Potentiometric Study on the Interactions between Divalent Cations and Sodium Carboxylates in Aqueous Solution

2013 ◽  
pp. 23-33
Author(s):  
Rui Pereira ◽  
Artur Valente ◽  
Hugh Burrows ◽  
Victor Lobo
Keyword(s):  
Aqueous Solution ◽  
Divalent Cations ◽  
Potentiometric Study

Supramolecular assemblies of phenyl-pyridyl-triazolopyridine and β-cyclodextrin as sensor of divalent cations in aqueous solution

2015 ◽  
Vol 121 ◽  
pp. 295-301 ◽  
Author(s):  
Carolina Jullian ◽  
Samuel Fernández-Sandoval ◽  
Cristian Celis-Barros ◽  
Belén Abarca ◽  
Rafael Ballesteros ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Divalent Cations ◽  
Supramolecular Assemblies

Aluminium(III) and Iron(III) 1,2-Diphenolato Complexes: a Potentiometric Study

1985 ◽  
Vol 38 (5) ◽  
pp. 659 ◽  
Author(s):  
JA Kennedy ◽  
HKJ Powell
Keyword(s):  
Aqueous Solution ◽  
Potentiometric Titration ◽  
Protocatechuic Acid ◽  
Acid System ◽  
Experimental Conditions ◽  
Potentiometric Study ◽  
Hydroxo Complexes ◽  
Equilibrium Reactions ◽  
Ternary Metal ◽  
Metal Ligand

The equilibrium reactions between aluminium(III) and the phenols catechol (LH2), protocatechuic acid (LH3) and catechin (LH4), and between iron(III) and protocatechuic acid have been studied by potentiometric titration in aqueous solution, I 0.10M ( KCl ), 25°C. Stability constants are reported for the mononuclear diphenolato complexes AlLHn-2, Al(LHn-2)2and Al(LHn-2)3, and the hydroxo complexes Al(OH)LHn-2 and Al(OH)(LHn-2)2, n = 2 ( catechol ) or 4 ( catechin ). For protocatechuic acid, the carboxylate -coordinated species lLH22+ and the species AlLH + (carboxyl- protonated ) are also postulated. Analogous species were characterized for the iron(III)- protocatechuic acid system. Stoichiometric end-points were obtained only if an excess of ligand was used (L/M > 4). Monomeric and polymeric aluminium- hydroxo species and ternary metal- ligand - hydroxo species were found to be unimportant under the experimental conditions employed.

Ionic association in aqueous solutions of bivalent sulphates

1969 ◽  
Vol 313 (1512) ◽  
pp. 131-147 ◽  
Keyword(s):  
Aqueous Solution ◽  
Osmotic Coefficient ◽  
Dissociation Constants ◽  
Divalent Cations ◽  
Ion Pairs ◽  
Osmotic Coefficients ◽  
Close Approach ◽  
Complete Analysis ◽  
Hydration Water ◽  
Similar Magnitude

Osmotic coefficient data for the sulphates of Mg, Ca, Zn, Ni and Cu in aqueous solution have been analysed to obtain the dissociation constants (d.c.) of ion pairs, triplets and quadruplets, as well as information on their state of hydration. The d.c.’s of the sulphate ion pairs, though of similar magnitude, show distinct individualities, and the trend is similar to that of the d.c.’s calculated for the nitrates of di-valent ions, though the d.c.’s of the latter are about 200 times larger. The d.c.’s of the ion triplets show no correlations, but their absolute values are similar to those calculated from the theory of Fuoss & Kraus (1933, 1935) based on electrostatic considerations. The hydration parameters of the associated sulphates (both pairs and triplets), as characterized in the linear (statistical) terms of the osmotic coefficients, are only slightly smaller than those of the fully dissociated electrolytes, indicating that there is only little loss of hydration water in the process of association, in spite of the heavy hydration of the divalent cations and the relatively close approach of the sulphate ion. The complete analysis of the osmotic coefficient curves makes it possible to calculate the absolute values of the activity coefficients of the divalent sulphates (previously not known to any accuracy).

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