( ^) 



+ 



de 



V6 



which increase is negative, because fi-„ > [i^n • 



111 the virtual displacement of the quantity of electricity de 

 from the metal towards the solution the change of the thermodyna- 

 mic potential is not the only one that has taken place during this 

 process. 



If we call the electric potential of the solution Ve and that of the 

 zinc V„t , we know that in the above case I"c ]> Vm and Ve — V,,, = ^ 

 indicates the potential diiference of the electrolyte and the metal. 

 With the virtual displacement of the quantity of electricity de from 

 the metal to the electrolyte this quantity has undergone an electrical 

 potential increase A, and so the electric energy has increased 

 with A de. 



From the principle of virtual displacement follows that with electro- 

 motive equilibrium 



+ 



^'''~^''" de-i-Ade = 0, (1) 



V e 



or 



+ 



^ ^ _ i^lfl^J^ (2) 



V 6 



Now we know that the inol. thermodyn. potential of a substance 

 may be S[)lit up as follows : 



(1= ft' -f/i; Tin C 



where in diluted states of matter ft' may be called a function of 

 the temperature alone. 



In non-diluted states however, (i depends also somewhat on the 

 concentration. 



If we now apply this splitting up also to equation (2), we get : 



. _ (li'.n-(Xzn)-{-RT ln C 



where C represents the concentration of the Zii-ions in the electrolyte. 

 If we now put : 



•4- 



ii.n-ll'.n ^^^^^ 



RT ^ ^ 



we may say of this K that for diluted states of matter it will only 



