Complex Formation due to Polarization. I. The System Krypton and Hydrogen Chloride

Abstract

Rare gases form compounds of a loose complex nature such as hydrates, solvates or mercury complexes. Such molecular aggregates contain a molecule of permanent dipole moment or an excited atom or molecule of dipole character as the other reaction partner besides the rare gas. The forces holding the complex molecule are the attraction between the permanent dipole and the dipole induced in the rare gas molecule due to its polarizability. Five lines of evidence are cited which indicate the formation of such complex molecules: (1) Band spectra of complex HgA and HgKr are known. (2) Rare gas hydrates have been described. (3) Isoelectronic systems similar to the rare gases have proton affinity. (4) Rare gas hydride ions have been found in the mass-spectrograph. (5) The P-V-T relation of gaseous mixtures show that interaction between the unlike molecules exists. The second Virial coefficient is determined experimentally for Kr–HCl mixtures as a function of composition and it is shown that interaction exists between the rare gas atom Kr and the permanent dipole HCl.