Thermodynamics of ionization of aqueous alkanolamines

1987 ◽  
Vol 65 (8) ◽  
pp. 1726-1728 ◽  
Author(s):  
Jin-Ho Kim ◽  
Celina Dobrogowska ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Glass Electrode ◽  
Electrochemical Measurements ◽  
Calorimetric Measurements ◽  
Protonated Species ◽  
Thermodynamics Of Ionization

We have made electrochemical measurements with a glass electrode that have yielded pK values at T = 298.15 K for monothanolamine (MEA), triethanolamine (TEA), diisopropanolamine (DIPA), and methyldiethanolamine (MDEA) relative to the already well-known pK for diethanolamine (DEA), with all pK values referring to equilibria of the type AmH+(aq) = Am(aq) + H+(aq) in which Am(aq) represents an alkanolamine in aqueous solution and AmH+(aq) represents the corresponding protonated alkanolamine. We have also made calorimetric measurements leading to ΔH0 values for dissociation of the protonated species of all five of these alkanolamines in aqueous solution at T = 298.15 K. These pK and ΔH0 values have led to ΔG0 and ΔS0 values for the corresponding dissociation reactions of all five AmH+(aq) species.

Thermodynamics of Ionization of Nitroethane in Water–Ethanol Solvent Mixtures

1974 ◽  
Vol 52 (10) ◽  
pp. 1910-1913 ◽  
Author(s):  
Takeki Matsui ◽  
Loren G. Hepler ◽  
Earl M. Woolley
Keyword(s):  
Mixed Solvent ◽  
Aqueous Ethanol ◽  
Equilibrium Constants ◽  
Glass Electrode ◽  
Solvent Mixtures ◽  
Calorimetric Measurements ◽  
Solvent Systems ◽  
Ionization Of Water ◽  
Thermodynamics Of Ionization ◽  
Acid Ionization

We have made glass electrode measurements that lead to values for the equilibrium constant for acid ionization of nitroethane in water and in aqueous ethanol mixed solvent systems. Calorimetric measurements have led to ΔH0 values for the acid ionization of nitroethane in water and in aqueous ethanol. These results have been combined to yield TΔS0 values for the ionization reactions in water and in aqueous ethanol. Our results have also been combined with previously reported equilibrium constants for ionization of water in aqueous ethanol to obtain thermodynamic data for the neutralization of nitroethane in the various solvent systems.

Thermodynamics of Ionization of Fluoroalcohols in Aqueous Solution: Hexafluoropropan-2-ol and Hexafluoropropan-2,2-diol

1971 ◽  
Vol 49 (18) ◽  
pp. 3054-3056 ◽  
Author(s):  
Earl M. Woolley ◽  
Loren G. Hepler ◽  
Rodney S. Roche
Keyword(s):  
Aqueous Solution ◽  
Solvent Interactions ◽  
Calorimetric Measurements ◽  
The Difference ◽  
Thermodynamics Of Ionization

Calorimetric measurements have led to ΔH0 = 6.37 kcal mol−1 for ionization of aqueous hexafluoro-propan-2-ol (HFIP) and to ΔH0 = 6.00 kcal mol−1 for ionization of aqueous hexafluoropropan-2,2-diol (HFPD). We have combined these values with our ΔG0 values from pK = 9.42 for HFIP and pK = 6.65 for HFPD to obtain ΔS0 = −21.7 cal deg−1 mol−1 for ionization of aqueous HFIP and ΔS0 = −10.3 cal deg−1 mol−1 for ionization of aqueous HFPD. These results (all for 298 °K) show that most of the difference in pK values is due to the large difference in entropy of ionization. The ΔS0 values can be explained largely in terms of solute-solvent interactions.

Acid Ionizations of Nitroalkanes in Aqueous Solution

1973 ◽  
Vol 51 (12) ◽  
pp. 1941-1944 ◽  
Author(s):  
Takeki Matsui ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acids ◽  
Equilibrium Constants ◽  
Free Energies ◽  
Methyl Substitution ◽  
Calorimetric Measurements ◽  
Acid Ionizations

Calorimetric measurements have led to ΔH0 values for ionization of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane in aqueous solution at 298°K. Combinations of these enthalpies with free energies from equilibrium constants for ionization have led to ΔS0 values for the ionization reactions. It is noted that the trend toward decreasing pK with methyl substitution in nitroalkanes is unusual compared to phenols and carboxylic acids. Similarly, correlations of ΔS0 with ΔG0 and ΔH0 are different for nitroalkanes than for other acids.

Thermodynamics of ionization processes in aqueous solution. Part 3.—Methyl-substituted phenol

1959 ◽  
Vol 55 (0) ◽  
pp. 1734-1737 ◽  
Author(s):  
H. M. Papée ◽  
W. J. Canady ◽  
T. W. Zawidzki ◽  
K. J. Laidler
Keyword(s):  
Aqueous Solution ◽  
Ionization Processes ◽  
Thermodynamics Of Ionization

Calorimetric investigations of Al3+(aq), Al(OH)4−(aq), and aluminium–citrate complexes at 298.15 K

1997 ◽  
Vol 75 (8) ◽  
pp. 1110-1113 ◽  
Author(s):  
Ching-hsien Wu ◽  
Celina Dobrogowska ◽  
Xin Zhang ◽  
Loren G. Hepler
Keyword(s):  
Aqueous Solution ◽  
Aluminum Hydroxide ◽  
Equilibrium Constants ◽  
A Value ◽  
Calorimetric Measurements ◽  
Aluminum Complexes ◽  
Aluminium Citrate ◽  
Calorimetric Investigations ◽  
Citrate Ions

We have combined results of earlier measurements leading to equilibrium constants for formation and reaction of aluminum–citrate complexes in aqueous solution at 298.15 K with results of our calorimetric measurements at this same temperature to obtain ΔH values for reactions of Al3+(aq) with citrate ions. Results of some of these calorimetric measurements also lead to a value of ΔH for the reaction Al3+(aq) + 4 OH`(aq) = Al(OH)4−(aq). Keywords: aluminum hydroxide, Al(OH)4−(aq), thermodynamics; aluminium–citrate complexes, thermodynamics; citrate–aluminum complexes, thermodynamics; aluminum (3+, aq), thermodynamics.

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>

scholarly journals Characterization of pesticide-β-cyclodextrin inclusion complexes in aqueous solution

2005 ◽  
Vol 3 (2) ◽  
pp. 151-155
Author(s):  
Goran Petrovic ◽  
Blaga Stojceva-Radovanovic ◽  
O. Jovanovic
Keyword(s):  
Aqueous Solution ◽  
Inclusion Complexes ◽  
Ultraviolet Spectrophotometry ◽  
Maximum Solubility ◽  
Complex Stability Constant ◽  
Cyclodextrin Inclusion Complexes ◽  
Cyclodextrin Inclusion ◽  
Calorimetric Measurements ◽  
Poorly Soluble

The solubility of four different pesticides, "dimethoate", "simazine" "linuron" and "thiram", poorly soluble or non-soluble in water, were measured in water and in aqueous solution of ?-cyclodextrin by ultraviolet spectrophotometry. Standard water solutions of pesticides were prepared in the range of concentrations up to the maximum solubility of each pesticide in water. Concentrations of the pesticides were determined as absorbance on the absorption maximum. The obtained results show that the aqueous solution of ?-cyclodextrin was a powerful solubilizer of investigated pesticides due to the formation of inclusion complexes. Effective solubility of some of the pesticides in aqueous ?-cyclodextrin solution was up to three orders of magnitude higher than those in water. Thermodynamic parameters and complex stability constant of the obtained inclusion complexes were determined by the calorimetric measurements.

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