TRANSPORT NUMBER

"The fraction of the total current carried in a solution by a given ion. Ions may carry drastically different portions of the total current if their mobilities are different. E.g., in a solution of sodium chloride, less than half of the current is carried by the positively charged sodium cations and more than half is carried by the negatively charged chloride anions because the chloride ions are able to move faster (they have a larger ionic mobility). The transport numbers of the anion and the cation adds up to unity. As a matter of fact, the case when the ions move equally and the transport number of both ions is equal to 0.5 is a rarity. The Hittorf method is an experimental technique for the determination of the transport numbers. Also called ""transference number."" "