Liquid junction potentials, ion-selective electrodes, and biomembranes

2 11 Liquid junction potentials, ion-selective electrodes, and biomembranes 

If it were possible to have an interface permeable to only one ion, then the transport number of that ion would be unity and 

the corresponding liquid junction potential, is called the membrane potential or Donnan potential. Ideally Em changes in a Nernstian fashion with the activity of the ion in one of the phases, the activity in the other phase being held constant. This is the basis of the functioning of ion-selective electrodes (Chapter 13) and, to a good approximation, of biomembranes (Chapter 17). 

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