## work

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

Nahelly Alfaro-2C
Posts: 59
Joined: Wed Nov 15, 2017 3:04 am

### work

Just a verification for work equations:
We would use W=-Pdelta V when pressure is constant and W=-nRTln(V2/V1) when pressure is not constant?

Julia Go 2L
Posts: 60
Joined: Sun Sep 30, 2018 12:17 am
Been upvoted: 1 time

### Re: work

We need to calculate work when there is expansion work done. So firstly, there must be a change in volume.

Under constant pressure:
W=-Pdelta V

Under constant temperature: (isothermal, reversible)
W=-nRTln(V2/V1)

WilliamNguyen_4L
Posts: 65
Joined: Fri Sep 28, 2018 12:28 am

### Re: work

Yes, we use W=-pdeltav when the process is irreversible and pressure can be constant in that case. We use W=-nRTln(V2/V1) when the process is reversible and that's when pressure and volume can both not be constant. In a irreversible process if the pressure is not constant and volume is constant no work is done.