| Topic: |
Science > Physics |
| User: |
"kevin" |
| Date: |
26 Sep 2006 09:26:25 PM |
| Object: |
entropy questions |
i have a few questions.
the first is related to Gibb's paradox. If there is two volumes of gas
separated in a box but each section of gas has a different temperature
(the only difference between the two), does the change in entropy still
equal 0? I know it doesnt equal zero, because the two sides are no
longer indistinguishable from one another. However, are they now treated
as two separate gases that undergo a volume change (through diffusion),
or only like two objects that undergo a heat exchange, or both?
Intuitively it seems that diffusion shouldnt matter because once the
temperatures equalize, the molecules are once again indistinguishable,
and therefore the heat flow only matters. But at the start, if you could
see the molecules, you could still see the faster ones diffusing with
the slower ones until they normalize, which would look like entropy
increasing. Does this matter, or does the change only depend on heat
exchange?
ill post the others later, i just ran out of time.
thanks for help
kevin
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| User: "kunzmilan" |
|
| Title: Re: entropy questions |
05 Oct 2006 09:21:43 AM |
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kevin,
nobody answered you, since you messed things together. You left aside
the effect of pressure on the system. If both parts are at the same
pressure, than the part with higher temperature has less molecules. It
can have higher specific entropy (are both gases identical ?) but the
product can be lower. If both part are separated by a wall, than there
exist only heat transfer, longer time is needed to get an equilibrium.
kunzmilan
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