GIANT ELECTROPHORETIC EFFECTS AND THE UNUSUAL CONCENTRATION-DEPENDENCE OF THE HEATS OF TRANSPORT OF DILUTE AQUEOUS TETRABUTYLAMMONIUM SALTS

Ion-ion interactions are known to cause the heats of transport (Q*) of dilute electrolytes to drop rapidly as the concentration increases. Aqueous solutions of tetrabutylammonium salts present interesting exceptions to this rule. For these systems Q* falls to a minimum near 0.002 mol dm-3 and then increases with the concentration. Moreover, the values of Q* are not additive. Calculations suggest that the unusual concentration dependence of Q* for aqueous tetrabutylammonium salts arises from exceptionally strong ion-solvent electrophoretic interactions, which outweigh the ion-ion interactions.