## When to use this equation

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

Moderators: Chem_Mod, Chem_Admin

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!

Aijun Zhang 1D
Posts: 53
Joined: Tue Oct 10, 2017 7:13 am

### Re: When to use this equation

When the pressure is constant, we use w = -Pext$\Delta V$

When temperature is constant (isothermal), we use w = -nRT ln (Vfinal/Vinitial)

Nha Dang 2I
Posts: 53
Joined: Fri Sep 29, 2017 7:07 am

### Re: When to use this equation

w = -nRT ln (Vfinal/Vinitial) is also used when the pressure is not kept at a constant.

snehabhargava
Posts: 52
Joined: Thu Jul 13, 2017 3:00 am

### Re: When to use this equation

That equation is used when the pressure is constant.

McKenna disc 1C
Posts: 60
Joined: Fri Sep 29, 2017 7:04 am

### Re: When to use this equation

Aijun Zhang 1D wrote:When the pressure is constant, we use w = -Pext$\Delta V$

When temperature is constant (isothermal), we use w = -nRT ln (Vfinal/Vinitial)

Are these the only two scenarios we'll likely be dealing with? Thanks!

Return to “Calculating Work of Expansion”

### Who is online

Users browsing this forum: No registered users and 1 guest