Enthalpies of formation of the ions present in the saturated vapor over cesium chloride

The ionic composition of a vapor over cesium chloride was studied by the Kn udsen effusion method and by mass-spectrometry at 832-917 K. The equilibriu m constants for the ionic-molecular reactions were determined. Using the ca lculation procedure based on the third law of thermodynamics, enthalpies of formation Delta(f)H(o)(0 K) of the following gaseous ions were obtained (i n kJ/mol): 57 +/- 6 for Cs2Cl+, -626 +/- 6 For CsCl2-, -310 +/- 15 for Cs3C l2+, and -992 +/- 15 for Cs2Cl3-. The enthalpies of formation Delta(f)H(o)( 0 K) of the Cs4Cl3+ and Cs5Cl4+ ions were estimated at -670 +/- 40 and -105 0 +/- 50 kJ/mol, respectively.