Entropy at 0 K

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

melissa_dis4K
Posts: 106
Joined: Fri Sep 28, 2018 12:28 am

Entropy at 0 K

Can someone please explain why molecules do have entropy at 0 Kelvin and what that entropy is? Thank you!

AnnaYan_1l
Posts: 96
Joined: Fri Apr 06, 2018 11:05 am
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Re: Entropy at 0 K

Molecules that are perfectly ordered have no entropy at 0K (ex. CH4). For molecules that are not perfectly ordered, there is positional/residual entropy at 0K.

Luc Lorain 1L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

Re: Entropy at 0 K

AnnaYan_1l wrote:Molecules that are perfectly ordered have no entropy at 0K (ex. CH4). For molecules that are not perfectly ordered, there is positional/residual entropy at 0K.

Expanding on this, molecules that possess residual energy maintain some sort of entropy through positional, rather than kinetic or thermal-related entropy. This can occur from a molecule being asymmetrical in structure, or even just unorganized (not a perfect crystal structure), and derive entropy from their degeneracy. We have an equation to calculate this value: $S=k_{b}*ln(W)$, where W=degeneracy of the sample. This makes entropy easy to calculate for simple molecules smaller systems, but near to impossible for very complex molecules in very large systems.

MackenziePerillo-1L
Posts: 31
Joined: Fri Sep 28, 2018 12:19 am

Re: Entropy at 0 K

0K will additionally almost never appear in nature, therefore when referring to entropy at 0K, it is mostly used for conceptual limits.

shaunajava2e
Posts: 66
Joined: Fri Sep 28, 2018 12:26 am

Re: Entropy at 0 K

are we assuming temperature is never below 0K?

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