QS Study

The Transference number of ions varies with the change of concentration; such changes are quite complicated and the extent of change is also small. Transport number also depends on the temperature; t+ usually increases slightly with rising in temperature. The anion transport number, therefore, generally decreases with the increase of temperature. In Table, the transport numbers of some cations are given.

Table: Cation Transport Number at 20°C

For the same cation or the anion, the transport number depends on the electrolyte. Thus t+ values for K+ in KCl, KBr, and KNO3 are 0.490, 0.488 and 0.508 respectively. Similarly t values for Cl in HCl, LiCl, NaCl and KCl are 0.177, 0.662, 0.605 and 0.510 respectively. This is easy to understand because the transport number is not a unique property of the ion but depends on the relative speeds of the cation and anion in an electrolyte.

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