Charles' law and absolute zero

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SUMMARY

Charles' law states that the volume of a gas decreases as temperature decreases, ultimately predicting that at absolute zero, the volume of an ideal gas would be zero. This conclusion arises from the assumption that ideal gas particles are point particles with no volume, and their motion prevents them from occupying a single point. In reality, no gas is truly ideal, and gases cannot exist at absolute zero, as they would have liquefied or solidified. Therefore, while Charles' law provides a useful approximation for gases far from their vaporization point, it does not hold true at absolute zero.

PREREQUISITES
  • Understanding of Charles' law in thermodynamics
  • Familiarity with the concept of ideal gases
  • Basic knowledge of quantum mechanics and particle behavior
  • Awareness of phase transitions (liquid and solid states)
NEXT STEPS
  • Study the implications of the ideal gas law in real-world applications
  • Explore quantum mechanics principles related to particle behavior at low temperatures
  • Investigate the behavior of gases near their liquefaction and solidification points
  • Learn about the kinetic molecular theory and its relation to gas laws
USEFUL FOR

Students of physics, chemists, and anyone interested in thermodynamics and the behavior of gases under extreme conditions.

joeyjo100
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According to Charles' law, volume decreases with temperature. Extrapolating down towards absolute zero, and the volume of the gas will be zero.

How can this be possible? Surely any amount of gas will still have to take up some volume in space. Can multiple gas molecules really occupy zero volume?
 
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In practice no, probably not, although I'm not sure what weird quantum effects set in.

But when you have an 'ideal gas', you model the individual particles making up the gas as being point particles of zero volume which collide with each other. The overall volume of an ideal gas is therefore entirely due to the motion of the particles preventing them from all being squashed down to a single point, it doesn't depend on the size of the particles at all, and that is why at absolute zero, with no motion of the particles, the volume of an ideal gas is zero.

In practice no gas is 'ideal', so you're query is probably completely right, but the ideal gas law is still a very good approximation for the behavior of most gases when they are far from their vaporisation point. The size of each gas atom is negligible compared with space between adjacent atoms, so the volume of a gas at absolute zero (when the gap between atoms is zero) is also negligible.
 
There are no gases at absolute zero. Charles' law does not apply when the gas has liquified or solidified.
 

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