M 



THE GENERAL PROPERTIES OF A PERFECT 

 ELECTROCHEMICAL APPARATUS. ELEC- 

 TROCHEMICAL THERMODYNAMICS 



[Gibbs, I, pp. S88-S49; 406-^12] 



H. S. HARNED 



Introduction 



The importance of the contribution of Gibbs to the thermo- 

 dynamics of galvanic cells resides in the exactness, completeness, 

 and simpHcity of his method of treatment. In less than three 

 printed pages, he has set down the complete thermodynamic 

 theory, and has pointed out the fundamental relations between 

 the electromotive force and those basic thermodynamic func- 

 tions which have proved to be of such immense value to subse- 

 quent physico-chemical investigations. 



In the following discussion, the thermodynamics of galvanic 

 cells, so far as explicitly treated by Gibbs, will be developed, 

 both by the use of the general functions and by the method of 

 a reversible cycle. Secondly, the arguments of Gibbs regarding 

 the heat suppUed to or withdrawn from galvanic cells during 

 their charge or discharge at constant temperature will be pre- 

 sented. In a third section, further ramifications of the theory 

 of this subject not explicitly stated, but contained implicitly in 

 Gibbs' general thermodynamics, will be discussed. Finally, 

 the role of Gibbs' fundamental contributions in the subsequent 

 development of the theory of solutions will be briefly outlined. 



I. The General Thermodynamics as Explicitly Developed 



Certain combinations of two or more pairs of electrical con- 

 ducting surfaces in electrical contact constitute a galvanic cell. 

 Not all such cells, however, may be subjected to numerical 



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