## Determining Expansion Work

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

Giselle Littleton 1F
Posts: 78
Joined: Wed Sep 18, 2019 12:20 am

### Determining Expansion Work

How can you tell whether a system does expansion work by just looking at the gas moles on both sides of the equation?

Isha_Maniyar_Dis2E
Posts: 110
Joined: Thu Jul 11, 2019 12:16 am

### Re: Determining Expansion Work

If there are more moles of gas on the product side than the reactant side, then the reaction did expansion work (expanded to more moles of gas). On the other hand, if there are fewer moles of gas on the product side, this means the system was compressed.

When calculating the number of moles of gas on either side, don't forget to take into account the COEFFICIENTS!!

Hope this helped!

MeeraBhagat
Posts: 95
Joined: Sat Aug 24, 2019 12:15 am

### Re: Determining Expansion Work

By comparing the moles of gas on the reactant and products sides of the balanced equation, you can tell if the system has done expansion work. If moles of R > moles of P, the system has compressed. If moles R < moles of P, the system has expanded. This is all assuming that this is an open system and volume can change.

Sally Qiu 2E
Posts: 105
Joined: Fri Aug 30, 2019 12:18 am

### Re: Determining Expansion Work

if there was a change in the number of moles, the system had done expansion work (if the volume can change)

CynthiaLy4F
Posts: 103
Joined: Sat Jul 20, 2019 12:16 am

### Re: Determining Expansion Work

You can tell when a system does expansion work if the number of moles of gas on the product side is greater than the number of moles on the reactant side.