HETEROGENEOUS EQUILIBRIA 



273 



iodate in the presence of different electrolytes in water at 25, as meas- 

 ured by Harkins and Pearce. 33 The results are shown graphically in 

 Figure 56. It will be observed that the solubility of lanthanum iodate 

 is markedly decreased on the addition of a salt with a common univalent 

 ion. The addition of a salt with a common trivalent ion causes a slight 

 initial decrease in solubility, followed by an increase at higher concentra- 



/ 2. 5 4-567 *. 



Equivalents of added salt per 1000 g. water. 



FIG. 55. Solubility of Strontium Chloride in Water in the Presence of Other 



Electrolytes. 



tions. On the addition of a salt without a common ion, there is a 

 marked increase in the solubility throughout. 



While the solubility of different salts is in general affected in a 

 similar manner on the addition of other salts, provided the solubility is 

 relatively low, the interpretation of the experimental results is ren- 

 dered uncertain, owing to the fact that the ionization functions for the 

 electrolytes in the mixtures are not known. At the same time, it is pos- 

 sible that, in the case of salts of higher type, intermediate ions are present 

 as a result of which it not only becomes difficult to take into account 



" Harkins and Pearce, J. Am. Chem. Soc. 38, 2679 (1916). 



