## P delta(V) =delta(n)RT

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

Danny Nguyen 2H
Posts: 17
Joined: Fri Jul 22, 2016 3:00 am

### P delta(V) =delta(n)RT

When are we allowed to use this? under what circumstances do we use this? (refer to equation above)

stephanieyang_3F
Posts: 62
Joined: Wed Sep 21, 2016 2:55 pm

### Re: P delta(V) =delta(n)RT

You use w = -PdeltaV when pressure is constant. Prof. Lavelle used delta n RT to show that reactions at constant pressure can also do work when there is a change in the number of moles of gas.

Eunnie_Lee_3H
Posts: 35
Joined: Fri Jul 22, 2016 3:00 am
Been upvoted: 1 time

### Re: P delta(V) =delta(n)RT

I suppose you could use it any time you think you need to use P$\Delta$V but you don't have P and/or V. Some homework problems have it so that you would have to solve for work, but they don't give you P or $\Delta$V. Oftentimes, these homework problems will give you the mols of the element/compound in question, so in those cases you can use the mols they give you, the R which is constant, and the T (which in one certain homework problem in chapter 8 was assumed to be 298K due to everything having standard conditions).