CALORIMETRIC DETERMINATION OF HEATS OF COMPLEXATION OF LANTHANIDE MONOSULFATES LNSO4+

Heats of complexation of the 1:1 sulfate complexes of the trivalent rare earth ions and yttrium have been measured calorimetrically at 25° using the known stability constants. The conditions were corrected to zero ionic strength using an extended form of the Debye-Hückel equation, and the results are compared with values obtained in a 2.0 M perchlorate medium. A linear correlation is observed between log k, the first-order rate constant for complex formation, and log K, the over-all stability constant for the members Ce(III) through Ho(III). This observation is taken as being indicative of a dissociative mechanism.