Studies on the Bi-ionic Potential and the Mobility Ratios with Resin-membrane Electrodes and Their Behaviour in a Mixture of Critical Ions

The 'mobility ratios' in resin membranes for a number of ion pairs, viz., Na+-K++,I-—Br–, Br--Cl-, NO3--Cl–, and NO3--Br–, have been calculated from measurement of bi-ionic potential observing at the same time the influence of ionic strength on them. The 'mobility ratio' values of different resin-membrane electrodes arc not as widely different for a pair of ions as would be desirable for a satisfactory evaluation of the unknown activities in a binary mixture of critical ions using Marshall's equation. The behaviour of resin-membrane electrodes towards a mixture of critical inns has been studied with K+—Na+,Br--NO3–,-Cl- and NO3,--Br–mixtures with a activity ratios varying from 100 to 1 to find the influence of the second ion on the membrane which hen been initially saturated with the first ion on both eider. The second ion begins to affect the E.M .F. ea soon as its activity id above a certain value which has been found to be different for different ion pairs