510 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
side only the formation of one equivalent of lithium chloride 
from the silver chloride and lithium amalgam electrodes. On 
the concentrated side there is transferred to the electrodes from 
the solution one equivalent of lithium chloride. The free energy 
accompanying this change is, 
E, F=RT loge— (2) 
a 
Combining equations (1) and (2) we arrive at an expression 
for calculating the transport number of the cation directly from 
the electromotive force measurements : 
Nc = 
E 
E x 
( 3 ) 
All cells on closed circuit tend to operate until the activities 
of the two solutions become equal. In cells without transference 
such an equalization by direct diffusion of the molecules and 
ions is impossible. The same result is obtained, however, by 
the formation of the salt from the electrodes on the dilute side 
and the simultaneous removal of the salt to the electrodes on 
the concentrated side. It is obvious, therefore, that the free 
energy of dilution of lithium chloride is equal to the sums of 
the free energies of dilution of the separate ions, i. e., 
^ ^ a" (LiCl) a” Li + ' a” Cl" 
E r • F - RT log e (LiCl) ~ RTloge a < Li + • a > C p 
Assuming that a'' li'A == o!’ ci- and that a! llA =a' ci‘, Then for 
the chloride ion, 
E r F = 2RT lo£ 
a Cl* 
a GI- 
RT logf 
a (LiCl) 
a’ (LiCl) 
( 4 ) 
The well known relation of Nernst makes possible a calcula- 
tion of the electromotive force from electrical conductivity data. 
For cells involving transference, 
E = 2 N, 
RT 
*"N” 
c F loge a' N 
and for cells without transference. 
RT 
A N” 
E^a-jrloge yN , 
( 5 ) 
( 6 ) 
The ratios of the activities of the ions and of the undissociated 
molecules are readily obtained from equation (4). The con- 
