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Re: DW/DW Summary



At 10:09 PM 01-11-99 -0500, someone wrote:
Vehemently NO for your 7) and 8).

Margaret!!! Help!!! The other boys on the playground are being raucous, I
wish there were more girls here. They are nicer -- and better looking too.

In the light of morning, I see that I have experienced a major mental
lapse: what I wrote in 7) and 8) is faulty, But I don't yet see where the
error is. I will have to think more on this and on Bob's statements below,
which, I believe, are faulty as well. But I can't think with all this
commotion.

I _am_ pleased that points 1 through 6 (which I fervently stand behind) are
accepted -- at least in part. This has been a several year effort! (:-)

Jim

dQ is different for different paths between the same two states.

dQ =TdS ONLY for a reversible path between the two given states.

dS =dQ/T (reversible process) is path independent;

dQ (even for reversible processes {where dQ=Tds} ) is path dependent.

Bob

> . . .
> 7) The only way to calculate DQ for the irreversible process is to
choose a
> reversible process with the same end states as the irreversible one,
> determine the end point entropy of that process and then calculate
DQ=TdS.
>
> 8) In some cases dS might be determined from a carefully chosen DQ of
the
> reversible process, but that would be the same DQ for the irreversible

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen