Question

Which has a higher boiling point ?

• A. Ethanol
• B. Propanol
• C. Methanol
• D. Methoxymethane

Hint:

When comparing boiling points of alcohols, consider both the molecular size (which affects London dispersion forces) and the presence of hydrogen bonding.

Answer 1

The Correct Option is B

To determine which compound has a higher boiling point, we must look at the molecular structure and intermolecular forces: - Ethanol (\( \text{CH}_3\text{CH}_2\text{OH} \)) and propanol (\( \text{CH}_3\text{CH}_2\text{CH}_2\text{OH} \)) are both alcohols, and they both experience hydrogen bonding. However, propanol has a longer carbon chain than ethanol, which increases the London dispersion forces (a type of van der Waals force) in propanol. - The boiling point increases as the size and length of the molecule increases, because larger molecules have more electrons, which lead to stronger dispersion forces.
Thus, propanol, having a larger molecular size and stronger dispersion forces, has a higher boiling point than ethanol. The correct answer is \( \text{Propanol} \).