Numéro
J. Phys. Colloques
Volume 48, Numéro C1, Mars 1987
VIIth Symposium on the Physics and Chemistry of Ice
Page(s) C1-687 - C1-688
DOI https://doi.org/10.1051/jphyscol:19871109
VIIth Symposium on the Physics and Chemistry of Ice

J. Phys. Colloques 48 (1987) C1-687-C1-688

DOI: 10.1051/jphyscol:19871109

FORMATION AND DECOMPOSITION OF ICY CLATHRATES

R. SMOLUCHOWSKI

University of Texas, Austin, TX 78712, U.S.A.


Abstract
Recent experimental studies (1) of the formation and decomposition of CO2 - clathrates, from and into H2O ice and CO2, seem to indicate an extremely low apparent activation energy (2) for these processes. A rough estimate of the probable energy associated with volume diffusion of CO2 molecule through hexagonal openings in the clathrate cage has been made. It suggests that these reactions occur primarily on surfaces of ice grains. The observed suppression of decomposition of clathrates by pressure (3) is in qualitative agreement with these conclusions. These and earlier results (4) indicate that porosity of cometary nuclei should play an important role in affecting the rate of escape of the entrapped molecules into the cometary coma.