## Reversible and Irreversible

isochoric/isometric: $\Delta V = 0$
isothermal: $\Delta T = 0$
isobaric: $\Delta P = 0$

Karina Kong 2H
Posts: 98
Joined: Thu Jul 25, 2019 12:16 am

### Reversible and Irreversible

I get that reversible reactions change infinitesimally, but why does it have greater changes in internal energy than irreversible reactions?

AArmellini_1I
Posts: 107
Joined: Fri Aug 09, 2019 12:15 am

### Re: Reversible and Irreversible

Because for infinitesimally small expansion, work must be done and equilibrium must be regained. This repeats over and over and this creates a decreasing curve where as irreversible expansion occurs immediately so work occurs instantly only once and equilibrium is only regained once (this creates a vertical drop then flattening out of the graph). Another way to see that reversible does more work than irreversible is the area under the curve for reversible is much greater than the area under the curve of the irreversible (or square-like shape).

Shail Avasthi 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

### Re: Reversible and Irreversible

AArmellini_1I wrote:Because for infinitesimally small expansion, work must be done and equilibrium must be regained. This repeats over and over and this creates a decreasing curve where as irreversible expansion occurs immediately so work occurs instantly only once and equilibrium is only regained once (this creates a vertical drop then flattening out of the graph). Another way to see that reversible does more work than irreversible is the area under the curve for reversible is much greater than the area under the curve of the irreversible (or square-like shape).

Here's an image that demonstrates this visually:

BritneyP- 2c
Posts: 101
Joined: Sat Sep 14, 2019 12:15 am

### Re: Reversible and Irreversible

For a given initial and final volume,more expansion work is done when the temperature is high than low. For a given volume and amount of gas- phase molecules, a higher temperature corresponds to a higher gas pressure, and so the expansion takes place against a stronger force and therefore has to do more work. More expansion work is also done if the V2 is much greater than V1

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