## when to use...?

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

connie 2C
Posts: 106
Joined: Thu Jul 11, 2019 12:17 am

### when to use...?

when do you use each equation and how do you know when to use it?

ALegala_2I
Posts: 102
Joined: Thu Jul 11, 2019 12:17 am

### Re: when to use...?

You use w=-PV when there is an expansion occurring at a constant external pressure. You use the other equation when there is a change in internal and external pressure for expansion work.

Elizabeth Harty 1A
Posts: 125
Joined: Sat Jul 20, 2019 12:16 am

### Re: when to use...?

You use the ln one when the pressure is not constant.

805097738
Posts: 180
Joined: Wed Sep 18, 2019 12:20 am

### Re: when to use...?

ALegala_2I wrote:You use w=-PV when there is an expansion occurring at a constant external pressure. You use the other equation when there is a change in internal and external pressure for expansion work.

what is the other equation?

Izzie Capra 2E
Posts: 103
Joined: Sat Sep 07, 2019 12:19 am

### Re: when to use...?

I think the other equation is w= -nRTln(V2/V1). Use this when work is being done at a non-constant pressure.