Original scientific paper

Precipitation and Hydrolysis of Metallic Ions. III. Studies on the Solubility of Yttrium and Some Rare Earth Hydroxides

Z. Orhanović ; Department of Physical Chemistry, Institute »Ruder BoskoviC«, Zagreb, Croatia, Yugoslavia
B. Pokrić ; Department of Physical Chemistry, Institute »Ruder BoskoviC«, Zagreb, Croatia, Yugoslavia
H. Furedi ; Department of Physical Chemistry, Institute »Ruder BoskoviC«, Zagreb, Croatia, Yugoslavia
M. Branica ; Department of Physical Chemistry, Institute »Ruder BoskoviC«, Zagreb, Croatia, Yugoslavia

Abstract

The solubility limits of lanthanum, praseodymium, neodymium,
samarium, gadolinium, dysprosium , erbium, ytterbium, lutetium, and
yttrium hydroxides hav e been determined by tyndallometric and
pH measurements. The solubility products (log Kso) of these rare
earth hydroxides were determined from the solubility limits by a
simple graphical method. The predominant soluble species are free
or hydrated Ln3+ ions in equilibrium with the formed solid phase.
Since no other step of hydrolysis is evident from the solubility limits,
the reaction for the formation of Ln(OH)3 precipitate may be
written as:
Ln+a + 3 Off -Z Ln(OH)a (s)
The graphically obtained precipitation pH values (C0 ) and the
values calculated for the solubility product (log Ks0 ) indicate that
the basicities of the rare earth elements decrease in the following
order:
La, Pr, Nd, Sm, Er, Gd, Yb, Lu, and Y
The solubility products of th e se rare earth hydroxides have
values ranging from 10-"5 ·1 to 10 ·1 9-9.

Keywords

Hrčak ID:

208145

URI

https://hrcak.srce.hr/208145

Publication date:

28.12.1966.

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