SAFETY NOTES: Normal precautions should be used as when working with any chemical solution.
GENERAL INSTRUCTIONS: Each bench will work as a team to build and test a set of three cells. The class will need to pool their data to complete the entire potential series.
| Part I: Building the Cells | |
 |
Obtain 4 styrofoam cups from the front counter. Cut the tops off the cups so that the cup that remains is ~5 cm deep. |
 |
Obtain a sheet of white cardstock from the front counter and tape the cups to the paper according to the picture to the left. |
 |
Fill the cup in the middle about half full with 0.5M NH4NO3. Label the paper above the cup with the name and concentration of what is in the cup. |
 |
Fill one of the other three cups half full with 0.5M __NO3, one of your assigned metal nitrate solutions. Label the paper to the side of the cup with the name and concentration of what is in the cup. Fill one of the remaining two cups half full with 0.5M __NO3, another of your assigned metal nitrate solutions. Label the paper to the side of the cup with the name and concentration of what is in the cup. Fill the remaining cup half full with 0.5M __NO3, the last of your assigned metal nitrate solutions. Label the paper to the side of the cup with the name and concentration of what is in the cup. |
 |
Obtain 3 filter papers from the front counter and fold them into 1 cm strips. |
 |
Bend one of the strips into a “U” shape. Place one end of the “U” into the center cup making sure that it contacts the solution and then place the other end into any of the other three cups. The filter paper will act as a salt bridge between the three solutions you are measuring. You may need to pre-soak the filter paper strips in NH4NO3 to make sure the salt bridge is functioning properly. Repeat until there is a salt bridge between the center cup and all three of the other cups. |
| Part II: Measure the Potentials | |
 |
Turn on the voltmeter. Set the voltmeter to read volts (V dc). |
 |
Obtain a piece of each of your assigned metals from the front counter. Use sand paper to “shine “ the surfaces of the metal pieces. |
 |
Attach the positve end (red) of the voltmeter to a piece of metal and place it in the correct (matching) nitrate solution so that the metal piece is partially submerged. (DO NOT SUBMERGE THE ALIGATOR CLIPS IN THE SOLUTION.) Use tape to adhere the clips and metal in place if necessary. It is easiest if you simply hold both clips in place. |
 |
Attach the negative end (black) of the voltmeter to another of your assigned pieces of metal and place it in the correct (matching) nitrate solution so that the metal piece is partially submerged. (DO NOT SUBMERGE THE ALIGATOR CLIPS IN THE SOLUTION.) Use tape to adhere the clips and metal in place if necessary. It is easiest if you simply hold both clips in place |
 |
Measure the potential and record it in your lab notebook. If the potential is negative, switch the aligator clips between the metals.
Repeat the potential measurements until a potential is established for each metal combination. Report your findings to the class. |
