## When to Use Different Formulas for Work

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

Michelle_Nguyen_3F
Posts: 40
Joined: Wed Sep 21, 2016 2:59 pm

### When to Use Different Formulas for Work

In which situations/under which conditions would we use $w = - P\Delta V$ or $w = -nRTln\frac{V_{2}}{V_{1}}$?

Jenna_Hakel_2A
Posts: 34
Joined: Fri Jul 15, 2016 3:00 am

### Re: When to Use Different Formulas for Work

We use w=-PdeltaV when the pressure against which the gas is expanding is constant. However, we use the second equation when the pressure is variable, such as when the expansion is reversible.

Derek Lee 2K
Posts: 30
Joined: Sat Jul 09, 2016 3:00 am

### Re: When to Use Different Formulas for Work

It basically boils down to irreversible reactions which is the first equation and reversible ones which is the second.