Hittorff method

Transport numbers are intended to measure the fraction of the total ionic current carried by an ion in an electrolyte as it migrates under the influence of an applied electric field. In essence, transport numbers are an indication of the relative ability of an ion to carry charge. The classical way to measure transport numbers is to pass a current between two electrodes contained in separate compartments of a two-compartment cell. These two compartments are separated by a barrier that only allows the passage of ions. After a known amount of charge has passed, the composition and/or mass of the electrolytes in the two compartments are analyzed. Erom these data the fraction of the charge transported by the cation and the anion can be calculated. Transport numbers obtained by this method are measured with respect to an external reference point (i.e., the separator), and, therefore, are often referred to as external transport numbers. Two variations of the above method, the Moving Boundary method [66] and the Hittorff method [66-69], have been used to measure cation (tn+) and anion (tx-) transport numbers in ionic liquids, and these data are listed in Table 3.6-7. 

Hildebrand solubility parameter 101 Hittorff method 121 Homer-Wadsworth-Emmons reaction 189... 

Moving Boundary method [68] and the Hittorff method [68-71] have been used to measure cation (tR+) and anion (tx ) transport numbers in ionic liquids, and these data are listed in Table 3.6-10. 

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