Free Expansion


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Emily Glaser 1F
Posts: 156
Joined: Thu Jul 27, 2017 3:01 am

Free Expansion

Postby Emily Glaser 1F » Mon Feb 12, 2018 2:45 pm

Are the values of Free Expansion the same as the values for an Isolated System in terms of deltaU, w, q, and deltaH?

All would be equal to zero?

Are free expansion and isolated system synonymous?

Julia Campbell 2F
Posts: 31
Joined: Sat Jul 22, 2017 3:00 am

Re: Free Expansion

Postby Julia Campbell 2F » Mon Feb 12, 2018 5:04 pm

They are conceptually a little different but yes, I think the variables you listed would all be zero for both.

Aya Shokair- Dis 2H
Posts: 58
Joined: Fri Sep 29, 2017 7:07 am

Re: Free Expansion

Postby Aya Shokair- Dis 2H » Mon Feb 12, 2018 5:40 pm

There is no work down on a free expansion. When you are looking at an isothermal free expansion, you know that delta U= 0.
So that means -w=q.
We just said that there is no work done on a free expansion, so both q & w would equal 0. Thus no heat transferred into the surroundings, so the entropy is unchanged. So the delta S= delta S tot

Aya Shokair- Dis 2H
Posts: 58
Joined: Fri Sep 29, 2017 7:07 am

Re: Free Expansion

Postby Aya Shokair- Dis 2H » Mon Feb 12, 2018 5:41 pm

^^ that is in an irreversible isothermal free expansion

Aya Shokair- Dis 2H
Posts: 58
Joined: Fri Sep 29, 2017 7:07 am

Re: Free Expansion

Postby Aya Shokair- Dis 2H » Mon Feb 12, 2018 5:44 pm

In an isothermal, reversible free expansion, delta S tot= 0 because it is an equilibrium.
So, delta S sys= -delta S surr


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