THE COMPOSITION OF SATURATED VAPOR OVER DYSPROSIUM TRICHLORIDE - THE THERMODYNAMIC CHARACTERISTICS OF THE IONIC AND NEUTRAL COMPONENTS

The composition of the neutral and ionic components of saturated vapor over dysprosium trichloride are investigated in the temperature range of 840-1057 K by the Knudsen effusion method with mass-spectroscopic recording of ionization products. The associate molecules of Dy2Cl6, D y3Cl9, and Dy4Cl12 and Cl-, DyCl4-, Dy2Cl7-, Dy+, and DyCl+ ions have been detected in saturated vapor for the first time. The enthalpies of sublimation of Delta(s)H(0)(DyCl3, 298 K) = 272 +/- 5 and Delta(s)H(0 )(Dy2Cl6, 298 K) = 332 +/- 10 and the enthalpies of formation of molec ules of Delta(f)H(0)(DyCl3, g, 298 K) = -726 +/- 5 and Delta(f)H(0)(Dy 2Cl6, g, 298 K) = -1664 +/- 12 kJ/mol are determined using the procedu res of the second and third laws of thermodynamics. The enthalpies of formation of ions of Delta(f)H(0)(DyCl4-, g, 298 K) = -1204 +/- 15 and Delta(f)H(0)(Dy2Cl7-, g, 298 K) = -2164 +/- 30 kJ/mol were calculated from the enthalpies of ion-molecular equilibriums DyCl4- = Cl- + [DyC l3], Delta(r)H(0)(298 K) = -28 +/- 10 kJ/mol, Dy2Cl7- = DyCl4- + [DyCl 3], Delta(r)H(0)(298 K) = -38 +/- 20 kJ/mol.