Multiple Choice
Which of the following best explains how the molecular structure of a material influences its physical properties?
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13. Liquids, Solids & Intermolecular Forces
Intermolecular Forces and Physical Properties
Multiple Choice
Which of the following molecules would be expected to have the lowest boiling point?
A
H2O
B
HF
C
NH3
D
CH4
Verified step by step guidance1
Step 1: Understand that boiling point is influenced by the strength of intermolecular forces present in the substance. Stronger intermolecular forces generally lead to higher boiling points.
Step 2: Identify the types of intermolecular forces in each molecule: H2O, HF, and NH3 all exhibit hydrogen bonding, which is a strong type of dipole-dipole interaction. CH4, on the other hand, is nonpolar and only exhibits weak London dispersion forces.
Step 3: Recognize that hydrogen bonding significantly increases boiling points because it requires more energy to break these interactions during the phase change from liquid to gas.
Step 4: Compare the molecules: H2O, HF, and NH3 have hydrogen bonding and thus higher boiling points, while CH4 lacks hydrogen bonding and has only weak dispersion forces, resulting in a much lower boiling point.
Step 5: Conclude that CH4 would be expected to have the lowest boiling point among the given molecules due to its weak intermolecular forces.
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