## Isothermal system

Tiffany Cao 1D
Posts: 94
Joined: Fri Sep 29, 2017 7:03 am
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### Isothermal system

Why delta S of the surroundings 0 in an isothermal, free expansion process?

Curtis Tam 1J
Posts: 105
Joined: Thu Jul 13, 2017 3:00 am

### Re: Isothermal system

Because the surroundings is basically a vacuum. The system is expanding but there is no heat transfer between the system and the surroundings so the surroundings basically remains unchanged.

Tatiana Hage 2E
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Joined: Thu Jul 27, 2017 3:00 am
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### Re: Isothermal system

Work = 0 in free expansion because there is no external pressure applied, so P=0 and therefore w=0. Since ΔU = 0, that means that q=0 as well, so no heat is transferred into the surroundings.

mayapartha_1D
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

### Re: Isothermal system

Hi Tiffany!

Because q=0 as there is no transfer of heat or change in temp (isothermal) there will be no change in entropy of the molecules.

704887365
Posts: 49
Joined: Sat Jul 22, 2017 3:00 am

### Re: Isothermal system

Work = 0 in free expansion because there is no external pressure applied, so P=0 and therefore w=0. Since ΔU = 0, that means that q=0 as well, so no heat is transferred into the surroundings.

Rishi Khettry 1L
Posts: 29
Joined: Fri Sep 29, 2017 7:05 am

### Re: Isothermal system

The term free expansion implies work is = 0 and in that case q would also be zero as the deltaU value needs to remain 0