CONDUCTANCE OF THE HYDROXIDE ION IN TERT-BUTYL ALCOHOL-WATER AND 1,4-DIOXANE-WATER MIXTURES

Limiting molar conductances Lambda(o), of potassium hydroxide in 2 to 25 mol% tert-butyl alcohol (TBA)-water mixtures were determined at 25 degrees C as a function of pressure up to 196 MPa. Lambda(o)'s of KOH in (2.5 to 15 mol%) 1,4-dioxane-water mixtures at 25 degrees C and 1 a tm were also determined. The excess conductance lambda(o)(E) of the OH - ion estimated as [lambda(o)(E)(OH-) = Lambda(o)(KOH) - Lambda(o)(KCl )] decreased with an increase in the TEA or dioxane content, as did th e excess proton conductance lambda(o)(E)(H+)[lambda(o)(E)(H+) = Lambda (o)(HCl) - Lambda(o)(KCl)]. Although lambda(o)(E)(OH-) is smaller than lambda(o)(E)(H+) at all solvent compositions studied, the rate of dec rease in lambda(o)(E) with organic content is larger for the OH- ion t han for the H3O+ ion in both solvent mixtures except in the water-rich region of TBA-water mixtures. lambda(o)(E)(OH-) increases with pressu re more strongly in TEA-water mixtures than in pure water, and the rat e of increase in lambda(o)(E)(OH-) with pressure has a maximum at 5 mo l% of TEA. These results are discussed in terms of the difference in s tability of hydrogen bonds between the OH- or the H3O+ ion and water m olecules and the increase in repulsive forces due to the orientation [ H-O O-H] of water molecules in the mixtures.