## When to use this equation

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

sofiakavanaugh
Posts: 58
Joined: Thu Jul 13, 2017 3:00 am
Been upvoted: 1 time

### When to use this equation

Hi,

I was wondering in what specific situations we would need to use w=-pdeltaV versus other work equations

Does the temperature need to be constant?

Thanks!

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: When to use this equation

Hey! We use W=-pdeltaV for expansion work questions, typically regarding gases! I don't think temperature has to be constant in order to use this equation. Hope this helps!

Katie Blann 1E
Posts: 29
Joined: Tue Nov 15, 2016 3:00 am

### Re: When to use this equation

In the practice midterm we used this equation when the pressure was constant.

Erica Nagase 1H
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

### Re: When to use this equation

We use $w = -P\Delta V$ for irreversible conditions (constant P). We use $w = -nRTln\frac{V2}{V1}$ for reversible conditions (P is not constant).