Heat of Reaction in an Electrochemical Cell

Let n Faraday charge flows out of a cell of emf E, then

 …….(i)

Gibbs – Helmholtz equation from thermodynamics may be given as

 …….(ii)

From equation (i) and (ii) we get,

where = Temperature coefficient of cell

Case I: When = 0, then 

Case II: When > 0, then  i.e. process inside the cell is endothermic.

Case III: When < 0, then  i.e., process inside the cell is exothermic.