Concentration Cell

A concentration cell is an electrolytic cell that is comprised of two half-cells with the same electrodes, but differing in concentrations. A concentration cell acts to dilute the more concentrated solution and concentrate the more dilute solution, creating a voltage as the cell reaches an equilibrium. This is achieved by transferring the electrons from the cell with the lower concentration to the cell with the higher concentration.

Problems

 Calculate cell potential for a concentration cell with two silver electrodes with concentrations 0.2M and 3.0M.

SOLUTION:

Reaction:

Ag2++2e−→Ag(s)

Cell Diagram:

Ag(s)|Ag2+(0.2M)||Ag2+(3.0M)|Ag(s)

Nernst Equation:

E=Eo−0.05922log 0.23.0

  **Eo = 0 for concentration cells

                       E = 0.0644V