## Change in Entropy in Surroundings [ENDORSED]

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

Mary Becerra 2D
Posts: 53
Joined: Fri Sep 29, 2017 7:06 am

### Change in Entropy in Surroundings

Why is it that when involved in an isothermal reversible expansion, the change in S of surroundings is equal to the opposite sign of the change in S of the system but when involved in an isothermal nonreversible free expansion, the change in S of surroundings is equal to zero?

Chem_Mod
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### Re: Change in Entropy in Surroundings  [ENDORSED]

In a free expansion no work is done: w = 0
Isothermal: Delta U = 0

Therefore, q = 0

Since no heat exchanged with the surroundings there is no entropy change in the surroundings.

Ask me this question in my Monday review as other students probably have the same question.

Yeyang Zu 2J
Posts: 58
Joined: Fri Sep 29, 2017 7:06 am

### Re: Change in Entropy in Surroundings

First, you can think of that everything is constant in the universe
Then, since Stotal=q(total)/T
Qtotal=zero
Stotal=0

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