Chapter 14, Problem 54A

(a)

Interpretation Introduction

Interpretation:

The substance in the set with highest boiling point needs to be determined.

Concept Introduction:

The boiling points of various substances can be explained by considering intermolecular attractive forces which held the constituents together. Intermolecular attractive forces are highest for solids and lowest for gases. There is no force of attraction between gas molecules. Intermolecular attractive forces are moderate in liquid. In liquid substance, the boiling point depends on H-bonding.

Explanation of Solution

Among CaCl₂, H₂ and S₈, the boiling point of CaCl₂ is highest. Because CaCl₂ is an ionic compound, the particles CaCl₂ are held together tightly by strong electrostatic forces between opposite ions. Whereas H₂ is a gas molecule and S₈ is a molecular solid.

(b)

Interpretation Introduction

Interpretation:

The substance in the set with highest boiling point needs to be determined.

Concept Introduction:

The boiling points of various substances can be explained by considering intermolecular attractive forces which held the constituents together. Intermolecular attractive forces are highest for solids and lowest for gases. There is no force of attraction between gas molecules. Intermolecular attractive forces are moderate in liquid. In liquid substance, the boiling point depends on H-bonding.

Explanation of Solution

Among Ne, P₄ and KCl, the boiling point of KCl is highest. Because KCl is an ionic compound, the particles KCl are held together tightly by strong electrostatic forces between opposite ions. Whereas Ne is a gas molecule and P₄ is a molecular solid.

(c)

Interpretation Introduction

Interpretation:

The substance in the set with highest boiling point needs to be determined.

Concept Introduction:

The boiling points of various substances can be explained by considering intermolecular attractive forces which held the constituents together. Intermolecular attractive forces are highest for solids and lowest for gases. There is no force of attraction between gas molecules. Intermolecular attractive forces are moderate in liquid. In liquid substance, the boiling point depends on H-bonding.

Explanation of Solution

Among N₂, NH₃ and H₂, the boiling point of NH₃ is highest. Because NH₃molecules exhibited strong H-bonding with another NH₃ molecules and exists as an associated liquid. Whereas both N₂ and H₂ exist in a gaseous state.