## residual entropy

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

Jane Burgan 1C
Posts: 73
Joined: Fri Sep 28, 2018 12:15 am

### residual entropy

Can someone explain what residual entropy is and why it's important?

Posts: 60
Joined: Fri Sep 28, 2018 12:27 am

### Re: residual entropy

Residual entropy has to do with the placement of certain atoms within a molecule. For example, a molecule like CH3Cl would have residual entropy because there are four different places (degeneracy) where you can put the Cl in the tetrahedral shape. A molecule like O2 on the other hand only has one configuration, so there is no residual entropy.

Patrick Cai 1L
Posts: 93
Joined: Fri Sep 28, 2018 12:25 am

### Re: residual entropy

Residual entropy is mostly considered in situations where all types of entropy is removed, such as the case of cooling molecules to almost 0 K. Under these conditions, the particles are considered motionless and thus we ignore aspects like entropy associated with gaseous phase particles, etc.

Cody Do 2F
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

### Re: residual entropy

In class today, we spoke about residual entropy mostly in terms of absolute cooling (where the temperature is 0 K, or rather, as close to 0 K as we can presently reach). In molecules where degeneracy > 1 exist, even in the event that 0 K were reached, some level of residual entropy would exist due to the possible arrangement of atoms.