20 



WORK OF C. Al. STLNL. 



By means of the preceding formula the value of X has been calculated for various 

 concentrations used in the mixture of calcium chloride and potassium chloride, and 

 the results are given in table 7. The significance of the symbols has already been 

 given. 



CALCIUM CHLORIDE. 

 Table 7. Hydration of Calcium Chloride in the Mixture. 



T3 

 V 



c 



S 50 1 



I 



u 



tn 



| 30 



u 





 o 



s 



CSJ 



u 



u 



20- 



In order to compare the hydrates formed by calcium chloride in separate solution 

 with those which it forms in the mixture with potassium chloride, the values of M 

 are plotted against the concentrations as abscissas in fig. 1. 



It is seen that while the value of M 

 increases with increase in concentra- 

 tion, in general, in the mixture as in 

 separate solution, M is less in the mix- 

 ture than in separate solution of cal- 

 cium chloride. This is just what we 

 should expect, since there is less water 

 present as solvent in the mixture of 

 calcium chloride and potassium chlo- 

 ride, at any given concentration of 

 the calcium chloride, than there is at 

 the same concentration of the single 

 solution of calcium chloride. It is evi- 

 dent, from previous work, that while 

 the total ?iumber of gram-molecules 

 of water combined increases, in general, 

 with increase in concentration, the 

 molecular hydration decreases with in- 

 crease in concentration. That is, the 

 amount of water with which a molecule 

 of the calcium chloride or the resulting ions combine depends upon the number of 

 molecules of water present to one molecule of the calcium chloride. If, now, instead 

 of increasing the number of grams of salt with hydrating power present in a given 

 solution, and thus diminishing the amount of water, we add to the calcium chloride 

 a substance like potassium chloride and then make up to the former volume, it is 

 evident that, there being less water present, the amount of water with which each 



o 



1- 

 <u 







3 



z 



1 



10 



1 2 3 3.5 



Gram Molecules of Salt per Liter of Solution 

 Fig. 1. 



I. Calcium Chloride Alone. 

 II. Calcium Chloride Mixed with Potassium Chloride. 



