Thursday, March 25, 2010

C1500 in the preparatory problem of IChO 2010

Problem 3 in the preparatory problem of IChO 2010 asks the buoyancy property of icosahedral buckyballs. It would be interesting but time consuming to construct all beaded models for the buckyballs with I symmetry less than 1500 carbon atoms. Right now, the largest buckyball belonging to this family I made is C320.

This problem claims that the giant buckyball are molecular balloons.
To me, the Archimedean principle of buoyancy is a macroscopic law due to the pressure course-graining over large amount of tiny collisions. Nano-particles such as C1500 have sizes less than the mean free path of the gas at 1 bar. So these nano-particles should simply follow the Boltzmann distribution, P ~ exp(-mgh/kT), based on their potential energy, mgh, at the height.

1 comment:

Bih-Yaw Jin said...

The students of Taiwan's IChO team told me last week that the minimum radius they obtained for molecular balloon is about several microns which is large enough for a well-defined concept of buoyancy.