Thermodynamic properties of ytterbium chlorides

From the results of saturated vapor pressure measurements of liquid and solid ytterbium di- and trichloride samples, from the equilibrium constants of the gas reactions BaCl + Yb = Ba + YbCl and 2BaCl + Yb = 2Ba +YbCl2, and from the appearance and ionization potentials of the ytterbium chlorides, we calculate the enthalpies of atomization for ytterbium mono-, di, and trichlorides: Delta(at)H(298)(0) (YbCl) = 363.8 +/- 1.5 kJ/mol, Delta(at)H(298)(0) (YbCl2) = 850.7 +/- 2.8 kJ/mol, and Delta(at)H(298)(0) (YbCl3) = 1166.5 +/- 4.3 kJ/mol. For the same molecules, the enthalpies of formation are calculated: Delta(f)H(298)(0) (YbCl, gas) = -89.9 +/- 1.5 kJ/mol, Delta(f)H(298)(0) (YbCl2, gas) -455.6 +/- 3.2 kJ/mol, and Delta(f)H(298)(0) (YbCl3, gas) = -651.1 +/- 5.0 kJ/mol. New values of the thermodynamic functions for condensed YbCl3 and YbCl2 and for gaseous ytterbium mono-, di-, and trichlorides were used in all the calculations. The ionization and appearance potentials for the ions forming upon the ionization of ytterbium trichloride are determined by the electronic impact method.