Module 5 : Electrochemistry
Lecture 21 : Review Of Thermodynamics
 
The Helmholtz free energy is given by eq.(21.21)
dA = dU - d (TS)
   
  = dU – TdS (at constant temperature) (21.30a)
 
dG = dH –TdS (at constant temperature) (21.30b)

Since (dU) V TdS and (dH)P TdS, eq.(21.30a) and eq.(21.30b) become respectively

 
(dA) T,V 0 (21.31)
 
(dG) T,P 0 (21.32)
The above two equations have extensive applications in chemistry. Note that the equalities apply to equilibria and inequalities in eqns (21.27), (21.28), (21.29), (21.31) and (21.32) apply for spontaneous or irreversible processes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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