Cristais dançantes

Synopsis: molecules can interact in different ways. The interactions can be intermolecular or intramolecular (the latter are called bonds), and can exist mainly in 4 types: permanent dipole, induced dipole (or Van der Waals), hydrogen bonding and ionic bonding. The main purpose of this demonstration is precisely to illustrate the interactions between the molecules of naphthalene with each other, but also with those of water and acetone, in order to facilitate the understanding of this phenomenon so curious. In the demonstration, naphthalene crystals form in an acetone solution and "dance," that is, they are in motion, although no stirring has been made in the system where naphthalene is present. At this point, it is possible to perceive the interactions there. This experiment can be used for discussion of intermolecular forces, but also for the study of: liquid properties, surface tension, crystallization and solubility.
Source: UFMG - Pontociência, Q2Acoltec2009 Quimica.
URL: http://www.publishing.co.uk/experiments-internet.php?experiment=385&CRISTAIS+DANCANTES#top