The enthalpy of formation of gas-phase molecules and ions in binary systems formed by ytterbium, lutetium, and dysprosium trichlorides

The composition of the neutral and ionic saturated vapor components over sy stems of ytterbium, lutetium, and dysprosium trichlorides was studied in th e temperature range 940-1070 K by the Knudsen effusion method with mass spe ctrometric analysis of vaporization products under electron impact and ther mal ionization conditions. The equilibrium constants of various reactions w ere determined, and the enthalpies of formation of gas-phase molecules and ions, Delta(f)H degrees(298 K), kJ/mol, were calculated by the third law of thermodynamics to obtain -1617 +/- 20 for DyYbCl6, -1615 +/- 20 for DyLuCl 6, -1546 +/- 20 for LuYbCl6, -1547 +/- 20 for Yb2Cl6, -1194 +/- 10 for LuCl 4-, -1257 +/- 15 for DyCl4-, -1204 +/- 15 forYbCl(4)(-), -2067 +/- 15 for L u2Cl7-, -2235 +/- 20 for Dy2Cl7-, -2078 +/- 20 for Yb2Cl7-, -2078 +/- 25 fo r LuYbCl7-, -2165 +/- 25 for DyYbCl7-, -2158 +/- 35 for LuDyCl7-, -821 +/- 40 for AgDyCl4, -764 +/- 40 for AgYbCl4, -760 +/- 40 for AgLuCl4, -383 +/- 20 for AgCl2-, -1369 +/- 45 for AgDyCl5-, -1316 +/- 45 forAgYbCl(5)(-), and -1306 +/- 45 for AgLuCl5-. The enthalpy of sublimation of ytterbium trichl oride in the form, of dimeric molecules was found to be Delta(s)H degrees(Y b2Cl6, 298 K) = 373 +/- 20 kJ/mol.