Kinetic Theory and Thermophysical Properties

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Discussion Overview

The discussion revolves around deriving the viscosity and mass diffusivity of ideal gases from kinetic theory. Participants explore theoretical formulations, historical context, and the applicability of these properties to individual gases versus mixtures.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the derivation of viscosity (\mu) of an ideal gas from kinetic theory.
  • There is a question regarding the derivation of mass diffusivity (D) of an ideal gas from kinetic theory.
  • Participants discuss whether mass diffusivity can be defined for an individual gas (D_i) or if it is always related to a mixture (D_{ij}).
  • One participant references Maxwell's historical contributions to the derivation of gas viscosity from kinetic theory, noting the role of momentum transfer between molecules.
  • Another participant suggests consulting Hirschfelder, Curtiss, and Bird's "Molecular Theory of Gases and Liquids" for theoretical treatments related to the topic.

Areas of Agreement / Disagreement

Participants express interest in the derivations and historical context, but there is no consensus on the specific formulations or definitions of mass diffusivity for individual gases versus mixtures.

Contextual Notes

The discussion includes references to historical derivations and theoretical texts, but lacks specific mathematical formulations or detailed derivations of the properties in question.

Clausius2
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Is there any way to derive the viscosity [tex]\mu[/tex] of an ideal gas from kinetic theory?

Also: Is there any way to derive the mass diffusitivity [tex]D[/tex] of an ideal gas from kinetic theory?.

Another one: does it make sense to talk about the mass diffusivity of an individual gas (for instance [tex]D_i[/tex]), or such magnitude is always referred to a gaseous mixture (i.e [tex]D_{ij}[/tex])?.

Some web link of bibliography would be greatly appreciated.
 
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Clausius2 said:
Is there any way to derive the viscosity [tex]\mu[/tex] of an ideal gas from kinetic theory?

Some web link of bibliography would be greatly appreciated.
Apparently there is. Viscosity of a gas is interesting. It is entirely different than viscosity of liquids. Seems Maxwell was the first to derive it from kinetic theory. See: http://www.math.umd.edu/~lvrmr/History/Foundations.html

"In a gas, viscous force originates not in the forces between neighboring molecules but in the transfer of momentum that occurs when a molecule from a faster-moving stream wanders over to a slower-moving stream and collides with a molecule there. The rate of momentum transfer increases with the average molecular speed, so (1) the viscosity increases with temperature."

AM
 
See Hirschfelder, Curtiss, and Bird, Molecular Theory of Gases and Liquids for the theoretical treatments --- it'll be in the library.
 
Andrew Mason said:
Apparently there is. Viscosity of a gas is interesting. It is entirely different than viscosity of liquids. Seems Maxwell was the first to derive it from kinetic theory. See: http://www.math.umd.edu/~lvrmr/History/Foundations.html

"In a gas, viscous force originates not in the forces between neighboring molecules but in the transfer of momentum that occurs when a molecule from a faster-moving stream wanders over to a slower-moving stream and collides with a molecule there. The rate of momentum transfer increases with the average molecular speed, so (1) the viscosity increases with temperature."

AM

Thanks both of you.

AM, I am looking for a formulation, not only the historical background of the stuff.
 
Bystander said:
See Hirschfelder, Curtiss, and Bird, Molecular Theory of Gases and Liquids for the theoretical treatments --- it'll be in the library.

Thank you very much Bystander. I have found what I was looking for in Hirschfelder's book.
 
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"The Green and Heavy Monster" by the way. :smile:
 

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