Liquid Junction Potentials Across Aqueous Saturated Calomel Electrode/Some Aquo-organic Solvents Interface

Abstract

The liquid junction potentials (E_j) generated at the boundaries of saturated KCI solution of aqueous saturated calomel electrode [SCE (W)] and mixed aqueous organic solvents have been determined within the framework of tetraphenylarsonium tetraphenylboride (TATB) reference electrolyte extra-thermodynamic assumption. The organic solvents comprise protic methanol (MeOH) and ethanol (EtOH), aprotic dioxane (D) and dipolar aprotic acetonitriJe (ACN), N,N-dimethylformamide (DMF) and dimethyl sulphoxide (DMSO). The E_j values increase almost monotonically in the cases of DMF and DMSO and remain almost invariant till 50 wt % MeOH and EtOH, while in ACN and D, the values lie in between. The contribution to E_j values is mainly from difference of ion-solvent interactions in these mixed solvents, which becomes significant only in the organic-rich compositions.