---
title: "A student separates an equimolar liquid mixture of methanol, \\(\\text{CH}_3\\text{OH}\\) (normal boiling point \\(65\\ ^\\circ\\text{C}\\)), and water, \\(\\text{H}_2\\text{O}\\) (normal boiling point \\(100\\ ^\\circ\\text{C}\\)), by fractional distillation. Which of the following best identifies the substance that is enriched in the first fraction of distillate collected and provides the correct justification?"
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url: "https://nerd-notes.com/ubq/119638/"
date_modified: "2026-08-21T08:11:54+00:00"
---

# A student separates an equimolar liquid mixture of methanol, \(\text{CH}_3\text{OH}\) (normal boiling point \(65\ ^\circ\text{C}\)), and water, \(\text{H}_2\text{O}\) (normal boiling point \(100\ ^\circ\text{C}\)), by fractional distillation. Which of the following best identifies the substance that is enriched in the first fraction of distillate collected and provides the correct justification?

A student separates an equimolar liquid mixture of methanol, \(\text{CH}_3\text{OH}\) (normal boiling point \(65\ ^\circ\text{C}\)), and water, \(\text{H}_2\text{O}\) (normal boiling point \(100\ ^\circ\text{C}\)), by fractional distillation. Which of the following best identifies the substance that is enriched in the first fraction of distillate collected and provides the correct justification?

- **A.** \(\text{CH}_3\text{OH}\), because the covalent \(\text{C–H}\) and \(\text{O–H}\) bonds in \(\text{CH}_3\text{OH}\) require less energy to break than the covalent \(\text{O–H}\) bonds in \(\text{H}_2\text{O}\).
- **B.** \(\text{CH}_3\text{OH}\), because \(\text{CH}_3\text{OH}\) forms fewer hydrogen bonds per molecule than \(\text{H}_2\text{O}\), resulting in weaker overall intermolecular attractions and a higher vapor pressure at a given temperature.
- **C.** \(\text{H}_2\text{O}\), because \(\text{H}_2\text{O}\) has a smaller molar mass and fewer electrons than \(\text{CH}_3\text{OH}\), resulting in weaker London dispersion forces.
- **D.** \(\text{H}_2\text{O}\), because \(\text{H}_2\text{O}\) forms a more extensive hydrogen-bonding network than \(\text{CH}_3\text{OH}\), allowing it to absorb thermal energy and boil more rapidly.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119638/*