Liquid junction potential between electrolyte solutions in different solvents: further study on the component related to ion solvation

The liquid junction potential (LJP) between electrolyte solutions in different solvents was studied by paying attention to the component related to ion solvation (component (b)). The actual variation in component (b) was obtained as the variation in corrected emfs (Ecorrected) of a cell and compared with the theoretical values (Ej(b)calc). New data for the Ecorrected − Ej(b)calc relation were obtained using amphiprotic ethylene glycol (EG) and formamide (FA) as solvent on one side of the junctions. The Ecorrected − Ej(b)calc relations at miscible FA/ and EG/organic solvent junctions were nearly linear with average slopes of 0.32 and 0.33, respectively, in contrast to 0.46 for H2O/organic solvents, 0.26 for MeOH/aprotic solvents, and ∼0 between two aprotic solvents. On the other hand, for partially miscible FA/ and EG/nitrobenze (NB), the slopes were 0.70 and 0.84, respectively, approaching unity with the decrease in miscibility. Some factors that may influence component (b) were pointed out and were discussed in detail by considering the phenomena at the junctions. Additional data that support the method to estimate the actual values of component (b) by (slope) × Ej(b)calc were obtained. By appropriate corrections for component (b), the component due to solvent-solvent interactions was shown to be electrolyte-independent also at the junctions containing EG, FA and N-methylformamide on one side.