Voltaic Cell Reaction Lab

Brianna Cooper
Brandon Boucher
2/16/12

Purpose: To understand how both voltaic and electrolytic cells function.
Procedure: Refer to pages 34-36 of laboratory notebook for experimental details
Results and Discussion: Voltaic Cell Reactions | | | Overall Cell Reaction | Observed Voltage | Theoretical Voltage | Cu2+(aq)+Zn(s) Cu(s)+Zn2+(aq) | 0.947 V | 1.10 V | Cu2+(aq)+Sn(s)Cu(s)+Sn2+(aq) | 0.571 V | 0.473 V | Cu2+(aq)+Fe(s) Cu(s)+Fe2+(aq) | 0.512 V | 0.777 V | Cu2+(aq)+Mg(s) Cu(s)+Mg2+(aq) | 1.598 V | 2.707 V | Cu2+(aq)+Pb(s) Cu(s)+Pb2+(aq) | 0.651 V | 0.463 V |

Concentration Cell | Based on Cu2+ - Cu | Cell Reaction | | [Cu2+] anode | [Cu2+] cathode | Observed Voltage | Theoretical Voltage | 1.0 M | 1.0 M |
In all of these voltaic cells, copper was present as the cathode, and the anode was either Zn, Sn, Fe, Mg or Pb. The electrode with the most positive reduction potential in its half reaction had acted as the best oxidizing agent, or was the most likely to be reduced. For this experiment, copper was the best oxidizing agent, with a reduction potential of +.337 V. Copper was reduced in every reaction, also proving that it was the strongest oxidizing agent. The electrode with the most positive oxidation potential in its half reaction had reacted as the best reducing agent, or was more likely to be oxidized. The best reducing agent in this experiment was Mg, with a oxidation potential of 2.37 V. This was also proven in the experimental results, the reaction between copper and magnesium had yielded the highest voltage. The second part of this experiment had included voltaic cells under non-standard conditions, or 2 copper electrodes were tested with different concentrations of the solutions. At 1.0 M solution for both the anode and cathode, the voltage was read to be 0.00 V. As the concentration of the anode solution changed, voltage of the cell was increased. Although the observed voltage had not matched the theoretical voltage, it followed the same trend of doubling in voltage as the concentration of the anode solution was reduced
The weight of the Zn anode was determined to be 2.2859 g before the reaction and 2.2150 g after the reaction. The weight of the Zn cathode was determined to be 1.9795 g before the reaction and 2.0272 g after the reaction. Mass was lost by the anode and was gained by the cathode. This gain or loss in mass implies that the concentration of the anode solution was increased and the concentration of the cathode solution was decreased as the Zn(s) on the anode had become Zn2+ in the solution and the Zn2+ in the cathode solution became