Chapter 14, Problem 59A

(a)

Interpretation Introduction

Interpretation: The type of intermolecular forces acting in the liquid state for nitrogen gas needs to be explained.

Concept Introduction: The intermolecular forces are the forces between molecules of substances. These intermolecular forces depend of polarity of the molecules. There are different types of intermolecular forces. Some of them are listed below:

• Dispersion force
• Hydrogen bond
• Dipole-dipole interaction
• Dipole-ion interaction

Answer to Problem 59A

Liquid ${\text{N}}_{\text{2}}$ molecules have dispersion forces.

Explanation of Solution

The ${\text{N}}_{\text{2}}$ molecules are non-polar molecules. They do not have polarity as both atoms are same and bonded with triple covalent bond. Therefore there will be weakest dispersion forces between molecules.

Because of these weak dispersion forces, ${\text{N}}_{\text{2}}$ gas can be liquefied easily.

(b)

Interpretation Introduction

Interpretation: The type of intermolecular forces acting in the liquid state of ${\text{NH}}_{\text{3}}$ needs to be determined.

Concept Introduction: The intermolecular forces are the forces between molecules of substances. These intermolecular forces depend of polarity of the molecules. There are different types of intermolecular forces. Some of them are listed below:

• Dispersion force
• Hydrogen bond
• Dipole-dipole interaction
• Dipole-ion interaction

Answer to Problem 59A

Liquid ${\text{NH}}_{\text{3}}$ molecules have hydrogen bonds.

Explanation of Solution

The ${\text{NH}}_{\text{3}}$ molecules are polar molecules. Each molecule contains electronegative N atom and H atom which can form hydrogen bond with other N atoms of ${\text{NH}}_{\text{3}}$ molecule. Therefore liquid ${\text{NH}}_{\text{3}}$ molecules have hydrogen bonds between molecules.

(c)

Interpretation Introduction

Interpretation: The types of intermolecular forces acting in the liquid state for helium needs to be determined.

Concept Introduction: The intermolecular forces are the forces between molecules of substances. These intermolecular forces depend of polarity of the molecules. There are different types of intermolecular forces. Some of them are listed below:

• Dispersion force
• Hydrogen bond
• Dipole-dipole interaction
• Dipole-ion interaction

Answer to Problem 59A

Liquid $\text{He}$ atoms have dispersion forces.

Explanation of Solution

The $\text{He}$ atoms are non-polar, monoatomic elements as it is a Noble gas and cannot interact or form chemical bond with each other to form molecules. The monoatomic He elements have only weakest dispersion forces between atoms due to their non-polar nature.

(d)

Interpretation Introduction

Interpretation: The types of intermolecular forces acting in the liquid state of ${\text{CO}}_{\text{2}}$ needs to be determined.

Concept Introduction: The intermolecular forces are the forces between molecules of substances. These intermolecular forces depend of polarity of the molecules. There are different types of intermolecular forces. Some of them are listed below:

• Dispersion force
• Hydrogen bond
• Dipole-dipole interaction
• Dipole-ion interaction

Answer to Problem 59A

Liquid ${\text{CO}}_{\text{2}}$ has dispersion forces.

Explanation of Solution

The ${\text{CO}}_{\text{2}}$ molecule has two polar C=O bonds but the molecule is non-polar due to symmetrical structure. Thus the non-polar molecules of ${\text{CO}}_{\text{2}}$ can only have weak dispersion forces.