## U for Reversible & Irreversible Expansion

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Yea Eun Lee 1H
Posts: 33
Joined: Fri Sep 29, 2017 7:06 am

### U for Reversible & Irreversible Expansion

According to the textbook, the "change in internal energy is the same regardless of the path taken between the same initial and final states"

So does that mean the change in internal energy would be the same regardless if the gas expanded reversibly or irreversibly? If so, why?

Haocheng Zhang 2A
Posts: 52
Joined: Fri Sep 29, 2017 7:04 am

### Re: U for Reversible & Irreversible Expansion

If both systems start and end with same initial and final internal energy, the change of internal energy should be the same, but the work done by the system(W) and the heat abosorbed by system(q) will be different in these two expansions.

Lisa Tang 1C
Posts: 62
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 2 times

### Re: U for Reversible & Irreversible Expansion

Because internal energy is a state function, it is only dependent on the current state of the system. So, the change of the internal energy is the same regardless of if the expansion was reversible or not.