ELECTROMOTIVE FORCES IX PYRIDINE 59 



Since the osmotic pressures of the ions are proportional to their 

 concentrations and since for normal electrolytes the concentra- 

 tions are in tnrn proportional to the equivalent conductivities of 

 the solutions, then 



Pi <* t'Q 'i 



P 2 oc 2 C2 



Substituting in (2), we have 



if = '&£• 1 



nf \ 3 c 2 



where c, a and x represent the concentration, the degree of dis- 

 sociation and the equivalent conductance of the electrolyte, re- 

 spectively. 



The temperature coefficients of the electrode potentials were 

 calculated by means of the relation, 



dTf _ TT 86 — Tf U) 



dT TTo '25 ' K } 



The relation between the electrical and chemical energies in 

 a cell is given by the well-known Helmholtz equation, 



r Q T dTT' 

 f dT 



By rearranging and multiplying by .2387 in order to convert 

 joules into calories 



Q=f(Tf-T|^)- .2387 , (5) 



where Q is the heat of ionization. 



By rearranging (1), the solution pressure of a metal is given 

 by the expression, 



. „ 7f nf 



RT + P * 



By substituting for the osmotic pressure p its value calculated 

 from the gas laws, i. e., 



P = 22.4 • - • c -^, 



there is obtained for the solution pressure of the metal, the 

 relation 



lnP^ + In (22.4 • « ■ c ■ ^ ). (6) 



