Solid-solute phase equilibria in aqueous solutions, VIII: The standard gibbs energy of La2(CO3)3.8H2O

Nguyen, A.M., Königsberger, E., Marhold, H. and Gamsjäger, H. (1993) Solid-solute phase equilibria in aqueous solutions, VIII: The standard gibbs energy of La2(CO3)3.8H2O. Monatshefte fur Chemie//Chemical Monthly, 124 (10). pp. 1011-1018.

Abstract

The solubilities of lanthanum carbonate La2(CO3)3·8H2O in solutions S0([H+]=H mol kg-1, [Na+]=(I-H) mol kg-1, [ClO4-]=I mol kg-1) at various fixed partial pressures of CO2 have been investigated at 25.0 °C. The hydrogen ion molality and the total molality of La(III) ion in equilibrium with the solid phase were determined by e.m.f. and analytical methods, respectively. The stoichiometric solubility constants {Mathematical expression} according to the overall reaction {Mathematical expression} have the values 10.23, 10.37, 10.58, 10.77 and 11.06 for I=0.1, 0.25, 1.0, 2.0 and 4.0 mol kg-1 (Na)ClO4, respectively. The extrapolation to infinite dilution using the Pitzer equations resulted in a "thermodynamic" solubility constant: {Mathematical expression}. This in turn led to the Gibbs energy of lanthanite, La2(CO3)3·8H2O, formation: {Mathematical expression}.

Publication Type:	Journal Article
Publisher:	Springer Verlag
Copyright:	© 1993 Springer-Verlag
URI:	http://researchrepository.murdoch.edu.au/id/eprint/7295

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