## q(REV)

$\Delta S = \frac{q_{rev}}{T}$

Clarisse Wikstrom 1H
Posts: 63
Joined: Fri Sep 29, 2017 7:05 am

### q(REV)

What exactly is q(REV) and how does it differ from q? Why is the (REV) significant, since when solving for deltaS we tend to replace it with deltaH anyways?

thanks!

Yutian Zhao -1J
Posts: 30
Joined: Fri Sep 29, 2017 7:05 am

### Re: q(REV)

same question!

Nicole Anisgard Parra 2H
Posts: 39
Joined: Sat Jul 22, 2017 3:01 am

### Re: q(REV)

qREV is just used to remind us that the reaction we are conducting has the heat transfer undertaken reversibly.

Vincent Tse 1K
Posts: 30
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 1 time

### Re: q(REV)

Nicole's right.

To add on to significance: Remember that during last friday's lecture Dr. Lavelle showed us two different processes--reversible and irreversible.
In reversible expansion, the temperature is constant, the volume increases, and the pressure decreases. The work done is the area under the curve (remember the PV diagram!), which can be calculated using the more annoying w = -nRTln(V2/V1) formula.
In irreversible expansion, the temperature ISNT constant, but the pressure is (while the volume increases). Work done is again the area under the curve, but since it's a straight line, you just find the area of the rectangle under the line (see the PV diagram). Basically, w = -PΔV.

So yeah, this is the "extra info" implied by the rev.