# Kinetic Theory and Thermophysical Properties

1. Feb 26, 2005

### Clausius2

Is there any way to derive the viscosity $$\mu$$ of an ideal gas from kinetic theory?

Also: Is there any way to derive the mass diffusitivity $$D$$ 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 $$D_i$$), or such magnitude is always referred to a gaseous mixture (i.e $$D_{ij}$$)?.

Some web link of bibliography would be greatly appreciated.

2. Feb 26, 2005

### Andrew Mason

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

3. Feb 26, 2005

### Bystander

See Hirschfelder, Curtiss, and Bird, Molecular Theory of Gases and Liquids for the theoretical treatments --- it'll be in the library.

4. Feb 28, 2005

### Clausius2

Thanks both of you.

AM, I am looking for a formulation, not only the historical background of the stuff.

5. Mar 2, 2005

### Clausius2

Thank you very much Bystander. I have found what I was looking for in Hirschfelder's book.

6. Mar 2, 2005

### Bystander

"The Green Monster" is the repository of all wisdom. You are welcome.

7. Mar 3, 2005

### Clausius2

"The Green and Heavy Monster" by the way.