Phase-boundary potential across the nonpolarized interface between the room-temperature molten salt and water

The phase-boundary potential across the interface between an aqueous phase (W) and a room-temperature molten salt (RTMS) that is sparingly soluble in W has been theoretically elucidated and experimentally confirmed using potentiometry for the RTMSs, 1-octyl-3-methylimidazolium salts of bis(trifluoromethylsulfonyl) imide and of bis(pentafluoroethylsulfonyl) imide. The phase-boundary potential across the interface is determined by the partition of the cation and anion constituting the RTMS and is little affected by the presence of indifferent electrolytes, such as NaCl in W. The interfaces experimentally studied are of nonpolarized character, in that the phase-boundary potential is nernstian with respect to the activities in W of the ions constituting the RTMS. By changing the concentration of these ions in W, the phase-boundary potential can be varied more than 300 mV. (C) 2003 Elsevier Science B.V. All rights reserved.