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: (A)

Verified step by step guidance

1. Identify the two compounds: The compound on the left is cyclohexane, a cyclic alkane with the formula C6H12. The compound on the right is hexane, a straight-chain alkane with the formula C6H14.
2. Understand the factors affecting boiling points: Boiling points are influenced by molecular weight, molecular structure, and intermolecular forces. In general, stronger intermolecular forces result in higher boiling points.
3. Compare the molecular structures: Cyclohexane is a cyclic structure, which can lead to different packing and intermolecular interactions compared to the linear structure of hexane.
4. Consider the types of intermolecular forces: Both cyclohexane and hexane are nonpolar molecules, so the primary intermolecular force is London dispersion forces. The shape and surface area of the molecules can affect the strength of these forces.
5. Evaluate the boiling points based on structure: Cyclic structures like cyclohexane often have higher boiling points than their straight-chain counterparts due to more effective packing and stronger dispersion forces. Therefore, cyclohexane is expected to have a higher boiling point than hexane.