Bjerrum relation coefficients

The effect of added salts on the rate constant of a given ionic reaction has been studied for many years. The Br nsted-Bjerrum treatment of these salt effects has been particularly successful, the rate constant being related to the ionic strength of the solution. The observed trends can be quantitatively accounted for using the DHLL or a related expression for the activity coefficients of reactants and transition state. This subject has been reviewed in detail (Perlmutter-Hayman, 1971). The ionic-strength principle appears satisfactory when the reaction involves ions of opposite charge but less so when it involves ions of the same charge. 

The practical osmotic coefficient obtained directly from cryoscopic measurements gives a measure of the deviation from ideality for the solvent species. The corresponding measure of deviation from ideality for the solute species is the activity coefficient, y. y and (f> are related as a consequence of the Gibbs-Duhem equation. The following expression was first derived by Bjerrum ... 

---