Abstract
It is well known that individual distribution constants of both cations and anions into diluents contain the equilibrium interfacial potential difference (Δφeq) in their analytic expressions. In the extraction constant of monovalent metal picrates with crown compounds, however, the Δφeq terms were canceled out each other. Accordingly, the extraction constants were expressed as a traditional form without Δφeq. Such results were reasonably explained by the author using the characteristics of the electrochemical potential and a thermodynamic cycle of the overall extraction system.
