Crystallisation

[captain_kirk]

why is the crystallisation process an exothermic reaction? [other than the fact it obviously releases heat and causes a rise in temperature]
thanks

[m@tty]

Probably because it is essentially changing the compound from a liquid to a solid.

[kenhung123]

yea which can be explained by kinetic particle theory

[Mao]

This is better explained by a higher level concept [entropy], but it can be partially accounted for by the kinetic theory. Motion of liquid particles can be considered to be moving faster than vibrational motion of solid particles in a crystal. Thus, (l)->(s) transition is from a higher energy to lower energy, thus exothermic.