## Lecture notes , work eqn

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

Samira 2B
Posts: 38
Joined: Fri Sep 29, 2017 7:05 am

### Lecture notes , work eqn

This is from the lecture notes on Friday. Do we only use the work equation when the system is at equilibrium? Because that is when we use the derivative for the small changes in V that leads to the integral of the work eqn.

Abigail Yap 2K
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Re: Lecture notes , work eqn

Yes, I think we only use this equation when the system is at constant pressure (delta P = 0)!

Samira 2B
Posts: 38
Joined: Fri Sep 29, 2017 7:05 am

### Re: Lecture notes , work eqn

So, the system being at equilibrium means that it is a reversible process?

Sarah Maraach 2K
Posts: 31
Joined: Thu Jul 27, 2017 3:00 am

### Re: Lecture notes , work eqn

Yes exactly. Also, an irreversible reaction would be at equilibrium only after it has reacted, therefore it would not be able to react further.