PRACTICE:Which of the following pairs of molecules would have the highest boiling point?

• A. Compound on the left
• B. Compound on the right

Answer: (B)

Verified step by step guidance

1. Identify the two compounds: The compound on the left is cyclohexane, a cyclic alkane, and the compound on the right is acetone, a ketone.
2. Consider the types of intermolecular forces present in each compound. Cyclohexane, being a nonpolar molecule, primarily exhibits London dispersion forces. Acetone, on the other hand, is polar and can exhibit dipole-dipole interactions due to the presence of the carbonyl group.
3. Evaluate the strength of the intermolecular forces. Dipole-dipole interactions in acetone are generally stronger than the London dispersion forces in cyclohexane, which can lead to a higher boiling point.
4. Consider the molecular weight and structure. Cyclohexane has a higher molecular weight than acetone, which can contribute to higher boiling points due to increased London dispersion forces. However, the polarity and dipole-dipole interactions in acetone are significant factors.
5. Conclude by comparing the boiling points based on the analysis of intermolecular forces and molecular structure. The presence of stronger dipole-dipole interactions in acetone suggests it would have a higher boiling point compared to cyclohexane.