## Reversible and Irreversible Processes

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

Stephanie_Thai_2C
Posts: 10
Joined: Fri Jul 22, 2016 3:00 am

### Reversible and Irreversible Processes

Can someone clarify the importance of reversible processes in chemistry and work? I understand the difference of reversible and irreversible processes in that the former can be reversed by a infinitely small change in a variable but I can't see the connection to its significance in work.

Esther_Choe_1K
Posts: 11
Joined: Fri Jun 17, 2016 11:28 am

### Re: Reversible and Irreversible Processes

I have the same question specifically regarding why the work a system can do is greatest in a reversible process..

Aishwarya_Natarajan_2F
Posts: 11
Joined: Mon Jul 11, 2016 3:00 am

### Re: Reversible and Irreversible Processes

Reversible processes can be reversed by an infinitely small change in a variable while an irreversible process doesn't. One of the applications of these two is taking the example of a piston, when can reverse directions in a reversible process with small changes in pressure, and this doesn't happen in the case of a reversible process.

If we look at Boyle's law, as volume increases, pressure decreases when the gas expands. As a result, if we want to achieve a reversible expansion, we have to reduce external pressure as well because the internal pressure of the gas is falling as it expands. There is a box on pg 265 explaining the derivations of the equation, but this is the idea behind it.

In a reversible expansion, external pressure is reduced to match internal pressure. In an irreversible expansion, we don't change external pressure and because of this some of the potential of the system to do work is lost with the opposing pressure externally. In reversible expansions, since internal pressure = external pressure, the system has the potential for the maximum amount of work. Example 8.2 does a pretty good job illustrating how to use the two equations.