MASS SPECTROMETRY OF VAPORS OVER PBCL2 + ACL MIXTURES (A = NA K RB OR CS) .I. THERMODYNAMIC STUDIES

A mass spectrometric study of the vaporization properties of (mainly molten) PbCl2 + ACl mixtures has been made. The complex molecules APbCl3 have been identified in the vapor phase and their enthalpies and free energies of formation, from gaseous ACl and PbCl2 molecules, have been measured over temperature and pressure ranges of 740-910°K and ca. 10-7-10-3 atm, respectively. For these complex molecules the enthalpies of formation are in the range of -36 to -41 kcal/mol. The corresponding entropies of formation are in the range of -19 to -20 eu. A structure for the complex molecules has been suggested on the basis of simple coulombic calculations.