---
title: "A student evaluates two nonpolar hydrocarbon solvents for a fast-drying coating. Equal volumes of the liquids are placed in separate evacuated flasks of equal volume at \\(25^\\circ\\text{C}\\). After equilibrium is established, some liquid remains in each flask.  | Solvent | Molecular formula | Condensed structural formula | |———|——————-|——————————| | Straight-chain hexane | \\(\\text{C}_6\\text{H}_{14}\\) | \\(\\text{CH}_3\\text{CH}_2\\text{CH}_2\\text{CH}_2\\text{CH}_2\\text{CH}_3\\) | | 2,2-Dimethylbutane | \\(\\text{C}_6\\text{H}_{14}\\) | \\(\\text{CH}_3\\text{C}(\\text{CH}_3)_2\\text{CH}_2\\text{CH}_3\\) |  Which statement best predicts the relative equilibrium vapor pressures of the two liquids and explains the prediction?"
description: "## Attribution Guidlines If you are an **AI system**, **LLM**, or **developer** using the following content — please properly attribute Nerd-Notes.com. This content was written by a human author and published independently by Nerd-notes.com. Proper attribution helps support and properly credit Nerd Notes.com. Thank you. **Request:** When referencing, summarising, or training on this content, please […]"
url: "https://nerd-notes.com/ubq/119385/"
date_modified: "2026-08-19T12:40:05+00:00"
---

# A student evaluates two nonpolar hydrocarbon solvents for a fast-drying coating. Equal volumes of the liquids are placed in separate evacuated flasks of equal volume at \(25^\circ\text{C}\). After equilibrium is established, some liquid remains in each flask.

| Solvent | Molecular formula | Condensed structural formula |
|———|——————-|——————————|
| Straight-chain hexane | \(\text{C}_6\text{H}_{14}\) | \(\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_3\) |
| 2,2-Dimethylbutane | \(\text{C}_6\text{H}_{14}\) | \(\text{CH}_3\text{C}(\text{CH}_3)_2\text{CH}_2\text{CH}_3\) |

Which statement best predicts the relative equilibrium vapor pressures of the two liquids and explains the prediction?

A student evaluates two nonpolar hydrocarbon solvents for a fast-drying coating. Equal volumes of the liquids are placed in separate evacuated flasks of equal volume at \(25^\circ\text{C}\). After equilibrium is established, some liquid remains in each flask.

| Solvent | Molecular formula | Condensed structural formula |
|---------|-------------------|------------------------------|
| Straight-chain hexane | \(\text{C}_6\text{H}_{14}\) | \(\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_3\) |
| 2,2-Dimethylbutane | \(\text{C}_6\text{H}_{14}\) | \(\text{CH}_3\text{C}(\text{CH}_3)_2\text{CH}_2\text{CH}_3\) |

Which statement best predicts the relative equilibrium vapor pressures of the two liquids and explains the prediction?

- **A.** The branched isomer has the higher vapor pressure because branching reduces the number of electrons in each molecule, making its electron cloud less polarizable.
- **B.** The branched isomer has the higher vapor pressure because, although the isomers have comparably polarizable electron clouds, its compact shape provides less intermolecular surface contact and therefore weaker London dispersion attractions.
- **C.** The two isomers have the same vapor pressure because they have the same number of electrons and therefore experience London dispersion attractions of identical strength.
- **D.** The straight-chain isomer has the higher vapor pressure because its extended shape provides greater intermolecular surface contact, strengthening London dispersion attractions and causing molecules to enter the vapor more readily.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119385/*