Transport Numbers and the Hittorf Method

A solution of lithium chloride was electrolysed for a long period in a cell of two components - a cathode compartment and an anode compartment - separated with a glass frit so that there was transport between the two solutions across the interface defined by the frit (a cell with transport ). Each compartment contained a platinum electrode at the anode, chloride anions were oxidised, whereas at the cathode, water was reduced. 

This transfer is mediated by the passage of an ionic current across the cell. An amount of Cl corresponding to this charge (t- ei) moves from the cathode compartment to the anode compartment at the same time an amount of Li (f+Hel) moves from the anode compartment to the cathode compartment, as shown in Fig. 10.1 for the hypothetical case of tf = 0.75 and t- = 0.25. 

In the anode compartment, f+ ei moles of Li are lost equally ei moles of Cl are consumed by electrolysis, but this is replenished by a current carrying t-Uei moles of Cl , so the overall change in Cl molarity is 

after the electrolysis, the loss of LiCl in the anode compartment corresponds to t neb which is the proportion of the charge passed that is carried by the ionic current of Li+. If this loss is denoted AnLjci, then 

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