Understanding Molecular Collisions in Gases

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SUMMARY

This discussion centers on the nature of molecular collisions in gases, emphasizing that molecules do not physically "touch" as macroscopic objects do. Instead, interactions occur through electromagnetic forces and electron orbital overlaps, which create repulsive forces at close distances. The analogy of "billiard balls in a container" is used to describe molecular behavior, despite the non-destructive interactions that define collisions. The conversation also raises questions about the implications of molecular geometry on gas viscosity.

PREREQUISITES
  • Understanding of physical gas dynamics
  • Familiarity with electromagnetic interactions
  • Knowledge of molecular orbital theory
  • Basic concepts of viscosity in fluids
NEXT STEPS
  • Research molecular dynamics simulations to visualize molecular interactions
  • Study the principles of kinetic theory of gases
  • Explore the effects of molecular geometry on gas viscosity
  • Learn about the role of dipole moments in molecular interactions
USEFUL FOR

Students and professionals in chemistry and physics, particularly those interested in molecular dynamics, gas behavior, and the fundamental principles of molecular interactions.

Aero51
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Hey, I'm not sure if this should be in the chemistry or physics section,. Hopefully it is in the right place. I have a question about molecular collisions: specifically, what actually happens when two molecules "collide". Perhaps a better question is: "what constitutes a molecular collision?". Since I have some background in physical gas dynamics and modern physics, I know that it is not possible for the two molecules to actually "touch" each other in the sense of two billiard balls colliding. On this subject, since molecules do not collide in the macroscopic sense, why do they behave as if they are, as stated earlier, billiard balls in a container? If anyone has good references or books please share those too!
 
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It is sufficient to have any sort of non-destructive interaction to make "billard balls in a container" a good model. If molecules come close to each other, their dipole moments can influence each other via the electromagnetic interaction. If they come even closer, their electron orbitals begin to overlap, which (usually) generates a repulsive force.
 
It is sufficient to have any sort of non-destructive interaction to make "billard balls in a container" a good model.

If this is true then what about gases with viscosity? Wouldn't that require one to know (or assume) something about the geometry of the molecules?
 

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