A study of the equitransference level of concentrated aqueous rubidium bromide, rubidium iodide and ammonium iodide and their characterization as ultra-concentrated salt bridges for the minimization of liquid junction potentials

Ion and solvent transference nos. for aq. RbBr, RbI and NH4I solns. were detd. at molalities up to 5.5, 6.5 and 7.5 mol/kg, resp., from emf. measurements on appropriate transference cells. For the minimization of liq. junction potentials, all the 3 salts above are better salt bridges than the popular satd.-KCl, both because they are more nearly equitransferent (over the whole molality range) and because they can reach satn. molalities (7.01, 7.38 and 12.69 mol/kg, resp., at 25°) much higher than that of KCl (4.804 mol/kg). Therefore, concd. RbBr, RbI and NH4I solns. can be recommended as advantageous salt bridges for replacement of KCl.