Part B– Measuring Electrode Potentials From your results, arrange these reductions in order of decreasing reduction potential: 1. Get a sample tube and a piece of metal for each of the half-cells listed on the right. Also get one pre-assembled copper half-cell (as shown in the photo on the left below). Half-Cells Zn2*(aq) + 2e Zn(s) 2e Zn2+ | Zn Pb2+ | Pb Sn2+ | Sn Pb2*(aq) + Sn2*(aq) + Cu2*(aq) + Pb(s) Sn(s) Cu(s) 2. Half fill each sample tube with the 1 M solution of the appropriate metal cation. 2e 2e 3. Insert a two holed plastic cap into cach tube and insert the piece of clean metal (Zn, Pb, or Sn) appropriate to the cell into one hole. Each group should have a set of cells as pictured on the right below. Highest (most positive) reduction potential Pb Sn Lowest (least positive) reduction potential Sn2/ 4. Starting with the Zn2+ | Zn half-cell, insert the copper half-cell into the second hole in the plastic cap (as shown in the picture below). Make sure the bottom of the copper half-cell dips well into the solution in the tube. Pb Sn Attach the lead from the VQA terminal of the multimeter to the Cu electrode and the other lead (from the COM terminal on the voltmeter) to the other metal in the cell. Record the voltage produced by the cell. Determine whether the Cu half- cell is the positive or negative electrode. The multimeter shows a positive reading if the electrode connected to the VNA terminal is positive with respect to the electrode connected to the COM terminal. Since you have connected the copper electrode to the VOA terminal, a positive reading tells you that the copper electrode is the more positive of the two electrodes in the cell. Disconnect the multimeter from the cell when you have completed your reading. Make sure you determine the cell voltage and whether the copper half-cell is the more positive before you disassemble the cell. 5. Repeat step 4 for the Pb2+ | Pb and the Sn2+ | Sn half-cells. 6. Disassemble the cells and discard the metal solutions into the heavy metals waste container. Rinse the equipment, including the metals, before returning them to where you got them.