TRANSPORT NUMBER OR TRANSFERENCE NUMBER OR HITTORF NUMBER
We have seen that the different types of ions move with different speeds under the same potential gradient. It therefore, follows that the cations and the anions carry different amounts of electricity during the electrolysis. This current carried by individual ions depends upon its velocity and the total current is constituted by the movement of cations and anions.
“The fraction of the total current carried by a given ionic species in the solution is called the transport number or Hittorf number or transference number. The transport number of cation is represented by e and that of anion by f .”