Abstract: | Gibbs energies of formation have been determined by conductometric titration for hydroxo complexes of cerium, samarium, europium, erbium, ytterbium, and yttrium. All these elements form monohydroxo complexes; yttrium, erbium, and terbium also form dihydroxo complexes. The Gibbs energies of formation of lanthanide hydroxo complexes from ions have virtually equal values of −47.3 ± 0.6 kJ/mol monohydroxo complexes and −44.5 ± 0.5 kJ/mol for dihydroxo complexes, respectively. These values were used to estimate the Gibbs energies of formation of hydroxo complexes for the entire lanthanide series. |