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XLVI. The Application of the Law of Mass Action to Strong 

 Electrolytes, and the derivation of the general equation of 

 the ionization isotherm. By William Hughes, B.Sc. 

 (Oxon), M.A.* 



IF interionic forces operative in electrolytic solutions be 

 inverse fijth, and those causing re-formation of mole- 

 cules inverse n 2 th functions of the mean distance apart of 

 the ions, then, as the author has shown (Phil. Mag. [6] xlii. 

 p. 134), 



»i-»a 



2 



(l 



-a V V r^~ x 



where V is the total volume of the solution. r x and r 2 

 denote the same distance ; therefore the assumption that 

 the electrolyte is completely dissociated, made loc. cit., is 

 obviously unnecessary, a is the fraction of the ions which 

 are in the act of forming molecules, and if V is the volume 

 containing one equivalent of the electrolyte, then a > 1. 



The object of the present paper is to derive, on the above 

 assumption of the nature of chemical force, a general rela- 

 tion between V and a, of which the equations of Ostwald, 

 Rudolphi, van't Hoff, and also Partington are special cases. 



Let a volume SVi of solution contain one molecule of a 

 binary electrolyte ; 



.*. NSV 1 = V 1 , where N is Avogadro's Number. 



a may be regarded either as the fraction of molecules 

 ionized, or as what is equivalent, given by the relation 



ry 2 « 2 ' 



where every molecule is regarded as dissociated to an equal 

 extent — i. e., r is the same for each molecule. It follows 

 that r oc a. 



Conductivity experiments show that the ions are practi- 

 cally never too far apart to exert some attraction on each 

 other until infinite dilution is reached ; therefore the last 

 relation holds at all dilutions. 



Now if the ions are separated from each other to the 



* Communicated by the Author. 



