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Licensed Unlicensed Requires Authentication Published by De Gruyter June 2, 2014

Prediction of Dissociation Constants of Ammonium Ion in 20 Mass % Ethanol + Water Mixed Solvent Solutions Containing Sodium Chloride

  • Masunobu Maeda and Chisako Iwata


Dissociation constants of amonium ion (Ka= [H +][NH3]/[NH4+], where [ ] denotes the con­centration) in 20 mass % ethanol + water mixtures with different concentrations of sodium chloride were determined by means of a glass electrode. The dissociation constants in pKa units (on molarity and molality bases) increase linearly with increasing ionic strength. Activ­ity coefficients of ammonia in the ethanol + water mixtures were determined by a transpiration method. The observed dissociation constants on the molality scale were compared with those calculated from the Pitzer equations modified on the basis of the principles of corre­sponding states. The observed values agreed with the calculated ones almost within experi­mental uncertainties.

Received: 1997-9-8
Published Online: 2014-6-2
Published in Print: 1997-11-1

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