Re: [Phys-l] polytropic Sackur-Tetrode

[John Denker <jsd@av8n.com>]

On 01/20/2010 10:48 AM, Carl Mungan wrote:

> On page 255 he discusses this kind of thing, but 
> in addition to the electronic "weight" (partition 
> function), he points out you need to include a 
> rotational partition function.....

1) Hmmm, clearly my first attempt to derive the entropy
 of a polytropic gas was not correct.

2) I would hope that if the gas is really polytropic,
 the "weight" factor and everything else could be
 deduced from the observed gamma.  I'm hoping that
 only one new variable (gamma) needs to appear on 
 the RHS of the Sackur-Tetrode equation (as opposed
 to gamma, weight, and who-knows-what else).

 Or maybe I'm wrong about that, too.  Is it really
 possible to have two different polytropic gases
 with the same gamma but different entropy ... and
 therefore different heat capacity?  Doesn't that
 conflict with the notion of gamma as the ratio of
 specific heats?  I gotta go do the math on this
 one..........