Effets des cations alcalins et pseudo-alcalins sur quelques équilibres et en particulier sur l'équilibre d'extraction de l'acide thiocyanique par la méthylisobutylcétone

1976 ◽  
Vol 54 (1) ◽  
pp. 19-23
Author(s):  
Louise Schriver
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constant ◽  
Aqueous Phase ◽  
Association Constant ◽  
Ion Pairs ◽  
Constant Ionic Strength ◽  
Thiocyanic Acid ◽  
Alkaline Cations ◽  
Methylisobutyl Ketone

The equilibrium constant for the extraction of thiocyanic acid by methylisobutyl ketone at constant ionic strength, depends on the nature of alkaline cations present in the aqueous phase. The phenomenon could be explained by the existence of ion pairs for which the association constant Kp is derivable. However the extraction of chlorpromazinium thiocyanate by the same solvent and the formation of the monothiocyanate complex of zirconium in aqueous phase are both independent of the nature of the electrolyte. The observed variations for the extraction of thiocyanic acid which exist also for the extraction of hydrochloric and perchloric acids by methylisobutyl ketone, result from the variation of species activities with a change in the identity of the cations.

Extraction of iron(III) from the citric medium by the toluene solution of trilaurylamine

1980 ◽  
Vol 45 (11) ◽  
pp. 3116-3129 ◽  
Author(s):  
Petr Vaňura ◽  
Libor Kuča
Keyword(s):  
Citric Acid ◽  
Ionic Strength ◽  
Aqueous Phase ◽  
Organic Phase ◽  
Toluene Solution ◽  
Constant Ionic Strength ◽  
Extraction Constants ◽  
Equilibrium Concentrations

The composition of Fe(III) complexes extracted from the aqueous phase of constant ionic strength (1M-(H3,Na3,Fe)A, where H3A denotes citric acid) by the toluene solution of trilaurylamine (TLA) has been determined and the respective extraction constants have been calculated. In the concentration range cFe < 10-2 mol l-1 FeA(TLA)2 and FeA(TLA)4(H3A)2-4 are the predominant complexes in the organic phase. The abundance of the (FeA)3(TLA)6(H3A)2 complex in the organic phase increases at higher equilibrium concentrations of Fe(III) in the aqueous phase and at higher concentrations of TLA.

Kinetics and mechanisms of oxidations by metal ions. Part VIII. Oxidation of n-propanol by aquomanganese(III) ions

1987 ◽  
Vol 65 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Mahendra Mehta ◽  
Ratan R. Nagori ◽  
Raj N. Mehrotra
Keyword(s):  
Ionic Strength ◽  
Metal Ions ◽  
Equilibrium Constant ◽  
Thermodynamic Parameters ◽  
The Other ◽  
Constant Ionic Strength ◽  
Rate Law

The oxidation of n-propanol by aquomanganese(III) ions in perchlorate medium of constant ionic strength (4 mol dm−3, NaClO4) is described by the rate law [i] which is based on the consideration of the reactions [ii]–[ix].[Formula: see text]A further analysis of the rate law in terms of the results indicated that MnOH2+ (aq) is the major oxidant. The values of the equilibrium constant (β1) and rate determining constant (k1) are reported together with the associated thermodynamic parameters. The values of the other constants, k, Ka, and β, could not be determined though an assumption was made that β ≈ β1.

Equilibrium constants of pyridoxal 5'-phosphate Schiff bases - A polarographic study

1983 ◽  
Vol 48 (7) ◽  
pp. 1950-1955 ◽  
Author(s):  
Juan Llor ◽  
Javier Bonal ◽  
Manuel Cortijo
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Equilibrium Constant ◽  
Schiff Bases ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Constant Ionic Strength ◽  
Polarographic Study ◽  
Ionic Forms

The equilibrium constant for the formation of the Schiff base between pyridoxal 5'-phosphate and n-hexylamine has been evaluated from polarographic measurements. The pH dependence of the equilibrium constant has been investigated at constant ionic strength. The values thus obtained for the equilibrium constant compare well with those computed from the pK of the several ionic forms of pyridoxal 5'-phosphate, its Schiff base and the amine present in the solution.

Adsorption of chlorate and bromate ions on mercury electrodes from constant ionic strength solutions

1988 ◽  
Vol 85 ◽  
pp. 523-527
Author(s):  
M.M. Zuleika ◽  
Palhares SILVA ◽  
Ernesto Rafael GONZALEZ ◽  
Luis Alberto AVACA ◽  
Artur de Jesus MOTHEO
Keyword(s):  
Ionic Strength ◽  
Constant Ionic Strength ◽  
Mercury Electrodes

Extraction of hafnium(IV) with organophosphorus reagents from solutions of mineral acids mixtures

1979 ◽  
Vol 44 (12) ◽  
pp. 3656-3664
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola ◽  
Rostislav Kolouch
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Organic Phase ◽  
Perchloric Acid ◽  
Synergic Effect ◽  
Salting Out ◽  
Initial Concentration ◽  
Mixed Complexes ◽  
Synergic Extraction ◽  
Mineral Acids

Extraction of hafnium(IV) was studied from solutions of mixtures of perchloric and nitric acids and of perchloric and hydrochloric acids for constant ionic strength, I = 2, 4, 6, or 8, and for cHf 4 . 10-4 mol l-1. The organic phase was constituted by solutions of some acidic or neutral organophosphorus reagents or of 2-thenoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, or N-benzoyl-N-phenylhydroxylamine in benzene, chloroform, or n-octane. A pronounced synergic extraction of hafnium proceeds only on applying organophosphorus reagents from an aqueous phase whose acidity is not lower than 3M-(HClO4 + HNO3) or 5M-(HClO4 + HCl). The synergic effect was not affected markedly by a variation of the initial concentration of hafnium in the range 1 . 10-8 -4 .10-4 mol l-1, it lowered with increasing initial concentration of the organophosphorus reagent and decreasing concentration of the H+ ions. It is suggested that the hafnium passes into the organic phase in the form of mixed complexes, the salting-out effect of perchloric acid playing an appreciable part.

Extraction of hafnium by means of some substituted 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-ones

1981 ◽  
Vol 46 (8) ◽  
pp. 1901-1905 ◽  
Author(s):  
Oldřich Navrátil ◽  
Jiří Smola
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Dissociation Constants ◽  
Parent Substance ◽  
Benzoyl Group ◽  
Extraction Constants ◽  
Extraction Parameters ◽  
Substituted 1

Distribution between aqueous phase and benzene or chloroform was studied for 1-phenyl-3-methyl-4-benzoylpyrazol-5-ones with 2-chloro, 4-methoxy, 3-nitro, and 4-nitro substitution in the benzoyl group (ionic strength of the aqueous phase 0.1) and for hafnium in their presence (ionic strength 2.0). The distribution and dissociation constants of the reagents and the extraction constants of their hafnium complexes were determined. Hafnium was found to be extracted as the HfA4 species. The extraction parameters of the derivatives in question do not differ substantially from those of the parent substance.

Kinetics and Mechanism of Hexachloroiridate(IV) Oxidation of Arsenic(III) in Acidic Perchlorate Solutions

1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan
Keyword(s):  
Ionic Strength ◽  
Fractional Order ◽  
Activation Parameters ◽  
Order Reaction ◽  
First Order Reaction ◽  
Intermediate Complex ◽  
Constant Ionic Strength ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Kinetics Of

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.

scholarly journals Influence of intracrystalline ionic strength in MFI zeolites on aqueous phase dehydration of methylcyclohexanols

2021 ◽  
Author(s):  
Lara Milaković ◽  
Peter Hintermeier ◽  
Yue Liu ◽  
Eszter Barath ◽  
Johannes Lercher
Keyword(s):  
Ionic Strength ◽  
Aqueous Phase ◽  
Mfi Zeolites

EUROPIUM OXALATE ION ASSOCIATION IN WATER

1966 ◽  
Vol 44 (24) ◽  
pp. 3057-3062 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Stability Constant ◽  
Stability Constants ◽  
Aqueous Phase ◽  
Sodium Acetate ◽  
Ion Association ◽  
Sodium Oxalate ◽  
Aqueous Sodium ◽  
Oxalate Ion

The partitioning of radiotracer 152/151Eu between aqueous sodium oxalate (Na2L) solutions and toluene solutions of thenoyltrifluoroacetone (HTTA) has been studied as a function of the oxalate concentration. The pH of the aqueous phase was controlled by means of sodium acetate – acetic acid mixtures and the ionic strength (I) by NaCl or NaClO4.At low ionic strengths (~0.05) and [L] ~10−4 M EuL+ formed, but at I = 0.95 and [L] ~10−3 M EuL2− also formed. Stability constants for the 1:1 and 1:2 (metal:ligand) complexes are reported.The magnitudes of the stepwise stability constant ratios are discussed.

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