Ionization of Water in Concentrated Potassium Halide Media

2000 ◽  
Vol 53 (5) ◽  
pp. 369 ◽  
Author(s):  
Faradj K. Samani ◽  
Stephen G. Capewell ◽  
Pal M. Sipos ◽  
Peter M. May ◽  
Glenn Hefter
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
High Precision ◽  
Excellent Agreement ◽  
Ion Pairs ◽  
Formation Constants ◽  
Glass Electrode ◽  
Ionic Product ◽  
Ionization Of Water ◽  
Potassium Halide

The ionic product of water, pKw = –log[H+][OH–], has been determined as a function of ionic strength (I ) in concentrated aqueous solutions of KCl, KBr and KI at 25˚C by high-precision glass electrode potentiometric titrations. The pKw values obtained are in excellent agreement with, but generally more precise than, literature data. At I > 1 M the pKw values increase smoothly and show systematic differences in the order KCl < KBr < KI, consistent with the decreasing H+-acceptor ability of the medium anions. Analogous behaviour is observed in MCl solutions, with pKw values varying in the order NaCl < KCl < CsCl. Formation constants of MOH0 ion pairs derived from these data are consistent with literature values.

ION PAIR EFFECTS IN THE REACTION BETWEEN POTASSIUM FERROCYANIDE AND POTASSIUM PERSULFATE

1966 ◽  
Vol 44 (4) ◽  
pp. 437-445 ◽  
Author(s):  
R. W. Chlebek ◽  
M. W. Lister
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Ion Pairs ◽  
Ion Pair ◽  
Glass Electrode ◽  
Potassium Ferrocyanide ◽  
Potassium Persulfate ◽  
Ion Concentration ◽  
True Rate

The rate of the reaction between potassium ferrocyanide and potassium persulfate has been measured over a range of conditions. The rate is dependent on the potassium ion concentration, and it is shown that this is explained if it is assumed that KFe(CN)63− and KS2O8− are the reacting species. The equilibrium constants governing the formation of these ion pairs were measured with a cation-sensitive glass electrode. Similar constants for the products KFeCCN6)2− and KSO4−, and also for KNO3, were measured. From these equilibrium constants, the true rate constants of the reaction can be obtained, and it is shown that these vary with ionic strength in the manner predicted by Brönsted's equation.

scholarly journals Potentiometric and Blood Plasma Simulation Studies of Nickel(II) Complexes of Poly(amino)amido Pentadentate Ligands: Computer Aided Metal-Based Drug Design

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Sebusi Odisitse ◽  
Graham E. Jackson
Keyword(s):  
Ionic Strength ◽  
Blood Plasma ◽  
Formation Constants ◽  
Glass Electrode ◽  
Plasma Simulation ◽  
Simulation Studies ◽  
Plasma Model ◽  
Computer Aided ◽  
Pentadentate Ligands

The thermodynamic equilibria of nickel(II) with N,N′-di(aminoethylene)-2,6-pyridinedicarbonylamine (L1), Bis-(N,N-dimethylethyl)-2,6-pyridinedicarboxamide (L2), and N,N′-bis[2(2-pyridyl)-methyl]pyridine-2,6-dicarboxamide (L3) have been studied at 25°C and an ionic strength of 0.15 mol dm−3by glass electrode potentiometry. The protonation and formation constants added to blood plasma model predict that Cu(II) competes effectively against Ni(II), Zn(II), and Ca(II) for these ligandsin vivo.

scholarly journals Applied aspects of acid-base interactions and modelling equilibrium concentrations in two-component acid mixtures

2020 ◽  
Vol 10 (3) ◽  
pp. 393-400
Author(s):  
B. B. Tanganov
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Charged Particles ◽  
Material Balance ◽  
Mass Action ◽  
Develop Model ◽  
Acid Base ◽  
Ionic Product ◽  
Weak Electrolytes ◽  
Equilibrium Concentrations

Fundamental and applied research into aqueous and non-aqueous solutions of strong and weak electrolytes remains to be highly relevant, which fact is confirmed by a large number of Russian and foreign publications. In almost all such publications, acid-base interactions are considered exclusively with regard to changes in hydrogen ion concentrations. However, the ionic strength of solutions is determined by all ions present in the system, the concentration of which varies during interactions. This is particularly true for potentiometric titration of strong and weak electrolytes not only in aqueous, but also in more complex non-aqueous solutions, which differ significantly in their basic properties (dielectric constant, ionic product, dipole moment, viscosity, etc.). In the study of equilibria, it is more feasible to develop model representations that would greatly simplify and facilitate the computation and evaluation of certain properties of the system under consideration. In this work, acid-base interactions are presented in the form of equations based on mass action laws and those describing equilibrium processes, solvent ionic product, electroneutrality and material balance in electrolyte systems. The proposed equations consider the effect of the concentrations of all charged particles in the system (not only of hydrogen ions – pH) on the ionic strength of the solution, activity coefficients and, as a consequence, the thermodynamic dissociation constant. In addition, these equations allow the dependence between the equilibrium concentrations of all charged particles and the solution acidity determined by the potentiometric method to be expressed in convenient and objective logarithmic coordinates, thus facilitating estimation of the concentration of all particles at any moment of titration.

Chemical Speciation in the Copper (I)-Ammonia-Chloride System

1995 ◽  
Vol 48 (7) ◽  
pp. 1283 ◽  
Author(s):  
JS Solis ◽  
G Hefter ◽  
PM May
Keyword(s):  
Ionic Strength ◽  
General Equilibrium ◽  
Chemical Speciation ◽  
Ionization Constant ◽  
Protonation Constant ◽  
Formation Constants ◽  
Glass Electrode ◽  
Ternary Complexes ◽  
Chloride System ◽  
Binary And Ternary Complexes

Chemical speciation in the system CuI/NH3/Cl- which may be represented by the general equilibrium pCuI(aq)+qNH3(aq)+rCl-(aq)↔ Cup(NH3)qClr(p-r)+(aq) has been studied by glass electrode potentiometry at 25.0°C and an ionic strength of 1.00 M (NaClO4). A number of binary and ternary complexes were detected with formation constants, βpqr: logβ120 = 11.381�0.077, logβ111 = 8.920�0.045, logβ112 = 8.82�0.18 and logβ121 = 11.33�0.24. The ionization constant of water (pKw) and the protonation constant of ammonia (pKa) obtained by the same procedures were 13.7462�0.0012 and 9.4613�0.0010 at I = 1 (NaClO4), and 13.7165�0.0010 and 9.4521�0.0007 at I = 1 (NaCl) respectively.

Formation constants for selected organo—metal (Al3+, Fe3+)—phosphate complexes

1985 ◽  
Vol 63 (12) ◽  
pp. 3357-3366 ◽  
Author(s):  
Paul A. Arp ◽  
W. Lense Meyer
Keyword(s):  
Organic Acids ◽  
Aqueous Solutions ◽  
Reference Electrode ◽  
Formation Constants ◽  
Glass Electrode ◽  
Metal Phosphate ◽  
Electrode Pair ◽  
Phosphate Ions

The possible formation of organo–metal–phosphate complexes (O–M–P) in aqueous solutions is examined by potentiometric titration analysis. The complex-forming solutions contain Al3+-ions or Fe3+-ions, organic acids (salicylic, phthalic, oxalic, and citric acids) and phosphate ions. The titrations are done within the precipitation-free pH-region from 2 to 4.5 (approximately) at 25 °C under nitrogen at an ionic strength of 0.2 M KCl. The calibration of the electrode pair (glass-electrode, calomel-reference electrode) and the determination of the formation constants are facilitated by analyzing the pertinent curves with the ACBA-(Arena etal.) and MINIQUAD-(Gans etal.) computer programs. The results suggest (i) that O–M–P complexes are readily formed, and that the power of selected organic acids to form ternary mixed-ligand complexes with Al3+-ions and phosphate ions decreases in the order salycilate > citrate > oxalate > phthalate. Also, Fe3+-ions are found to be more strongly bound by salicylate and phosphate ions than Al3+-ions. The effect of O–M–P formation on the chemical speciation of Al in buffered aqueous solutions containing mineral nutrients for the growth of biological organisms is demonstrated for a special case study.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

1994 ◽  
Vol 59 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
Ladislav Svoboda ◽  
Petr Vořechovský
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Sodium Perchlorate ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Point Of View ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Acidic Media ◽  
Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

Ionic-strength dependence of formation constants—XII A model for the effect of background on the protonation constants of amines and amino-acids

Talanta ◽  
1989 ◽  
Vol 36 (9) ◽  
pp. 903-907 ◽  
Author(s):  
A CASALE ◽  
C DESTEFANO ◽  
S SAMMARTANO ◽  
P DANIELE
Keyword(s):  
Amino Acids ◽  
Ionic Strength ◽  
Formation Constants ◽  
Protonation Constants ◽  
Ionic Strength Dependence ◽  
Strength Dependence

Effect of ionic strength on the aggregation kinetics of the amidated amyloid beta peptide Aβ (1-40) in aqueous solutions

2017 ◽  
Vol 228 ◽  
pp. 98-107 ◽  
Author(s):  
Adriana Campos-Ramírez ◽  
Maripaz Márquez ◽  
Liliana Quintanar ◽  
Luis F. Rojas-Ochoa
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Amyloid Beta ◽  
Amyloid Beta Peptide ◽  
Aggregation Kinetics ◽  
Beta Peptide ◽  
Kinetics Of
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