Entropy at 0 K

[melissa_dis4K]

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

[AnnaYan_1l]

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]

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: , 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]

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

[shaunajava2e]

are we assuming temperature is never below 0K?