Acid dissociation constants and rates as studied by ultrasonic absorption

1976 ◽  
Vol 54 (20) ◽  
pp. 3152-3162 ◽  
Author(s):  
Larry W. Green ◽  
Peeter Kruus ◽  
M. Jacqueline McGuire
Keyword(s):  
Rate Constant ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Solutions ◽  
Ultrasonic Absorption ◽  
Absorption Data ◽  
Acid Dissociation Constants ◽  
Density Data ◽  
Sulfuric Acid Solutions ◽  
Experimental Density

Experimental ultrasonic absorption data on solutions of H2SO4 and H3PO4 are interpreted in terms of proton transfer equilibria. The acid dissociation constants obtained are compared with those obtained using other methods and are shown to be consistently lower. A model is proposed to explain this in terms of ΔVθ and ΔHθ involved in the steps leading to recombination of the proton with the anion. This model is supported by the values of the reaction distance parameters calculated from the value of the rate constant obtained for the recombination rate. The accuracy of this rate constant is dependent on the accuracy of the ΔVθ value used for the equilibrium. Experimental density data are presented here as an aid in determining ΔVθ. Problems involving activity coefficients in such solutions are discussed in the course of checking the values used for species present in sulfuric acid solutions.

scholarly journals The Kinetics of Chitosan Degradation in Organic Acid Solutions

Marine Drugs ◽  
2021 ◽  
Vol 19 (5) ◽  
pp. 236
Author(s):  
Dominik Sikorski ◽  
Karolina Gzyra-Jagieła ◽  
Zbigniew Draczyński
Keyword(s):  
Organic Acid ◽  
Dissociation Constants ◽  
Degradation Process ◽  
Acid Dissociation ◽  
Acid Solutions ◽  
Spectroscopy Analysis ◽  
Acid Dissociation Constants ◽  
Spinning Process ◽  
Kinetics Of ◽  
Selection Of

This paper presents a comparative study on chitosan degradation in organic acid solutions according to their different dissociation characteristics. More precisely, the aim of the study was to determine the kinetics of the degradation process depending on the different acid dissociation constants (pKa values). The scientists involved in chitosan to date have focused mainly on acetic acid solutions. Solutions of lactic, acetic, malic, and formic acids in concentrations of 3% wt. were used in this research. The progress of degradation was determined based on the intrinsic viscosity measurement, GPC/SEC chromatographic analysis, and their correlation. Changes in the viscosity parameters were performed at a temperature of 20 °C ± 1 °C and a timeframe of up to 168 h (7 days). The chemical structure and DDA of the initial chitosan were analyzed using 1H-NMR spectroscopy analysis. The results of this study can be considered of high importance for the purpose of electrospinning, production of micro- and nano-capsules for drug delivery, and other types of processing. Understanding the influence of the dissociation constant of the solvent on the kinetics of chitosan degradation will allow the selection of an appropriate medium, ensuring an effective and stable spinning process, in which the occurrence of polymer degradation is unfavorable.

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