378 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



ductance increases enormously, which result may be accounted for only 

 on the assumption that the speed of one or both of the carriers increases. 

 Since one of these carriers is the normal sodium ion, it follows that the 

 conductance is due to an increase in the speed of the negative carrier. 

 If these conclusions are valid, then, at high concentrations, the conduc- 

 tance of the metal solutions should approach that of the metals them- 

 selves, for at high concentrations the number of carriers and negative 

 electrons present in the solution becomes comparable with that of the 

 total number of molecules present, in which case we should expect that 

 a considerable fraction of these carriers would be free from ammonia 

 molecules. This is borne out by the results of conductance measure- 

 ments. As may be seen from Table CL, the equivalent conductance in- 

 creases from a value of approximately 475 at a concentration of 0.05 N 

 to a value of approximately 2000 at normal and to approximately 82000 

 at a concentration of 2 normal. At this concentration the specific con- 

 ductance of the solution is 163.5, the specific conductance of mercury 

 being 1.063X10*, which is about six times that of the metal solution at 

 the concentration in question. The lower curve in Figure 65 shows how 

 the conductance varies with concentration up to 2 N. 



In the following table are given values of the specific conductance of 

 solutions of sodium in liquid ammonia up to the saturation point of these 

 solutions. 6 



TABLE CLI. 



SPECIFIC CONDUCTANCE OF CONCENTRATED SOLUTIONS OF SODIUM 

 IN AMMONIA AT 33.5. 



V n V \i 



0.1081 5047.0 0.5099 148.3 



0.1331 4954.0 0.7612 20.21 



0.1804 2687.0 0.9265 5.988 



0.2768 1070.0 1.298 1.269 



0.3230 714.0 1.674 0.6465 



The results for sodium, together with those for potassium, are shown 

 graphically in Figure 66, where the logarithms of the specific conduc- 

 tance are plotted against the logarithms of the dilution V as defined 

 above. The curve passing through the points is that of potassium; the 

 other, that of sodium. At the highest concentrations, the solutions were 

 saturated, so that the specific conductance was independent of the total 

 amount of ammonia present. The second point for the value V = 0.1331 



Kraus and Lucasse, J. Am. Chem. Soc. }3 (Dec., 1921). 



