Liquid Junction Potential between Electrolyte Solutions in Different Solvents: Some Consideration on the Component Due to Solvent–Solvent Interactions

• Published in: Bulletin of the Chemical Society of Japan Vol. 83; no. 1; pp. 39 - 41
• Main Author: Izutsu, Kosuke
• Format: Journal Article
• Language: English
• Published: The Chemical Society of Japan 2010
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.20090225

The liquid junction potential between different solvents contains three components, i.e., (a) related to ionic concentrations and mobilities, (b) related to ion solvations, and (c) related to solvent–solvent interactions at the junction. In order to understand the characteristics of component (c), we formerly introduced a model that the two solvents at the junction directly interact each other as a Lewis acid and a Lewis base and some parts of the solvent molecules are oriented perpendicularly to the boundary. However, this direct-interaction model deviates from reality in that the actual junction has a transition layer; its solvent composition gradually varies from that on one side to that on the other and its thickness expands with time, usually between 0.05 and 1 mm. In this report, we show that this direct-interaction model is applicable also in the presence of such transition layer. For this, we divide the transition layer in steps and get the total component (c) by summing up component (c) at each step. Here, the value at each step is obtained from the experimental results for component (c) at mixed solvent/mixed solvent junctions. The extent of the solvent orientation at the boundary was also roughly estimated.