Concentration Cells

The cell potential of a redox reaction depends significantly on the concentration of the reactants and products.

Consider a nickel-silver galvanic cell under standard conditions with a cell potential of 1.03 volts. A change in concentration, however, can either increase or decrease the cell potential.

If a concentration gradient influences a cell potential of two different half-cells, can it be used to construct an electrochemical cell with identical half-reactions?

Consider a galvanic cell with two identical silver electrodes, each put in a solution containing a different concentration of silver ions. This set-up is called a concentration cell.

Following Le Châtelier's principle, the concentration gradient drives the electron flow spontaneously from the half-cell with the lower ion concentration to the half-cell with the higher ion concentration. Thus, oxidation occurs in the more dilute cell, where the silver electrode is oxidized, forming silver ions, whereas in the more concentrated cell, silver ions are reduced to solid silver.

The cell potential of a concentration cell is therefore determined solely by the concentration difference of the chosen redox reagent and can be calcul