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Electrode potencial

An electrode cell is made from Zn2+/Zn and Cu2+/Cu.
When the conc of Zn2+ is increase the equilibrium shifts forming more Zn. How does this make the electrode potencial more positive?

Reply 1

charco

Study Forum Helper

Original post by Banana ice-cream

An electrode cell is made from Zn2+/Zn and Cu2+/Cu.
When the conc of Zn2+ is increase the equilibrium shifts forming more Zn. How does this make the electrode potencial more positive?

There are two equilibria in the half-cells:

Cu²⁺ + 2e <==> Cu .................... + 0.34V
Zn²⁺ + 2e <==> Zn .................... - 0.76V

When the two half-cells are connected together the cell potential is 1.10V with the electrons attempting to flow from the Zn²⁺|Zn to the Cu²⁺|Cu around the external circuit.

The spontaneous cell reaction is:
Cu²⁺ + Zn --> Zn²⁺ + Cu

The zinc half equation equilbrium is negative showing that the equilibrium tends to the left hand side, releasing electrons. If the Zn²⁺ is increased then this will push the equilibrium to the right hand side making the potential less negative (i.e. more positive)