682 



IONIC RADIUS AND IONIC EFFICIENCY 



ion concentration of the solution inside the collodion flask and the 

 water surrounding the collodion flask had therefore the same hydrogen 

 ion concentration of about lO^^ n. Fig. 6 shows the order of influence 

 of different cations upon the rate of diffusion of water through the 

 membrane into the solution. The anion is always the same; namely, 

 CI. The order of efficiency of the cation series increases in the order 



I 



to 



00 



200 



180 



160 



140 



120 



100 



80 



60 



40 



20 







1024 512 256 128 64 32 16 8 4 z ^^^ ^^^ 



Concentmtion o| salt solution 



Fig. 7. The same order of efi&ciency of cations if the anion is NO3. 



Rb < K < Na < Li; i.e., the efficiency of monovalent, monatomic 

 cations increases inversely with the magnitude of their radius. This 

 order is the same regardless of the anion. Thus Fig. 7 shows that 

 the order is the same when CI is replaced by NO3. 



The anion depresses the rate of diffusion of negatively charged 

 water through the membrane into the solution when the membrane 

 is positively charged. Fig. 8 shows that this depressing eft'ect of 



