Estimation of medium effect on enthalpy changes for ionization of water and ammonium ion in aqueous solution

1986 ◽  
Vol 90 (6) ◽  
pp. 1134-1137 ◽  
Author(s):  
Masunobu Maeda
Keyword(s):  
Aqueous Solution ◽  
Medium Effect ◽  
Ammonium Ion ◽  
Enthalpy Changes ◽  
Ionization Of Water

Cyanide Thermodynamics. III. Enthalpies and Entropies of Ionization of Water and Hydrogen Cyanide

1996 ◽  
Vol 49 (6) ◽  
pp. 651 ◽  
Author(s):  
JS Solis ◽  
PM May ◽  
G Hefter
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Stability Constant ◽  
Hydrogen Cyanide ◽  
Infinite Dilution ◽  
Medium Effect ◽  
Titration Calorimetry ◽  
Enthalpy Changes ◽  
The Difference ◽  
Ionization Of Water

The heats (enthalpy changes) associated with the ionization of water and of hydrogen cyanide have been determined by titration calorimetry at 25�C as a function of ionic strength up to 5 M in both NaCl and NaClO4 media. The enthalpy changes for both reactions exhibit a 'medium effect' with ?H being more positive in NaCl than in NaClO4 and with the difference becoming more pronounced with increasing ionic strength. This is attributed to the greater solvation of Cl- cf. CN- in aqueous solution. The present ?H values are similar to previous published results at high ionic strengths, and are in excellent agreement with the well established literature values at infinite dilution. The present ?H values were combined with literature stability constant data to calculate the corresponding entropies for the ionization of H2O and HCN as a function of ionic strength.

Inerte Amminkomplexe als mehrwertige Kationsäuren in wäßriger Lösung / Inert Ammine Complexes as Multivalent Cationic Acids in Aqueous Solution

1980 ◽  
Vol 35 (9) ◽  
pp. 1096-1103 ◽  
Author(s):  
Matthias Kretschmer ◽  
Lutwin Labouvie ◽  
Karl-W. Quirin ◽  
Helmut Wiehn ◽  
Ludwig Heck
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Spectrophotometric Method ◽  
Complex Cation ◽  
Aqua Ligand ◽  
Second Step ◽  
Acidity Constants ◽  
Ammine Complexes ◽  
Temperature Variations ◽  
Enthalpy Changes

Acidity constants of ammine complexes of tetravalent platinum in aqueous solutions have been determined by a spectrophotometric method at very low ionic strengths and extrapolated to zero ionic strength. Temperature variations of pK-values (25 °C and 50 °C) yield thermodynamic parameters for two successive deprotonation steps of hexaammineplatinum(IV), pentaamminechloroplatinum(IV), and tris(ethylenediamine)pla- tinum(IV) complexes and for the deprotonation of pentaammineaquacobalt(III) ion.The enthalpy changes for the first and second steps are similar and range from 50 to 75 kJ/mole while for the aqua ligand of Co(III) 33 kJ/mole are found. The very large dif­ference in the entropy changes (about 70 to 80 J/K mole for the first step and -10 to + 20 J/K mole for the second step) is interpreted by a model of solvation change. The primary hydration sphere of strongly oriented and immobilized water dipoles around the highly charged complex cation is transformed to a hydrogen-bonded solvation sheath when the electric field of the complex is weakened upon release of the first proton.

Monomerie Metaphosphate: Does it Exist in Aqueous Solution?

1987 ◽  
Vol 42 (12) ◽  
pp. 1585-1587 ◽  
Author(s):  
R. G. Keesee ◽  
A. W. Castleman
Keyword(s):  
Aqueous Solution ◽  
Gas Phase ◽  
Water Molecules ◽  
The Third ◽  
Enthalpy Changes ◽  
Successive Addition ◽  
Dihydrogen Orthophosphate

AbstractEnthalpy changes for the successive addition of the first four water molecules onto monomeric metaphosphate anion in the gas phase have been determined to be -12.6, -11.4, -16.3, and - 11.0 kcal/mol, respectively. The results suggest that the first addition is a simple formation of the adduct PO3- · H2O as apposed to formation of the dihydrogen orthophosphate anion (HO)2PO2-, but that the third addition involves a transformation to the orthophosphate anion.

REMOVAL OF AMMONIUM ION FROM AQUEOUS SOLUTION USING MAGNETICALLY MODIFIED ZEOLITE

2008 ◽  
Vol 29 (6) ◽  
pp. 633-639 ◽  
Author(s):  
I. W. Nah ◽  
K.‐Y. Hwang ◽  
Y.‐G. Shul ◽  
C. Jeon
Keyword(s):  
Aqueous Solution ◽  
Ammonium Ion ◽  
Modified Zeolite

The Percent Un-Ionized Ammonia in Aqueous Ammonia Solutions at Different pH Levels and Temperatures

1972 ◽  
Vol 29 (10) ◽  
pp. 1505-1507 ◽  
Author(s):  
R. P. Trussell
Keyword(s):  
Aqueous Solution ◽  
Aqueous Ammonia ◽  
Ammonia Molecule ◽  
Ammonium Ion ◽  
Ready Access ◽  
Freshwater Environments

Previous studies have shown that the un-ionized ammonia molecule and not the ammonium ion is the form of the toxicant harmful to fish. Prior attempts to quantify the amount of un-ionized ammonia in an aqueous solution have been confusing. Data given here provide ready access to the amount of un-ionized ammonia over a range of temperature and pH that is common in temperate freshwater environments.

scholarly journals The Thermodynamics of Copper (II) and Nickel (II)- Diamine Complex Formation in Aqueous Solution

2021 ◽  
Author(s):  
◽  
Harry Kipton James Powell
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Thermodynamic Functions ◽  
Electrode System ◽  
Glass Electrode ◽  
Complex Ions ◽  
Degree Of Hydration ◽  
Enthalpy Changes ◽  
Delta G ◽  
The Stability

<p>This work describes the accurate measurement of the thermodynamic functions Delta G degree and Delta H degree for the step-wise coordination equilibria between each of the ions H+, Ni2+, Cu2+, and, a series of C1-substituted 1,2-diaminoethanes in aqueous solution. The study Involved. (a) The construction of a sensitive constant temperature environment calorimeter for measuring the enthalpy changes in the complex-formation reactions, (b) The rigorous calibration of an electrode system, incorporating a glass electrode, for the direct potentiometric measurement of equilibrium hydrogen ion concentrations in the solutions containing complex ions. The thermodynamic functions Delta G degree and Delta H degree led to accurate Delta S degree values for the step-wise complex-formation reactions. The thesis considers the contribution of the entropy of ligation to the stability of complex ions. The molar entropies of the complex ions have been calculated and their values considered with respect to the coordination number and the possible structure, degree of hydration and steric properties of the ions.</p>

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