At a given temperature, the compressibility factor Z of a real gas is found to be less than 1. What does this suggest about the gas under these conditions?

Repulsive forces dominate, and the gas is harder to compress than ideal

The gas obeys the ideal gas law exactly

The molar volume of the gas is larger than predicted by the ideal gas law

At a given temperature, the…

Answer: Attractive forces dominate, making the gas more compressible than ideal.

A Repulsive forces dominate, and the gas is harder to compress than ideal
B Attractive forces dominate, making the gas more compressible than ideal
C The gas obeys the ideal gas law exactly
D The molar volume of the gas is larger than predicted by the ideal gas law

Correct answer: B. Attractive forces dominate, making the gas more compressible than ideal

Explanation: Z less than 1 means the real volume is smaller than the ideal volume, showing that attractive forces pull molecules closer, making the gas more compressible than predicted.

Graph of pressure versus volume for a fixed amount of gas at constant temperature: the curve falls steeply then flattens, a hyperbola showing pressure inversely proportional to volume.

Boyle's law: at constant temperature the pressure of a fixed mass of gas is inversely proportional to its volume (P ∝ 1/V), so the P–V plot is a hyperbola — halving the volume doubles the pressure. Image: Reginaprice2013, CC BY-SA 3.0, via Wikimedia Commons.

Concept context

Discover why gases expand to fill any container while liquids flow and solids hold their shape. Master the gas laws, the ideal gas equation, and the reasons real gases deviate from ideal behavior.

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At a given temperature, the compressibility factor Z of a real gas is found to be less than 1. What does this suggest about the gas under these conditions?

Concept context

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