---
title: "A student measures the pressure and volume of separate \\(1.00\\text{ mol}\\) samples of \\(\\text{CH}_4\\text{(g)}\\) and \\(\\text{CF}_4\\text{(g)}\\) in identical rigid \\(2.00\\text{ L}\\) containers at \\(200\\text{ K}\\). The student observes that for both gases, the compressibility ratio \\(\\dfrac{PV}{nRT} < 1.00\\), but the ratio for \\(\\text{CF}_4\\text{(g)}\\) is significantly lower than that for \\(\\text{CH}_4\\text{(g)}\\). Which of the following best explains why \\(\\text{CF}_4\\text{(g)}\\) exhibits a greater negative deviation from ideal gas behavior than \\(\\text{CH}_4\\text{(g)}\\) under these conditions?"
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url: "https://nerd-notes.com/ubq/119634/"
date_modified: "2026-08-21T08:11:53+00:00"
---

# A student measures the pressure and volume of separate \(1.00\text{ mol}\) samples of \(\text{CH}_4\text{(g)}\) and \(\text{CF}_4\text{(g)}\) in identical rigid \(2.00\text{ L}\) containers at \(200\text{ K}\). The student observes that for both gases, the compressibility ratio \(\dfrac{PV}{nRT} < 1.00\), but the ratio for \(\text{CF}_4\text{(g)}\) is significantly lower than that for \(\text{CH}_4\text{(g)}\). Which of the following best explains why \(\text{CF}_4\text{(g)}\) exhibits a greater negative deviation from ideal gas behavior than \(\text{CH}_4\text{(g)}\) under these conditions?

A student measures the pressure and volume of separate \(1.00\text{ mol}\) samples of \(\text{CH}_4\text{(g)}\) and \(\text{CF}_4\text{(g)}\) in identical rigid \(2.00\text{ L}\) containers at \(200\text{ K}\). The student observes that for both gases, the compressibility ratio \(\dfrac{PV}{nRT} < 1.00\), but the ratio for \(\text{CF}_4\text{(g)}\) is significantly lower than that for \(\text{CH}_4\text{(g)}\). Which of the following best explains why \(\text{CF}_4\text{(g)}\) exhibits a greater negative deviation from ideal gas behavior than \(\text{CH}_4\text{(g)}\) under these conditions?

- **A.** \(\text{CF}_4\) molecules occupy a larger finite volume than \(\text{CH}_4\) molecules, which decreases the available free volume in the container and lowers the measured pressure.
- **B.** \(\text{CF}_4\) molecules have a larger, more polarizable electron cloud than \(\text{CH}_4\) molecules, resulting in stronger London dispersion forces that reduce the force of collisions with the container walls.
- **C.** \(\text{CF}_4\) molecules possess polar \(\text{C}-\text{F}\) bonds that create strong dipole-dipole interactions, which draw the molecules toward one another and reduce the collision frequency.
- **D.** \(\text{CF}_4\) molecules have a greater molar mass than \(\text{CH}_4\) molecules, which gives them a lower average kinetic energy at \(200\text{ K}\) and reduces the momentum transferred per collision.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119634/*