Evaporation behaviour of lanthanum trihalides

The evaporation of LaCl3, LaBr3 and LaI3 was investigated in closed tubes u nder argon atmosphere and correlated with data in the literature. The entha lpies and entropies of evaporation were derived from the temperature functi ons of pressure: Delta H degrees(v, LaCl3, T) = 48,5 +/- 2 kcal/mol, Delta S degrees(v, LaCl 3, T) = 22,0 +/- 3 cal/K.mol Delta H degrees(v, LaBr3, T) = 48,0 +/- 2 kcal/mol, Delta S degrees(v, LaBr 3, T) = 24,0 +/- 2 cal/K.mol Delta H degrees(v, LaI3, T) = 49,5 +/- 2 kcal/mol, Delta S degrees(v, LaI3, T) = 29,0 +/- 2 cal/K.mol.