thermodynamics crystals

[206030797]

So I'm not a chemistry person, and we were talking in class about using crystals as location of a reaction or something, and I'm confused of the significance of crystals, as that wasn't explained or why we use crystals in thermodynamics.

[isabella1012]

recrystallization is when a solution of compounds can be dissolved in hot water and then cooled which is similar to one of the problems we did in class so maybe it has to do with that

[Leewon Koo 2K]

Another possibility is that we were talking about a perfect crystal structure that has been cooled to 0K, which would then have no entropy as the atoms would theoretically not move and there would be no residual positional entropy.

[Ethan Liang 1A]

My understanding was similar to Leewon's. We were talking about degeneracy and the crystal was brought up because it's an example of an ideal system that's perfectly ordered, meaning there's only one possible arrangement of the atoms. That would make W, or degeneracy, equal 1. And plugging that into the equation for entropy, you get 0 because ln1=0, which indicates that there is no entropy.

[Chloe Sy-Perez 1L]

This relates to the third law of thermodynamics about the behavior of systems as the temperature approaches absolute zero. So according to a crystal, it must be perfect to avoid disorder and the temperature must be 0 K or else there will be thermal motion which will also lead to disorder.