## Isobaric RXN

isochoric/isometric: $\Delta V = 0$
isothermal: $\Delta T = 0$
isobaric: $\Delta P = 0$

cbercik
Posts: 30
Joined: Wed Sep 21, 2016 3:00 pm

### Isobaric RXN

In an isobaric reaction where P is constant, why is w = PdV only significant for gases and not for solids/liquids?

Does this phase distinction affect what equation you use for w when calculating dU = q + w ?

Sarah Sharma 2J
Posts: 33
Joined: Fri Sep 29, 2017 7:05 am

### Re: Isobaric RXN

When P is constant, if dealing with an ideal gas the way to solve for entropy is Delta S= nCpln (V2/V1) Cp refers to the constant pressure which can be found by multiplying the ideal gas constant (R or 8.314J/K mol) by 5/2. So the equation when calculating for a reversible reaction will look like
Delta S= (n) (5/2) (R) ln (V2/V1). Hope this helps!