H. Oppermann et al., CALORIMETRY OF LANTHANUM TRIHALIDES AND OF AMMONIUM LANTHANUM HALIDES, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 52(9), 1997, pp. 1062-1066
By determination of the enthalpies of solution of lanthanum oxide and
of lanthanum trihalides in 4n HX we derived the enthalpies of formatio
n of the trihalides at 298 K using tabulated data. On the basis of the
se data and measured enthalpies of solution in 4n HX of diammonium lan
thanum pentahalides, the enthalpies of formation of (NH4)(2)LaX5 were
obtained. Delta H-B degrees(LaCl3,f,298) = -2.58,5 +/- 0,8 kcal/mol; D
elta H-B degrees((NH4)(2)LaCl5,f,298) = 411,5 +/- 1,4 kcal/mol; Delta
H-B degrees(LaBr3,f,298) = -218,7 +/- 1,7 kcal/mol; Delta H-B degrees(
(NH4)(2)LaBr5,f,298) = 352,8 +/- 2,5 kcal/mol; Delta H-B degrees(LaI3,
f,298) = -166,9 +/- 2,0 kcal/mol; Delta H-B degrees((NH4)(2)LaI5,f,298
) = -264,7 +/- 3,0 kcal/mol.