Which compound has the higher boiling point: CH3OH or CH3CH2CH3?

• A. CH3OH
• B. CH3CH2CH3

Answer: (A)

Verified step by step guidance

1. Identify the types of intermolecular forces present in each compound. For CH3OH (methanol), consider hydrogen bonding, dipole-dipole interactions, and London dispersion forces. For CH3CH2CH3 (propane), consider only London dispersion forces because it is a nonpolar molecule.
2. Recall that hydrogen bonding is a particularly strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. Methanol (CH3OH) contains an -OH group capable of hydrogen bonding.
3. Understand that stronger intermolecular forces require more energy (higher temperature) to overcome, which leads to a higher boiling point. Since CH3OH can hydrogen bond, it will have stronger intermolecular forces compared to CH3CH2CH3, which only has weak London dispersion forces.
4. Compare the molecular weights and structures: although CH3CH2CH3 has a slightly higher molecular weight, the presence of hydrogen bonding in CH3OH dominates the boiling point behavior.
5. Conclude that CH3OH has a higher boiling point than CH3CH2CH3 due to the presence of hydrogen bonding, which significantly increases the energy required to convert it from liquid to gas.