Study of the Influence of Ionic Strength on the Ionic Product of Water in Saline Media at 25°C Using the Pitzer Equations

1995 ◽  
Vol 99 (5) ◽  
pp. 749-752 ◽  
Author(s):  
Isabel Brandariz ◽  
Sarah Fiol ◽  
Manuel Sastre De Vicente
Keyword(s):  
Ionic Strength ◽  
Pitzer Equations ◽  
Ionic Product

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.

Prediction of Dissociation Constants of Ammonium Ion in 20 Mass % Ethanol + Water Mixed Solvent Solutions Containing Sodium Chloride

1997 ◽  
Vol 52 (11) ◽  
pp. 1372-1375
Author(s):  
Masunobu Maeda ◽  
Chisako Iwata
Keyword(s):  
Sodium Chloride ◽  
Ionic Strength ◽  
Mixed Solvent ◽  
Dissociation Constants ◽  
Glass Electrode ◽  
Ammonium Ion ◽  
Pitzer Equations ◽  
Transpiration Method

Abstract Dissociation constants of amonium ion (Ka= [H +][NH3]/[NH4+], where [ ] denotes the con­centration) in 20 mass % ethanol + water mixtures with different concentrations of sodium chloride were determined by means of a glass electrode. The dissociation constants in pKa units (on molarity and molality bases) increase linearly with increasing ionic strength. Activ­ity coefficients of ammonia in the ethanol + water mixtures were determined by a transpiration method. The observed dissociation constants on the molality scale were compared with those calculated from the Pitzer equations modified on the basis of the principles of corre­sponding states. The observed values agreed with the calculated ones almost within experi­mental uncertainties.

Thermodynamic modeling of metal-ligand interactions in high ionic strength NaCl solutions: the Co2+-oxalate system

2000 ◽  
Vol 88 (9-11) ◽  
Author(s):  
M. Borkowski ◽  
Gregory R. Choppin ◽  
Robert C. Moore
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Stability Constant ◽  
Aqueous Solutions ◽  
High Ionic Strength ◽  
Pitzer Equations ◽  
Ligand Interactions ◽  
Oxalate Ion ◽  
Apparent Stability ◽  
Metal Ligand

First and second apparent stability constants for cobalt(II) with oxalate ion have been determined using solvent extraction. Data were collected in 0.3 m to 5.0 m NaCl aqueous solutions. The logarithms of first stability constant ranged from 3.30 ± 0.03 to 3.57 ± 0.03 and second stability constant ranged from 5.49 ± 0.05 to 6.02 ± 0.06. The data were modeled using the Pitzer equations. For the 1:1 complex, values of the μ

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.

Densities and apparent molar volumes of aqueous NaCl–KBr mixtures at 298.15 K

1985 ◽  
Vol 63 (11) ◽  
pp. 3200-3202 ◽  
Author(s):  
Anil Kumar
Keyword(s):  
Ionic Strength ◽  
High Ionic Strength ◽  
Apparent Molar Volumes ◽  
Excess Volumes ◽  
Pitzer Equations ◽  
Molar Volumes ◽  
Pitzer Formalism ◽  
Volumes Of Mixing

Experimental differences in densities Δd of aqueous NaCl–KBr mixtures at I = 1, 2, 3, and 4 mol kg−1 and at 298.15 K are reported from pure NaCl to pure KBr solutions. Mean apparent molar volumes [Formula: see text] are calculated and excess volumes of mixing [Formula: see text] are correlated by Friedman equation, Δd and [Formula: see text] are analysed in terms of recently developed the Pitzer formalism without and with mixing terms. Pitzer equations can estimate the densities of such mixtures with uncommon cations and anions within ±0.02% at the high ionic strength of 4 mol kg−1.

Pitzer and Thermodynamic Parameters of Triethanolamine and Glycine in Aqueous Saline Solutions

1993 ◽  
Vol 58 (6) ◽  
pp. 1269-1278 ◽  
Author(s):  
Roberto Herrero ◽  
Isabel Brandariz ◽  
Sarah Fiol ◽  
Manuel Sastre de Vicente
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Equilibrium Constant ◽  
Thermodynamic Parameters ◽  
Thermodynamic Quantities ◽  
Pitzer Equations ◽  
Ionic Interaction ◽  
Ionic Strength Dependence ◽  
Strength Dependence ◽  
Saline Solutions

On the basis of the ionic strength dependence of the equilibrium constant (pK*) of thriethanolamine (TEA) and glycine, the ionic interaction parameters of the species involved in the equilibria TEAH+ ↔ TEA + H+ (for TEA), AH2+ ↔ AH + H+ and AH ↔ A- + H+ (for glycine) in aqueous solutions of KCl and KNO3, respectively, were determined using the Pitzer equations. Values of pK* were expressed on both the molarity and the molality scale at various temperatures and values of thermodynamic quantities ∆G0, ∆H0 and ∆S0 ascertained, for TEA.

Solid-Solute Phase Equilibria in Aqueous Solutions IX. Thermodynamic Analysis of Solubility Measurements: La(OH)m(CO3)q•rH2O

1995 ◽  
Vol 50 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Heinz Gamsjäger ◽  
Harald Marhold ◽  
Erich Königsberger ◽  
Yi Jung Tsai ◽  
Hans Kolmer
Keyword(s):  
Ionic Strength ◽  
Gibbs Energy ◽  
Aqueous Solutions ◽  
Phase Equilibria ◽  
Thermodynamic Analysis ◽  
Infinite Dilution ◽  
Log P ◽  
Pitzer Equations ◽  
Solubility Constant ◽  
Aqueous Solubilities

The aqueous solubilities of La(OH)0.8(CO3)1.1.0.1 H2O, basic lanthanum carbonate of ancylite type, have been investigated as a function of ionic strength at 25.0 °C. The stoichiometric solubility constants defined by log* KIps0 = log [La3 +] + 1.1 log pCO2 - 3 log [H+] have the values 11.10, 11.32, 11.42, 11.63, and 11.70 for I = 0.1, 0.25, 1.0, 2.0, and 4.0 mol kg -1(Na)ClO4 respectively. The extrapolation to infinite dilution using the Pitzer equations resulted in a "thermodynamic" solubility constant, log* K°pz0 = 10.48 ± 0.08. This in turn led to the Gibbs energy of ancylite formation: Δf G⊖298 {La(OH)0.8(CO3)1.1 · 0.1 H2O} = - 1.531.5 kJ mol-1.

The ionic strength dependence of chromatin folding

1978 ◽  
Vol 36 (2) ◽  
pp. 220-221
Author(s):  
F. Thoma ◽  
TH. Koller
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ionic Strength ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Carbon Supports ◽  
Ionic Strength Dependence ◽  
Chromatin Folding ◽  
Strength Dependence ◽  
Preparation Techniques

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.

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