Re: [Phys-l] third law of thermo

[Arnulfo Castellanos Moreno <acastell@correo.fisica.uson.mx>]

Hi!

The third law of thermodynamics should not be written like the entropy
going to zero when the temperature goes to zero.

It shuld be written as the changes of the entropy goes to zero ...

There are a lot of examples to show that entropy goes to a constant to
take into account that disorder is present but frozen.


Arnulfo Castellanos Moreno



El mié, 17-02-2010 a las 10:22 -0500, Carl Mungan escribió:
> I recognize that there are many different views on the 3rd law. 
> Specifically S does not always go to zero as T->0. However, I thought 
> one could safely say it approaches a constant (often called the 
> residual entropy) with zero slope, ie dS/dT->0 as T->0 (technically 
> it's a partial derivative with N,V,B,etc held constant). Apparently I 
> must be wrong about that however. Consider an ideal fermi gas. It has 
> C linearly proportional to T at low T. Then dS/dT=C/T=nonzero 
> constant as T->0.
>
> Do others agree with my analysis or am I missing some key idea? -Carl