

OTHER PROPERTIES OF ELECTROLYTIC SOLUTIONS 307 



the energy change in the case of hydrochloric acid is opposite from that 

 of sodium and potassium chlorides. 



Earned has also determined the energy changes accompanying the 

 transfer of hydrochloric acid from solutions containing hydrochloric acid 

 of concentration 0.1 N, together with an added salt having a common 

 chloride ion at varying concentrations, C, to a solution of pure hydro- 

 chloric acid at a concentration of 0.1 N. The results are given in the 

 following table. 



TABLE CXXVII. 



ENERGY CHANGE ACCOMPANYING THE TRANSFER OF Two MOLS OF HC1 FROM SOLUTIONS 

 OF 0.1 N HC1 + CN MCI TO A SOLUTION OF 0.1 N HC1 AT 25. 



KC1 



C 05018 0.5086 1.0346 2.134 3.309 



AH 6 37 149 1371 2807 



NaCl 



C 0.1003 0.2014 0.5061 0.9183 1.023 1.871 2.094 2.711 3.202 3.726 



AH 44 142 273 569 755 2373 2381 3595 4647 5942 



LiCl 



C 0.8485 1.7267 2.636 3.574 4.556 



A# 1407 4128 6527 9200 11610 



It will be observed that the energy change is greatest for LiCl and 

 least for KC1. Apparently, the energy change is greatest for those salts 

 which exhibit the greatest tendency to form hydrates. These energy 

 changes persist below 0.1 N. This is apparently also the case in solu- 

 tions of the pure electrolytes. 39 



7. Change of the Transference Numbers at Low Concentrations. 

 The transference numbers of an electrolyte are determined by the rela- 

 tive speed of its ions. Any influence, therefore, which tends to alter the 

 relative speed of the ions obviously tends to alter the transference num- 

 bers of the electrolyte. The speed of the ions is a function of the vis- 

 cosity of the solution and, for a given change of viscosity, the change in 

 the speed of an ion depends upon the nature of the ion. This, for 

 example, is evident from the effect of temperature on the ionic conduc- 

 tances, where, as we have seen, the temperature effect is the smaller the 

 greater the conductance of the ion. At higher concentrations, therefore, 

 where the viscosity effect is appreciable, a change in the value of the 

 transference numbers is not unexpected. 39 * At low concentrations, how- 

 ever, we should expect the transference numbers to be constant. 



This condition is apparently not fulfilled in solutions of strong acids 

 and bases. For example, the anion transference number of hydrochloric 



39 Compare Ellis, loc. cit. 



3 " It has been found that the transference number of lithium chloride is not altered 

 on the addition of raffinose (Millard, Thesis, Univ. of 111. (1914)). Reference to Table 



