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).

Solution Properties of Tetraalkylammonium Halide and Alkali-Metal Halide Ion Pairs. The Relationship Between Dissociation Constants and Solubility Products

1987 ◽  
Vol 40 (7) ◽  
pp. 1201 ◽  
Author(s):  
W Mizerski ◽  
MK Kalinowski
Keyword(s):  
Alkali Metal ◽  
Solubility Product ◽  
Dissociation Constants ◽  
Ion Pairs ◽  
Empirical Relation ◽  
Alkali Metal Halide ◽  
Alkali Metal Cations ◽  
Solubility Products ◽  
The Relationship ◽  
Dissociation Constant Kd

An empirical relation describing the effect of solvent on the dissociation constant ( Kd ) of ion pairs is described. An equation of the form pKd = apKso + bD-1 + c ( Kso and D stand for the solubility product of a given salt and for the electric permittivity of a solvent, respectively) has been tested with 13 sets of experimental data for salts containing tetraalkylammonium and alkali-metal cations. A successful correlation was obtained in 100% of the cases considered.

Inline Raman Spectroscopy and Indirect Hard Modeling for Concentration Monitoring of Dissociated Acid Species

2020 ◽  
pp. 000370282097327
Author(s):  
Alexander Echtermeyer ◽  
Caroline Marks ◽  
Alexander Mitsos ◽  
Jörn Viell
Keyword(s):  
Aqueous Solution ◽  
Raman Spectroscopy ◽  
Process Analytical Technology ◽  
Dissociation Constants ◽  
A Priori ◽  
Calibration Procedure ◽  
Acid Dissociation ◽  
Multivariate Curve Resolution ◽  
Least Squares Regression ◽  
Fitting Ideal

We propose an approach for monitoring the concentration of dissociated carboxylic acid species in dilute aqueous solution. The dissociated acid species are quantified employing inline Raman spectroscopy in combination with indirect hard modeling (IHM) and multivariate curve resolution (MCR). We introduce two different titration-based hard model (HM) calibration procedures for a single mono- or polyprotic acid in water with well-known (method A) or unknown (method B) acid dissociation constants p Ka. In both methods, spectra of only one acid species in water are prepared for each acid species. These spectra are used for the construction of HMs. For method A, the HMs are calibrated with calculated ideal dissociation equilibria. For method B, we estimate p Ka values by fitting ideal acid dissociation equilibria to acid peak areas that are obtained from a spectral HM. The HM in turn is constructed on the basis of MCR data. Thus, method B on the basis of IHM is independent of a priori known p K a values, but instead provides them as part of the calibration procedure. As a detailed example, we analyze itaconic acid in aqueous solution. For all acid species and water, we obtain low HM errors of < 2.87 × 10−4mol mol−1 in the cases of both methods A and B. With only four calibration samples, IHM yields more accurate results than partial least squares regression. Furthermore, we apply our approach to formic, acetic, and citric acid in water, thereby verifying its generalizability as a process analytical technology for quantitative monitoring of processes containing carboxylic acids.

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

Theory of amphoteric electrolytes. Part II.

1905 ◽  
Vol 74 (497-506) ◽  
pp. 271-280 ◽  
Author(s):  
James Walker
Keyword(s):  
Aqueous Solution ◽  
Dissociation Constants

In a previous paper it was shown that if HXOH is an amphoteric electrolyte, it is possible to express the concentration of the various ions present in its aqueous solution in terms of the concentration of the unionised substance, the dissociation constants of the substance acting as acid and as base respectively, and the ionisation constant of water.

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