126 



Mineral Nutrition of Plants 



Ion-X NH 4 + NaCl ^ 



Ion-X Na + NH 4 C1, or 



Na Ion-X (NH 4 ) 



= ^ x = 0.793 (experimental) 



NH 4 Ion-X (Na) x 



1 1 



J L 



NaCl 

 NH 4 CI 



Ion XI 



NH 4 

 Na 



NaCl 

 NH 4 CI 



^-—1 NH 4 

 ^ Na 



System X System A 



Figure 8. Device for deriving exchange equa- 

 tions between adsorbents. 



This equation holds for wide variations in the amounts of sodium 

 chloride or adsorbent used. 



The right-hand vessel (system A) contains coarse ammonium-Am- 

 berlite and sodium chloride. The equilibrium equation assumes the 

 form: 



Na Amberlite (NH 4 ) 



= /( A = 0.532 (experimental) 



NH 4 Amberlite (Na) 



Again variations in the amounts of reacting substances do not sub- 

 stantially alter k A . 



Now we open the stopcock and let a new equilibrium be established. 

 Whatever the initial salt concentrations were, we have now: 



(NH 4 C1) X = (NH 4 C1) A and (NaCl) x = (NaCl) A 

 By mere algebraic rearrangement we obtain: 



Na I Ion-X | NH 4 | Amberlite ^ x 0.793 



K = 



1.49, Q.E.D. 



NH 4 I Ion-X Na Amberlite ^ A 0.532 



