Calculate the EMF:
Problem: Calculate the EMF of the following electrochemical cell at 25°C:
Answer:
The half-cell reactions are :
R.H.E. 2H+ + 2e- ↔ H2 (g)
L.H.E. Cu (s) ↔ Cu2+ (aq) + 2e-
Overall reaction : Cu(s) + 2H+ ↔ Cu2+ (aq) + H2 (g)
E°cell = E° = E°R - E°L = - 0.34 V
The EMF of the cell is given by,
E = E° -( 0.0591/2) log acu2+ × aH2/(aH+)2 at 25ºc
=- 0.337 -( 0.0591/2) log (0.1) (0.95)/ (0.01)2
= - 0.337 - 0.088 = - 0.425 V