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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 10, Number 3
JKCSEZ 10(3)
June 20, 1966 

Determination of Dissociation Constant of Hydrogen Cupferrate in Water, Dioxane-Water, and Ethanol-Water Solution

물, Dioxane-물 및 Ethanol-물의 혼합용매에서의 Hydrogen Cupferrate의 산해리상수의 결정
Si-Joong Kim, Chang-Ju Yoon, In-Soon Chang

김시중, 윤창주, 장인순
The glass electrode was empirically calibrated in dioxane-and ethanol-water mixed solvents, by means of which the pH-meter reading could be converted to stoichiometric hydrogen ion concentration. By the potentiometric titration method, the thermodynamic dissociation constants of hydrogen cupferrate (HCup) with variations of ionic concentration in aqueous solution were determined, and by the extrapolation of the constants the new thermodynamic pKavalue, 3.980±0.006, at zero ional concentration was obtained. The thermodynamic dissociation constants of HCup in dioxane-and ethanol-water solution were also potentiometrically determined with the changes in composition of organic solvents at 0.01 and 0.05 of the ionic strength(μ) and 25 ℃. The empirical formula of the constants with mole fraction(n) of the organic solvent are as follow: Dioxane-water solution. pKa= 12.96n + 4.10 at μ = 0.01, n = 0.0228∼0.171 pKa= 12.05n + 4.23 at μ = 0.05, n= 0.0228∼0.171 Ethanol-water solution, pKa= 4.0ln + 4.26 at μ= 0.01, n= 0.0395∼0.262 pKa= 3.83n + 4.34 at μ = 0.05, n= 0.0395∼0.262
114 - 118
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