## Entropy of the System for irreversible expansions

$\Delta S = \frac{q_{rev}}{T}$

Amir Bayat
Posts: 115
Joined: Sat Sep 07, 2019 12:16 am

### Entropy of the System for irreversible expansions

What is the difference between the change in entropy for a reversible isothermal expansion vs an irreversible expansion? Are they exactly the same?

Cole Woulbroun 1J
Posts: 56
Joined: Thu Jul 25, 2019 12:16 am

### Re: Entropy of the System for irreversible expansions

Yes, they are the same because entropy is a state function.

Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

### Re: Entropy of the System for irreversible expansions

State functions means that the path doesn't matter so it is the same.

Amir Bayat
Posts: 115
Joined: Sat Sep 07, 2019 12:16 am

### Re: Entropy of the System for irreversible expansions

Also,

When is the change in internal energy zero for an irreversible expansion?

KaleenaJezycki_1I
Posts: 127
Joined: Sat Aug 17, 2019 12:18 am
Been upvoted: 2 times

### Re: Entropy of the System for irreversible expansions

Amir Bayat wrote:Also,

When is the change in internal energy zero for an irreversible expansion?

Internal energy is zero when Temperature is constant because there is no energy transfer if there is no change in temperature ( Internal energy measure the heat transfer) so there is none if temperature isn't changing. DeltaU= DeltaH-Deltan*R*T so if there is no temp change it all comes to be deltaU=0

Bryan Chen 1H
Posts: 58
Joined: Mon Jun 17, 2019 7:24 am

### Re: Entropy of the System for irreversible expansions

i believe they are the same, or at least you assume its always reversible

205389184
Posts: 100
Joined: Sat Sep 07, 2019 12:18 am

### Re: Entropy of the System for irreversible expansions

Since entropy is a state function, that means the path you take does not matter, so they will technically be the same.

Rida Ismail 2E
Posts: 139
Joined: Sat Sep 07, 2019 12:16 am

### Re: Entropy of the System for irreversible expansions

entropy is the same in both scenarios because entropy is a state function. It doesn't matter what path you take to get the change in entropy, it will be the same.