## Reversible Expansion

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

Brandon Mo 4K
Posts: 70
Joined: Fri Sep 28, 2018 12:15 am

### Reversible Expansion

Could someone explain the derivation of work of reversible expansion? Also, what is the difference between reversible work and irreversible?

Posts: 60
Joined: Tue Nov 28, 2017 3:02 am

### Re: Reversible Expansion

A reversible expansion has a pressure that is constantly changing therefore the derivation of volume (the area under the curve) is needed to show a changing pressure. That is why the integral goes from one volume to another and why work for a reversible expansion is

w=-nRTln(V2/V1)

while a irreversible reaction has constant external pressure thus work is just simply:

w = -PdeltaV

Aria Soeprono 2F
Posts: 64
Joined: Fri Sep 28, 2018 12:27 am

### Re: Reversible Expansion

This might be an obvious question, but will a problem always tell you explicitly if it is reversible or irreversible?

michelle
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

### Re: Reversible Expansion

For an irreversible system, work is done under constant pressures and energy is lost as heat. For a reversible system, each energy lost by doing work will come back to the system as heat, and it is more efficient.