38 



HYDROGEN ION CONCENTRATION 



and the dissociation constant is 



[B+] [0H-] 



k = 



[BOH] 



The principles of the apparent dissociation constants apply also 

 in this case as well as for the acids. Here also it is necessary to 

 differentiate between strong and weak bases. The strong bases are 

 the caustic alkalis, such as NaOH, KOH. They are ionized to a 

 great extent, and the exact determination of their dissociation rela- 

 tions is fraught with the same difficulties as in the case of the strong 



acids and will be dealt with later together with them. Also the 

 slightly soluble bases, such as Cu(0H)2, AgOH are probably to be 

 classed with the strong, greatly dissociated bases. The fact that 

 they do not produce in water a marked alkaline reaction is to be 

 attributed exclusively to the slightness of their solubility but not to 

 any lack of dissociation. A base such as AgOH is not known in 

 its free, pure state. But it is highly probable that the traces of 

 Ag20 which dissolve in water go into solution entirely as AgOH, 

 and that the latter is practically completely dissociated, so that 

 actually almost only Ag+ and OH" ions are present in solution. 



