HETEROGENEOUS EQUILIBRIA 



235 



agree at concentrations below 20X10" 3 N. At higher concentrations, how- 

 ever, the freezing point method yields lower values than the conductance 

 method. In the case of potassium iodate, the agreement is not so good. 

 At the lower concentrations the value of the ionization as determined by 

 the conductance methods is about 1.5 per cent higher than that deter- 

 mined by the freezing point method. The limiting value of the conduct- 

 ance of the iodates is much less certain than is that of the chlorides and 

 'nitrates, and it is possible that the ionization values, as determined by 

 this method are in error owing to an error in the value of A . If the 

 value of A were increased by 1.5 per cent, the conductance values for 

 potassium iodate would agree up to a concentration of 0.05 normal. In 

 solutions of sodium iodate, the discrepancies exceed the limit of experi- 

 mental error, of the conductance measurements, at any rate. It is pos- 

 sible that here, also, an error in the value of A would tend to harmonize 

 the results. 



As regards the freezing point of equi-molar mixtures of two electro- 

 lytes, it is interesting to note that the values of i for the mixtures are 

 practically the mean of those for the pure substances at the same concen- 

 tration. 



In Table LXXXVIII are given values of i for salts of higher type, 6 

 together with values of y^ an d Y c where reliable values of Y ar s 

 available. 



TABLE LXXXVIII. 



IONIZATION OP SALTS OF HIGHER TYPE AS DETERMINED BY THE FREEZING 

 POINT AND CONDUCTANCE METHODS. 



CX10 3 i (Hall & Harkins) y- (Hall & Harkins) ~ 



5 



10 



20 



50 



100 



200 



500 



5 



10 



20 



50 



100 



200 



Magnesium Sulphate, MgS0 4 



1.708 

 1.614 

 1.520 

 1.394 

 1.303 

 1.214 

 1.099 



0.708 

 0.614 

 0.520 

 0.394 

 0.303 

 0.214 

 0.099 



Potassium Sulphate, K 2 S0 4 



2.830 0.915 



2.772 0.886 



2.701 0.851 



2.567 0.784 



2.451 0.726 



2.327 0.664 



0.741 

 0.669 

 0.596 

 0.506 

 0.449 

 0.403 



0.905 

 0.872 

 0.832 

 0.771 

 0.722 

 0.673 



Hall and Harkins, loc. cit. 



