CARRIERS IN ELECTROLYTIC SOLUTIONS 201 



TABLE LXXXI. 



CALCULATED HYDRATION OF THE IONS FOR DIFFERENT ASSUMED VALUES 

 FOR THE HYDRATION OF THE CHLORIDE ION. 



N Cl N -H. N Cs N K ^Na ^Li 



w w w www 



0.28 0.67 1.3 2.0 4.7 



4 1.0 4.7 5.4 8.4 14. 



9 2.0 9.9 10.5 16.6 25.3 



The assumption that the chloride ion is un-hydrated is improbable, 

 since the conductance of the chloride ion is very nearly equal to that of 

 the potassium ion. The value assumed for the hydration of the chloride 

 ion should therefore differ little from that of the potassium ion. This 

 necessitates assuming for the chloride ion a value not materially less 

 than 4. In all likelihood the true value lies somewhere between 3 and 9, 

 although the true value must necessarily remain uncertain. Below are 

 given the values of the ionic conductance for the different ions at 18, 

 together with the ratio of these conductances to that of the hydrogen ion. 



TABLE LXXXII. 

 COMPARISON OF IONIC CONDUCTANCES AND HYDRATION NUMBERS. 



xrCl xrH ArCs xr-K- xr-Na AT Li 

 1\ I\ I\ IV xv iV 



w w w w w w 



Hydration No 4.0 1.0 4.7 5.4 8.4 14.0 



Ionic Cond 65.5 315. 68.0 64.5 43.4 33.3 



315/A 4.8 1.0 4.6 4.9 7.3 9.5 



It is seen that the values of the ionic conductances relative to that 

 of the hydrogen ion correspond roughly with the values of the hydration 

 of the different ions, assuming the hydration of the hydrogen ions to be 

 unity. An exact correspondence between the hydration and the con- 

 ductance is not to be expected. Nevertheless, except in the case of the 

 caesium and the chloride ions, the order of the reciprocal conductance 

 values corresponds with the order of the hydration numbers. The 

 chloride, caesium, and potassium ions are among the most rapidly mov- 

 ing ions in water, excepting the hydrogen and hydroxyl ions, and it may 

 therefore be concluded that all ions in water are hydrated at least as 

 much as the chloride ion. It is possible, of course, that the hydration 

 numbers may be considerably larger than those assumed on the basis 

 of an hydration of 4 for the chloride ion. How the hydration of the ions 



