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title: "A fixed quantity of gas is compressed to a high density inside a rigid container held at a constant temperature \\(T\\). Under these conditions, the measured pressure \\(P_{\\text{measured}}\\) is found to be lower than the pressure \\(P_{\\text{ideal}}\\) predicted by the ideal gas law \\(P = \\dfrac{nRT}{V}\\). Which of the following best explains why \\(P_{\\text{measured}}\\) is less than \\(P_{\\text{ideal}}\\) when attractive intermolecular forces are non-negligible?"
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url: "https://nerd-notes.com/ubq/116156/"
date_modified: "2026-08-03T11:46:03+00:00"
---

# A fixed quantity of gas is compressed to a high density inside a rigid container held at a constant temperature \(T\). Under these conditions, the measured pressure \(P_{\text{measured}}\) is found to be lower than the pressure \(P_{\text{ideal}}\) predicted by the ideal gas law \(P = \dfrac{nRT}{V}\). Which of the following best explains why \(P_{\text{measured}}\) is less than \(P_{\text{ideal}}\) when attractive intermolecular forces are non-negligible?

A fixed quantity of gas is compressed to a high density inside a rigid container held at a constant temperature \(T\). Under these conditions, the measured pressure \(P_{\text{measured}}\) is found to be lower than the pressure \(P_{\text{ideal}}\) predicted by the ideal gas law \(P = \dfrac{nRT}{V}\). Which of the following best explains why \(P_{\text{measured}}\) is less than \(P_{\text{ideal}}\) when attractive intermolecular forces are non-negligible?

- **A.** The attractive forces decrease the average translational kinetic energy of the gas molecules, resulting in a system with lower effective thermal energy than measured.
- **B.** Molecules approaching the container walls experience a net inward attractive force from bulk molecules behind them, reducing the momentum transferred per collision to the walls.
- **C.** The attractive forces increase the rate of collisions between gas molecules, which reduces the total number of impacts with the container walls per second.
- **D.** The attractive forces effectively increase the accessible volume of the container, which decreases the macroscopic collision frequency according to Boyle's law.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/116156/*