Question

A voltaic cell is made with a salt bridge of NaNO₃ and Fe(NO₃)₂ for the anode cell and AgNO₃ for the cathode cell.

a. When constructing the cell, what impact odes the volume of solution in each of the beakers have on the cell potential?

b. If you were to add deionized water to the solution that contains Ag⁺(aq), would this have any effect on the cell voltage? If so, Explain how the cell voltage would change and why.

c. When constructing a cell, you decide to swap the silver rod that is used as a cathode for a copper rod, Cu(s). Will this change have any effect on the cell potential for the operation of the cell? Explain

d. Starting with the original cell, this time you will swap the iron rod used as the anode for a copper rod, Cu. How will this change the affect cell potential and the operation of the cell? Explain.

Answer 1

a. When constructing the cell, the concentration of electrolyte increases in the anodic half-cell, whereas it decreases in the cathodic compartment. Hence, the increase in the concentration of electrolyte ([Fe²⁺]) in the anodic half-cell decreases the cell potential, whereas the increase in the concentration of electrolyte ([Ag⁺]) in the cathodic half-cell increases the cell potential.

b. If you were to add deionized water to the solution that contains Ag⁺(aq), the concentration of Ag⁺ decreases, as a result, the cell voltage decreases.

Explanation: According to the Nernst equation: E_cell = E^o_cell - 0.0591/n Log[Fe²⁺]²/[Ag⁺]). So, as the [Ag⁺] decreases, then the cell voltage does also decrease.

c. When constructing a cell, you decide to swap the silver rod that is used as a cathode for a copper rod, Cu(s), which will not have any effect on the cell potential for the operation of the cell.

Explanation: Similar to Ag⁺/Ag, the cell potential for Cu²⁺/Cu is greater than that of Fe²⁺/Fe.

d. Starting with the original cell, this time you will swap the iron rod used as the anode for a copper rod, Cu(s), which will not affect the cell potential and the operation of the cell.

Explanation: Similar to Fe²⁺/Fe, the cell potential for Cu²⁺/Cu is less than that of Ag⁺/Ag.