Measuring the force between air molecules

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SUMMARY

This discussion centers on measuring the attractive forces between air molecules, specifically comparing them to the forces observed in water molecules, such as hydrogen bonds. It highlights that air is a mixture of nitrogen, oxygen, argon, and other components, rather than a single "air molecule." The conversation also addresses the implications of attractive forces on the behavior of air during throttling, suggesting that cooling should occur if such forces exist, contrary to the behavior of ideal gases, which exhibit neither attractive nor repulsive forces.

PREREQUISITES
  • Understanding of molecular interactions, specifically hydrogen bonding.
  • Knowledge of gas laws and ideal gas behavior.
  • Familiarity with thermodynamics, particularly the concepts of throttling and cooling.
  • Basic principles of statistical mechanics related to molecular forces.
NEXT STEPS
  • Research methods for measuring intermolecular forces in gases.
  • Explore the principles of thermodynamics related to gas behavior during throttling.
  • Study the differences between real gases and ideal gases, focusing on Van der Waals forces.
  • Investigate experimental setups for observing molecular interactions in gas mixtures.
USEFUL FOR

Researchers in physical chemistry, physicists studying gas dynamics, and engineers involved in thermodynamic systems will benefit from this discussion.

tm007
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If there was an atractive force between air molecules, how could this be measured? The force should be small. In the range of the force between watermolecules (hydrogen bond).
 
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A previously unknown force between air molecules would show up as unexpected differences between the behavior of a volume of air and a volume of ideal gas.

(But do note that there’s no such thing as an “air molecule” - air is a mixture of nitrogen molecules, oxygen molecules, some stray argon atoms, and other odds and ends)
 
Nugatory said:
A previously unknown force between air molecules would show up as unexpected differences between the behavior of a volume of air and a volume of ideal gas.

(But do note that there’s no such thing as an “air molecule” - air is a mixture of nitrogen molecules, oxygen molecules, some stray argon atoms, and other odds and ends)
That´ s one thing.
Also if air molecules are attracted to each other then on throttling air, air ought to cool as those attractive forces are overcome.
For an ideal gas should have neither attractive nor repulsive forces between molecules, and should neither cool nor heat on throttling.
But how do you tell the difference between a gas having no attractive or repulsive forces vs. a gas having both attractive and repulsive forces but those balanced between each other?
How do you measure attractive forces in presence of repulsive forces?
 

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