678 



IONIC RADIUS AND IONIC EFFICIENCY 



remained the same. The rate of diffusion of water was greater in 

 the case of solutions of Nal than in the case of NaBr, and greater in 

 NaBr than in NaCl. Hence the statement is confirmed that when 

 a membrane is negatively charged the rate of diffusion of water 



I 



o 



ti — 







Z40 

 220 

 200 

 180 

 160 

 140 

 120 

 100 



80 



60 



40 



20 

 



jlHillljlJljriMMn 1M9M 



1024 512 256 126 64- 32 16 8 4 2 ^^^ '^^^ 



Concentration of salt solution 



Fig. 4. The same as in Fig. 3 when sokitions are alkaline (pH about 11.0). 

 Order of depressing action of cations on negatively charged membrane Li > 

 Na > K > Rb. 



through the membrane from pure water into solution increases for 

 the anions I, Br, and CI in the order I > Br > CI. 



Since this is also the order of the magnitude of the ionic radius of 

 the three anions, I having the greatest radius, we can say that the 



