1489 
e. Solution of the metal by withdrawal of metal ions. 
We have shown here that a metal will dissolve when electrons 
are withdrawn from the homogeneous equilibrium : 
ae E ¢ 
. MM" +20 
Of course the same thing happens when we succeed in diminish- 
ing the concentration of the metal ions MZ. For this purpose we 
should have to try to add a substance which yields a complex with 
the ion MZ”, the dissociation constant of which is exceedingly small. 
It will be discussed later whether this is possible. 
4. New relations for the potential difference metat-electrolyte. 
If in the derivation of the potential difference metal-electrolyte we 
take into account the ionisation equilibrium in the metal and in the 
coexisting electrolyte, we get what follows. 
For the simplest case for unary behaviour the equilibrium 
Mee MeeOsi ioe a me eee 0) 
will prevail in the metal; the following corresponding equilibrium : 
Mr Mr POG wo Ar e's ee old) 
in the coexisting liquid. 
The equilibrium between metal and electrolyte can now be repre- 
sented by: 
Ms 2 Ms +65 
th —Mit+ 
but this equilibrium is as a rule accompanied with a potential 
difference. 
For this potential difference ‘we now get, in contrast with the 
earlier view, the (vo following equations: 
EE) 
and 
A) 
In the first place we have therefore a relation (12), in which 
occurs the difference between the molecular potentials of the metal 
ion in the metal and in the solution, and in the second place a 
similar relation (18), in which instead of the molecular potentials of 
the metal ion, those of the electrons occur. 
