---
title: "A student measures the equilibrium vapor pressure of four pure liquid 1-alkanols at \\(25\\ ^\\circ\\text{C}\\): methanol (\\(\\text{CH}_3\\text{OH}\\)), ethanol (\\(\\text{C}_2\\text{H}_5\\text{OH}\\)), 1-propanol (\\(\\text{C}_3\\text{H}_7\\text{OH}\\)), and 1-butanol (\\(\\text{C}_4\\text{H}_9\\text{OH}\\)). Which of the following lists the compounds in order of decreasing vapor pressure (greatest to least) at \\(25\\ ^\\circ\\text{C}\\) and provides the correct justification?"
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url: "https://nerd-notes.com/ubq/119630/"
date_modified: "2026-08-21T08:11:52+00:00"
---

# A student measures the equilibrium vapor pressure of four pure liquid 1-alkanols at \(25\ ^\circ\text{C}\): methanol (\(\text{CH}_3\text{OH}\)), ethanol (\(\text{C}_2\text{H}_5\text{OH}\)), 1-propanol (\(\text{C}_3\text{H}_7\text{OH}\)), and 1-butanol (\(\text{C}_4\text{H}_9\text{OH}\)). Which of the following lists the compounds in order of decreasing vapor pressure (greatest to least) at \(25\ ^\circ\text{C}\) and provides the correct justification?

A student measures the equilibrium vapor pressure of four pure liquid 1-alkanols at \(25\ ^\circ\text{C}\): methanol (\(\text{CH}_3\text{OH}\)), ethanol (\(\text{C}_2\text{H}_5\text{OH}\)), 1-propanol (\(\text{C}_3\text{H}_7\text{OH}\)), and 1-butanol (\(\text{C}_4\text{H}_9\text{OH}\)). Which of the following lists the compounds in order of decreasing vapor pressure (greatest to least) at \(25\ ^\circ\text{C}\) and provides the correct justification?

- **A.** \(\text{CH}_3\text{OH} > \text{C}_2\text{H}_5\text{OH} > \text{C}_3\text{H}_7\text{OH} > \text{C}_4\text{H}_9\text{OH}\), because \(\text{CH}_3\text{OH}\) has the smallest, least polarizable electron cloud, resulting in the weakest London dispersion forces and the easiest transition into the gas phase.
- **B.** \(\text{CH}_3\text{OH} > \text{C}_2\text{H}_5\text{OH} > \text{C}_3\text{H}_7\text{OH} > \text{C}_4\text{H}_9\text{OH}\), because shorter carbon chains produce stronger hydrogen bonds between molecules, which increases the average kinetic energy of the liquid.
- **C.** \(\text{C}_4\text{H}_9\text{OH} > \text{C}_3\text{H}_7\text{OH} > \text{C}_2\text{H}_5\text{OH} > \text{CH}_3\text{OH}\), because \(\text{C}_4\text{H}_9\text{OH}\) has the greatest molecular mass and therefore exerts the greatest gravitational force on the vapor phase.
- **D.** \(\text{C}_4\text{H}_9\text{OH} > \text{C}_3\text{H}_7\text{OH} > \text{C}_2\text{H}_5\text{OH} > \text{CH}_3\text{OH}\), because \(\text{C}_4\text{H}_9\text{OH}\) has the largest, most polarizable electron cloud, resulting in the strongest London dispersion forces.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119630/*