Calculate the electrode potential:
Problem:
A platinum electrode is immersed in a solution which is 10-1 M in KMnO4 and 5×10-4 M in MnSO4. Calculate the electrode potential at 25oC for pH zero (Eo MnO- /Mn2+ =1.51V).
Answer:
At pH= 0, the half cell-reaction is
MnO - + 8H+ +5e ↔ Mn2+ + 4H2O
Write Nernst equation, to evaluate, the electrode potential
E = Eo + (0.059/5) log [MnO-4 ] [H+ ] 8/ [Mn 2+ ]
= 1.51 +(0.0591/5) log(10-1 × 18/5×10-4)
=1.51+ 0.0591/5 log 2×102
=1.51+ 0.0268
=1.537 V