Reversible vs Irreversible [ENDORSED]

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

Janice Xiao 1I
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

Reversible vs Irreversible

Can someone conceptually explain why a reversible pathway has more work done than an irreversible pathway?

Curtis Wong 2D
Posts: 62
Joined: Sat Jul 22, 2017 3:00 am

Re: Reversible vs Irreversible

A reversible pathway has more work done than an irreversible pathway mainly due to the fact that in a reversible process, it is pushing against that external pressure and tries to achieve the maximum expansion work possible. In an irreversible pathway some of the potential of the system to do work is lost because the external pressure will most likely be unable to push against the max external pressure at each stage of expansion

Clara Rehmann 1K
Posts: 53
Joined: Fri Sep 29, 2017 7:03 am

Re: Reversible vs Irreversible

A reversible process does more work because it is working against a constant pressure, meaning the pressure in the system changes slowly. An irreversible process, on the other hand, involves fast pressure changes that limit the system's ability to do work.

I found the graphs that Lavelle showed during class to be helpful - since work is the "area under the curve" of PΔV, if pressure changes gradually, there is a slope that allows for more area versus when the pressure changes suddenly, resulting in a smaller "box" with less area.

Garret G 2F
Posts: 24
Joined: Fri Sep 29, 2017 7:06 am

Re: Reversible vs Irreversible  [ENDORSED]

I really like to look at the curves of P vs V and take the area under them as total work done. This YouTube video explains reversible and irreversible processes really well: https://www.youtube.com/watch?v=LdM0DzlS3fQ