity difference between the carbon and halogen atoms. But the size of iodine is larger than that of chlorine. Therefore, it shows more polarizability. Hence, ${\text{CH}}_{\text{2}}=\text{CHI}$ has higher boiling point than ${\text{CH}}_{\text{2}}=\text{CHCl}$.

Conclusion

In the given pair of compounds, ${\text{CH}}_{\text{2}}=\text{CHI}$ has higher boiling point.