|MadSci Network: Physics|
Purification by selective crystallization is not well supported by theory. Thermodynamics can explain after observation but often not usefully predict before.
http://webmineral.com/data/Halite.shtml sodium chloride (halite); cubic
http://www.tms.org/pubs/journals/JOM/9902/Schulson-9902.html Ice, hexagonal The drug industry desperately funds research to predict crystal structure from molecular structure. After more than a decade of efforts not much has obtained. Crystal structure of simple ionic salts depends on radius ratios of the ions, J. Chem. Ed. 62(3) 215 (1985)
http://www.chem.ox.ac.uk/icl/heyes/structure_of_solids/Lecture3/Lec3.html It's complicated! http://www.lsbu.ac.uk/water/phase.html Water is tremendously studied. Water is not well understood.
http://www.chemguide.co.uk/physical/phaseeqia/saltsoln.html Even if we don't understand it we can observe it.
http://mysite.du.edu/~jcalvert/phys/phase.htm#Salt Wow. All that... and it's only water.
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