An electrochemical cell is based on the following two halfre

An electrochemical cell is based on the following two half-reactions: Ox: Pb(s) - Pb2+(aq, 0.15M ) + 2e- Red: MnO-4(aq, 1.50M) + 4 H+(aq, 3.0M) + 3e- rightarrow MnO2 (s) + 2 H2O (l) Compute the cell potential at 25 degree C.

Solution

Ecell = Eo - 0.0591/n *log K

here n = 6 electrons which is involved in the complete balanced reaction.

K = [Pb2+ (aq)]^3 / [MnO4-(aq)]^2 * [H+(aq)]

   = 2.286 * 10^-7

so

1.56 = Eo - 0.0591/6 * (-6.6408)

1.56 = Eo + 0.06541

Eo = 1.56 - 0.06541

     = 1.4945 V