Effect of concentration on electrode potential

state and explain what would happen to the value of the electrode potential of a half cell if the concentration was decreased

Reply 1

charco

Study Forum Helper

The electrode potential depends on the equilibrium (for example)

M(s) <==> M2+(aq) + 2e

The further the equilibrium is to the right the more negative the electrode potential.

By the equilibrium law:

Kc = [M2+]

M(s) cannot appear in the equilibrium law equation as it's not in the same state.

Therefore an increase in concentration must cause the equilibrium to move to the left hand side making the electrode potential more positive. And a decrease in concentration must have the opposite effect i.e. make it more negative.

This is in line with Le Chatelier's principle.

Reply 2

lil'p

so if M2+(aq) + 2e <==>M(s) was the reduction reaction

then a decrease in conc of M2+ cause equil to shift to right

makin more negative electrode potential?