## Reversible Expansion

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

kennedyp
Posts: 56
Joined: Tue Nov 13, 2018 12:18 am

### Reversible Expansion

Why are systems at equilibrium reversible?

Ipsita Srinivas 1K
Posts: 50
Joined: Mon Jun 17, 2019 7:24 am

### Re: Reversible Expansion

My logic is that because both the backward and forward reactions are occurring at the same rate, there isn't really a direction or preference for the system. For irreversible reactions, there is a clear energy flow and even a small imbalance in pressure or temperature conditions isn't going to affect that. In a reversible reaction, it's almost as if the system is barely expanding (in the case of an isothermal gas expansion) and could just as easily compress with only a little increase in external pressure. There is a sort of weird dynamic balance happening, which is why you can say it's in equilibrium.