HETEROGENEOUS EQUILIBRIA 271 



at low concentrations. Salts having a univalent ion in common with a 

 ternary electrolyte cause an initial depression, which, in many cases, is 

 followed by a slight increase in the solubility at higher concentrations. 

 This latter effect, furthermore, is greatly influenced by the properties of 

 the electrolytes involved. The minimum is particularly pronounced in 

 the case of solutions of lead chloride in the presence of lead nitrate. 

 Salts which are only very slightly soluble suffer a much greater depres- 

 sion of the solubility on the addition of a salt with a common ion than 

 do salts of greater solubility. The addition of an electrolyte without a 

 common ion in general causes an increase in the solubility of a ternary 

 salt. This increase appears to vary considerably with the nature of the 

 added electrolyte. In the case of silver sulphate, for example, the in- 

 crease in solubility due to the addition of nitric acid is much greater 

 than that due to the addition of potassium nitrate. 



In the case of salts whose solubility is high, the effect of an addition 

 of various electrolytes depends largely upon the nature of the added salt. 

 In Table CVIII are given the solubilities of strontium chloride in water 



TABLE CVIII. 



SOLUBILITY OP STRONTIUM CHLORIDE IN THE PRESENCE OP OTHER 

 SALTS IN WATER AT 25. 



Equiv. of 



added salt in Sol. equiv. per 



Salt added 1000 g. H 2 1000 g. H 2 



None None 7.034 



Sr(N0 3 ) 2 0.1372 7.044 



0.5766 7.038 



1.0988 7.030 



3.318 6.956 

 Solid Sr(N0 3 ) 2 



NaN0 3 0.3621 7.198 



0.5010 7.270 



3.553 7.276 



6.856 6.844 

 Solid Sr(N0 3 ) 2 



HN0 3 0.1771 7.028 



0.3521 7.034 



1.277 7.034 



HC1 0.1551 6.882 



0.5162 6.502 



1.017 5.996 



2.165 4.864 



9.205 0.530 



