Consider a galvanic cell constructed from standard copper and zinc half-cells. If a concentrated aqueous solution of ammonia is added to the copper half-cell compartment, what will be the effect on the overall electromotive force of the cell?

💡 Solution & Explanation

Adding ammonia forms a stable tetraamminecopper(II) complex, which drastically lowers the concentration of free copper ions in the solution, shifting the reduction potential of the copper half-cell to a more negative value and reducing the net cell potential. Nernst equation quantitatively relates cell potential to ion concentrations. Complex formation is common among transition metal ions.