---
title: "A student evaluating a carbon-capture solvent system compares the following substances at \\(298\\text{ K}\\). The listed phase is used for each substance.  | Substance | Formula and phase | Molar mass (\\(\\text{g/mol}\\)) | |———–|——————-|——————————-| | Carbon dioxide | \\(\\text{CO}_2\\text{(g)}\\) | \\(44\\) | | Water | \\(\\text{H}_2\\text{O(l)}\\) | \\(18\\) | | Methanol | \\(\\text{CH}_3\\text{OH(l)}\\) | \\(32\\) | | Ethanol | \\(\\text{C}_2\\text{H}_5\\text{OH(l)}\\) | \\(46\\) |  Which of the following ranks the substances from greatest to least standard molar entropy, \\(S^\\circ\\), with the best justification?"
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url: "https://nerd-notes.com/ubq/119486/"
date_modified: "2026-08-19T12:40:42+00:00"
---

# A student evaluating a carbon-capture solvent system compares the following substances at \(298\text{ K}\). The listed phase is used for each substance.

| Substance | Formula and phase | Molar mass (\(\text{g/mol}\)) |
|———–|——————-|——————————-|
| Carbon dioxide | \(\text{CO}_2\text{(g)}\) | \(44\) |
| Water | \(\text{H}_2\text{O(l)}\) | \(18\) |
| Methanol | \(\text{CH}_3\text{OH(l)}\) | \(32\) |
| Ethanol | \(\text{C}_2\text{H}_5\text{OH(l)}\) | \(46\) |

Which of the following ranks the substances from greatest to least standard molar entropy, \(S^\circ\), with the best justification?

A student evaluating a carbon-capture solvent system compares the following substances at \(298\text{ K}\). The listed phase is used for each substance.

| Substance | Formula and phase | Molar mass (\(\text{g/mol}\)) |
|-----------|-------------------|-------------------------------|
| Carbon dioxide | \(\text{CO}_2\text{(g)}\) | \(44\) |
| Water | \(\text{H}_2\text{O(l)}\) | \(18\) |
| Methanol | \(\text{CH}_3\text{OH(l)}\) | \(32\) |
| Ethanol | \(\text{C}_2\text{H}_5\text{OH(l)}\) | \(46\) |

Which of the following ranks the substances from greatest to least standard molar entropy, \(S^\circ\), with the best justification?

- **A.** \(\text{CO}_2\text{(g)} > \text{CH}_3\text{OH(l)} > \text{C}_2\text{H}_5\text{OH(l)} > \text{H}_2\text{O(l)}\), because the gas has the greatest entropy and, among the two liquid alcohols, lower molar mass allows more accessible motion.
- **B.** \(\text{CO}_2\text{(g)} > \text{C}_2\text{H}_5\text{OH(l)} > \text{CH}_3\text{OH(l)} > \text{H}_2\text{O(l)}\), because a gas has greater positional freedom than a liquid, and molecular complexity generally increases the number of accessible microstates within a phase.
- **C.** \(\text{CO}_2\text{(g)} > \text{H}_2\text{O(l)} > \text{CH}_3\text{OH(l)} > \text{C}_2\text{H}_5\text{OH(l)}\), because a greater ability to form hydrogen bonds increases the number of accessible molecular arrangements in a liquid.
- **D.** \(\text{C}_2\text{H}_5\text{OH(l)} > \text{CH}_3\text{OH(l)} > \text{H}_2\text{O(l)} > \text{CO}_2\text{(g)}\), because intermolecular contacts in liquids provide more accessible arrangements than the free motion of particles in a gas.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119486/*