---
title: "A student examines the standard molar entropy (\\(S^\\circ\\)) data at \\(298\\text{ K}\\) for four straight-chain gaseous hydrocarbons shown in the table below.  | Substance | Formula | Molar mass (\\(\\text{g/mol}\\)) | \\(S^\\circ\\) (\\(\\text{J}/(\\text{mol}\\cdot\\text{K})\\)) | |—|—|—|—| | Methane | \\(\\text{CH}_4\\text{(g)}\\) | \\(16.04\\) | \\(186.3\\) | | Ethane | \\(\\text{C}_2\\text{H}_6\\text{(g)}\\) | \\(30.07\\) | \\(229.6\\) | | Propane | \\(\\text{C}_3\\text{H}_8\\text{(g)}\\) | \\(44.10\\) | \\(270.3\\) | | Butane | \\(\\text{C}_4\\text{H}_{10}\\text{(g)}\\) | \\(58.12\\) | \\(310.2\\) |  Based on the data and principles of molecular structure and entropy, which of the following best explains why \\(\\text{C}_4\\text{H}_{10}\\text{(g)}\\) has a higher standard molar entropy than \\(\\text{C}_3\\text{H}_8\\text{(g)}\\)?"
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url: "https://nerd-notes.com/ubq/120345/"
date_modified: "2026-08-23T04:23:15+00:00"
---

# A student examines the standard molar entropy (\(S^\circ\)) data at \(298\text{ K}\) for four straight-chain gaseous hydrocarbons shown in the table below.

| Substance | Formula | Molar mass (\(\text{g/mol}\)) | \(S^\circ\) (\(\text{J}/(\text{mol}\cdot\text{K})\)) |
|—|—|—|—|
| Methane | \(\text{CH}_4\text{(g)}\) | \(16.04\) | \(186.3\) |
| Ethane | \(\text{C}_2\text{H}_6\text{(g)}\) | \(30.07\) | \(229.6\) |
| Propane | \(\text{C}_3\text{H}_8\text{(g)}\) | \(44.10\) | \(270.3\) |
| Butane | \(\text{C}_4\text{H}_{10}\text{(g)}\) | \(58.12\) | \(310.2\) |

Based on the data and principles of molecular structure and entropy, which of the following best explains why \(\text{C}_4\text{H}_{10}\text{(g)}\) has a higher standard molar entropy than \(\text{C}_3\text{H}_8\text{(g)}\)?

A student examines the standard molar entropy (\(S^\circ\)) data at \(298\text{ K}\) for four straight-chain gaseous hydrocarbons shown in the table below.

| Substance | Formula | Molar mass (\(\text{g/mol}\)) | \(S^\circ\) (\(\text{J}/(\text{mol}\cdot\text{K})\)) |
|---|---|---|---|
| Methane | \(\text{CH}_4\text{(g)}\) | \(16.04\) | \(186.3\) |
| Ethane | \(\text{C}_2\text{H}_6\text{(g)}\) | \(30.07\) | \(229.6\) |
| Propane | \(\text{C}_3\text{H}_8\text{(g)}\) | \(44.10\) | \(270.3\) |
| Butane | \(\text{C}_4\text{H}_{10}\text{(g)}\) | \(58.12\) | \(310.2\) |

Based on the data and principles of molecular structure and entropy, which of the following best explains why \(\text{C}_4\text{H}_{10}\text{(g)}\) has a higher standard molar entropy than \(\text{C}_3\text{H}_8\text{(g)}\)?

- **A.** \(\text{C}_4\text{H}_{10}\text{(g)}\) has more atoms and bonds per molecule, providing a greater number of accessible rotational and vibrational microstates for energy dispersal.
- **B.** \(\text{C}_4\text{H}_{10}\text{(g)}\) has stronger London dispersion forces between molecules, which increases the kinetic energy required to separate the gas particles.
- **C.** \(\text{C}_4\text{H}_{10}\text{(g)}\) molecules have a greater average molecular speed at \(298\text{ K}\), resulting in more frequent collisions and higher disorder.
- **D.** \(\text{C}_4\text{H}_{10}\text{(g)}\) has stronger \(\text{C}-\text{C}\) and \(\text{C}-\text{H}\) covalent bonds, requiring more energy to break the bonds during molecular motion.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/120345/*