## constant pressure and constant volume

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

Jasmine Botello 2F
Posts: 67
Joined: Fri Sep 29, 2017 7:04 am

### constant pressure and constant volume

I am very confused because I am doing problems in which some say constant volume = 5/2R and others say constant pressure is 5/2R. Isn't one of these supposed to be 3/2R??

Jingyi Li 2C
Posts: 56
Joined: Fri Sep 29, 2017 7:06 am

### Re: constant pressure and constant volume

For ideal gases's specific heat capacity:
At constant volume:
monatomic gas: 3/2R
diatomic gas: 5/2R

At constant pressure (=Cv+R):
monatomic gas: 5/2R
diatomic gas: 7/2R

Nehal Banik
Posts: 64
Joined: Thu Jul 13, 2017 3:00 am

### Re: constant pressure and constant volume

It depends what the question is going to be asking, but if it asks for an ideal gas the CV is 3/2R and the CP is 5/2R, or at least that's what my TA told me.

Brigitte Phung 1F
Posts: 50
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 1 time

### Re: constant pressure and constant volume

For monatomic ideal gasses, at constant volume Cv = (3/2)R and at constant pressure Cp = (5/2)R.