182 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



Apparently, when water is added to a solution of hydrochloric acid 

 in methyl alcohol, a complex is formed with water which moves with a 

 much lower speed than does the normal hydrogen ion in pure methyl 

 alcohol. It will be noted that the speed of the normal hydrogen ion in 

 methyl alcohol is exceptionally high. The A values for typical salts 

 in this solvent lie in the neighborhood of 100. The hydrogen ion must 

 therefore move with a speed roughly three times that of the chloride or 

 potassium ion. 



Solutions of hydrochloric acid in ethyl alcohol exhibit a similar 

 behavior on the addition of water. 4 Values of the equivalent conduct- 

 ance of hydrochloric acid in ethyl alcohol in the presence of varying 

 amounts of water are given in Table LXVIII. 



TABLE LXVIII. 



CONDUCTANCE OF SOLUTIONS OF HYDROCHLORIC ACID IN ETHYL ALCOHOL 

 IN THE PRESENCE OF WATER AT 25. 



Mols of H 2 per Liter 

 0.028 0.05 0.1 0.2 0.5 1.0 2.0 3.0 Dilution 



74.2 63.2 58.5 52.6 47.4 42.8 41.8 42.4 44.4 1280 

 35.0 32.0 30.4 27.5 24.2 21.3 21.4 23.3 26.1 10 

 89.4 75.1 69.3 62.0 56.0 50.5 48.5 48.2 49.5 oo 



The conductance curve passes through a minimum for a solution contain- 

 ing approximately two mols of water per liter. This minimum is slightly 

 affected by the concentration of the acid. At lower concentrations the 

 minimum occurs at a slightly higher concentration of water. The shift 

 in the minimum point, following a change in the concentration of the 

 acid, may in part be due to a change in the viscosity of the solution due 

 to the addition of acid. On the other hand, it is possible that the ioniza- 

 tion of the salt is materially affected by the presence of water, particu- 

 larly at the higher concentrations. It may be assumed, however, that 

 at very low concentrations of acid, the ionization is not materially 

 changed due to the addition of water. If this is true, and the acid is 

 highly ionized, the A values should follow a curve corresponding approxi- 

 mately to that of the most dilute solution. In other words, the A values 

 should pass through a minimum somewhere between 1 and 2 normal 

 with respect to water, which has been found to be the case. This indi- 

 cates that the addition of water results in an initial decrease in the 

 speed of the ions up to a concentration of about 2 normal, and there- 

 after in an increase on further addition of water. 



Goldschmidt, Ztschr. f. phya. Chem. 89, 132 (1914). 



