Use of Meissners Curves

A technique based upon comparison of osmotic coefficients in order to predict the likelihood of complexing was presented in 1945 by Stokes and Stokes (7). 

They note that the Debye-Hiickel theory relates osmotic behavior to the effective ionic diameter. It would be expected then that species containing the same anions and having cations of similar diameter would have nearly equal osmotic coefficients unless there was a chemical difference between the two. This difference could be interpreted as incomplete dissociation or complex formation. 

There are drawbacks to this method. One is the need for osmotic coefficients for the species of interest as well as for the species of similar diameter. It is also advisable to compare species that would not be expected to form complexes, such as perchlorates or nitrates. And of course, while it may suggest the occurrence of complexes, it gives no clue as to what they may be. 

These methods will now be used to examine specific compounds for complexing behavior. Not all methods wRl be applicable to each compound. Some will, in fact, yield contradictory results. 

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