Ion association in CuSO4 aqueous solutions up to 473 K

MÉNDEZ DE LEO, LUCILA P.; BIANCHI, HUGO L.; FERNÁNDEZ-PRINI, ROBERTO J.

Kyoto, Japan

Conferencia; General Meeting of The International Association for the Properties of Water and Steam; 2004

International Association for the Properties of Water and Steam

The ionic assocn. of copper(II) and sulfate ions in water at high temperature has been studied using a modular spectrophotometer and a titanium high pressure flow cell with sapphire windows.  The UV-spectra of different mixtures of copper(II) and sulfate were determined from room temperature up to 473 K.  A non linear least squares fitting procedure that employed the Pitzer ion interaction model for the activity coefficients and considered other chemical equilibria existing in the solnutios -such as hydrolysis of sulfate and of copper, was used to obtain the equilibrium constants in each condition studied.  Bjerrum´s model was employed to interpret the equil.  Results indicate that copper sulfate ion pairs may be sepd. by mols. of solvent (SSIP) or in contact (CIP).  The former structure predominates at temps. up to 350 K while the latter above 350 K.  The interaction between the ions and between ions and solvent mols. proved to be a main feature in the relative stability of SSIP and PIC.