Thermodynamic properties of transition metals in aqueous solution:4. The enthalpies of mixing aqueous solutions of CdCl2, CuCl2 and ZnCl2 with MgCl2 at varying ionic strength at 25°C

1993 ◽  
Vol 22 (12) ◽  
pp. 1109-1117 ◽  
Author(s):  
Donald R. Schreiber ◽  
DeVon Andres ◽  
James Huebner
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Transition Metals ◽  
Thermodynamic Properties ◽  
Aqueous Solutions ◽  
Enthalpies Of Mixing

THE DISSOCIATION OF α- AND β-LIPOVITELLIN IN AQUEOUS SOLUTION: PART I. EFFECT OF pH, TEMPERATURE, AND OTHER FACTORS

1962 ◽  
Vol 40 (3) ◽  
pp. 363-372 ◽  
Author(s):  
R. W. Burley ◽  
W. H. Cook
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Thermodynamic Data ◽  
Equilibrium Constants ◽  
Effect Of Ph ◽  
Reversible Dissociation ◽  
Lipoprotein Concentration ◽  
Irreversible Aggregation ◽  
Increasing Temperature

The effect of pH, temperature, ionic strength, and lipoprotein concentration on the reversible dissociation of α- and β-lipovitellin in aqueous solutions above pH 6 has been examined by ultracentrifugal measurements. Under otherwise similar conditions α- and β-lipovitellin are 50% dissociated at pH 10.5 and 7.8, respectively. Both lipovitellins undergo an irreversible aggregation above about pH 11; β-lipovitellin is sometimes converted to a non-dissociable form upon aging. Dissociation of both lipovitellins decreases with increasing ionic strength and increasing temperature. Although the ultracentrifugal method has limitations, provisional equilibrium constants and thermodynamic data were obtained from it that are comparable with those obtained for certain protein systems.

Viscosimetric studies of chitosan nitrate and chitosan chlorhydrate in acid free NaCl aqueous solution

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Cristóbal Lárez Velásquez ◽  
Joel Sánchez Albornoz ◽  
Enrique Millán Barrios
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Aqueous Medium ◽  
Intrinsic Viscosity ◽  
Free Acid ◽  
Film Formation ◽  
Stiffness Parameter ◽  
Low Ionic Strength

AbstractTwo salts of the biopolymer chitosan were prepared in aqueous medium by employing an excess of HCl or HNO3 in order to ensure neutralization of all NH2-chitosan groups. Chitosan salts were extensively dialyzed in dionised water and dried at 40 ºC until film formation. The films were characterized by thermogravimetry, FTIR and conductimetric tritration. QH+Cl− and QH+NO3− salts were viscosimetrically evaluated in free acid aqueous solutions in the presence of NaCl to control ionic strength of the medium. Unexpected high intrinsic viscosity values were obtained at low ionic strength when QH+NO3− salt were evaluated. Smidsrod´s approach was employed to estimate the stiffness parameter of both salts and B = 0.084 and 0.120 for QH+Cl− and QH+NO3−, respectively, were obtained.

THE KINETICS OF THE FORMATION OF THE MONO–FLUORO COMPLEX OF IRON (III) IN AQUEOUS SOLUTION

1960 ◽  
Vol 38 (4) ◽  
pp. 567-575 ◽  
Author(s):  
D. Pouli ◽  
W. MacF. Smith
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Temperature Interval ◽  
Kcal Mole ◽  
Entropy Of Activation ◽  
Fluoro Complex ◽  
Kinetics Of

The kinetics of the reactions involved in the formation of the mono–fluoro complex of iron (III) in aqueous solutions have been examined spectrophotometrically at ionic strength 0.5 and over the temperature interval 0.1 to 12.1 °C. The results are interpretable on the assumption that the following two reactions contribute significantly to the rate Fe+++ + F− = FeF++ and Fe+++ + HF = FeF++ + H+, the former having a heat of activation of 22.8 ± 2.5 kcal mole−1 and an entropy of activation of 35 ± 9 cal deg−1 mole−1, the latter having a heat of activation of 8.7 ± 0.7 kcal mole−1 and an entropy of activation of −24.5 ± 3 cal deg−1 mole−1.

THE DISSOCIATION OF α- AND β-LIPOVITELLIN IN AQUEOUS SOLUTION: PART I. EFFECT OF pH, TEMPERATURE, AND OTHER FACTORS

1962 ◽  
Vol 40 (1) ◽  
pp. 363-372 ◽  
Author(s):  
R. W. Burley ◽  
W. H. Cook
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Thermodynamic Data ◽  
Equilibrium Constants ◽  
Effect Of Ph ◽  
Reversible Dissociation ◽  
Lipoprotein Concentration ◽  
Irreversible Aggregation ◽  
Increasing Temperature

The effect of pH, temperature, ionic strength, and lipoprotein concentration on the reversible dissociation of α- and β-lipovitellin in aqueous solutions above pH 6 has been examined by ultracentrifugal measurements. Under otherwise similar conditions α- and β-lipovitellin are 50% dissociated at pH 10.5 and 7.8, respectively. Both lipovitellins undergo an irreversible aggregation above about pH 11; β-lipovitellin is sometimes converted to a non-dissociable form upon aging. Dissociation of both lipovitellins decreases with increasing ionic strength and increasing temperature. Although the ultracentrifugal method has limitations, provisional equilibrium constants and thermodynamic data were obtained from it that are comparable with those obtained for certain protein systems.

scholarly journals STANDARD FORMATION ENTHALPIES OF HYDROXYETHYLIDENEDIPHOSPHONIC ACID AND PRODUCTS OF ITS DISSOCIATION IN AQUEOUS SOLUTION

2018 ◽  
Vol 61 (4-5) ◽  
pp. 37
Author(s):  
Alexander I. Lytkin ◽  
Viktor V. Chernikov ◽  
Olga N. Krutova ◽  
Ivan A. Skvortsov
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Enthalpies Of Formation ◽  
Formation Enthalpies ◽  
Different Temperatures ◽  
Heat Value ◽  
Standard Enthalpies Of Formation ◽  
Changes Over Time ◽  
Stepwise Dissociation

This study aimed the measuring the standard enthalpies of formation of hydroxyethylidenediphosphonic acid and the products of its dissociation in aqueous solutions at 298.15 K. In the literature there is a large amount of data on the constants of stepwise dissociation of the acid. The works were done at different temperatures and the values of the ionic strength of the solution on the background of the different nature of the supporting electrolytes. In order to compare the values of the constants of stepwise dissociation of the acid, obtained by different authors, we recalculated the values of рK1, рK2, рK3, рК4, рК5 at zero ionic strength by the Davies equation. The most probable values of thermodynamic constants of dissociation of hydroxyethylidenediphosphonic acid were the following: рК10 = 1.7±0.03; рК20 = 2.47±0.05; рК30 = 7.78±0.05; рК40 = 10.29±0.05 and pK50 = 11.13±0.05. Calorimetric measurements were performed on an ampoule calorimeter equipped with an isothermal shell and a KMT-14 thermistor temperature sensor, and the automatic recording the temperature changes over time. The operation of installation was verified with the integral enthalpies of dissolution in water of crystalline potassium chloride and was considered suitable for measurements, if certain it ∆solН298.15 (KCl ∞ H2O)=17.234± 0.018 kJ/mol, corresponding to the standard SRM 1655NBS. The heat value of the calorimeter water was 87±12 Дж/mol virtually coincided with the thermal value of the calorimeter for potassium hydroxide. The volume of the calorimetric liquid was 43.12 ml. The hydroxyethylidenediphosphonic acid samples were weighed on a VLR-200 balance with 2∙10-4 g accuracy. The confidence range of the average ΔН value was determined at 0.95 probability. The equilibrium compositions of solutions were calculated using RRSU software. The standard enthalpies of formation of hydroxyethylidenediphosphonic acid and the products of its dissociation in aqueous solutions were calculated.Forcitation:Lytkin A.I., Chernikov V.V., Krutova O.N., Skvortsov I.A. Standard formation enthalpies of hydroxyethylidenediphosphonic acid and products of its dissociation in aqueous solution. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 37-42

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