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Lecture Room Volt Meter
Procedure
- Cut wedges out of a piece of 9cm filter paper so that three equal spokes
~1cm wide are left (should look like a 'Y'). Cut the tips off so the 'Y'
fits into the dispo petri dish. .
- Place 2-3 drops 1M CuSO4 at one end of the 'Y', repeat with
1M ZnSO4, and 1M Pb(NO3)2. The solutions
will start to wick along the paper. Before they merge add 1-2 drops 1M Na2SO4
(salt bridge) to the center of the 'Y' to stop the wicking. .
- Position 1cm2 pieces of Zn, Cu, and Pb over their salts at
the tips of the 'Y'. .
- With the meter set on center zero, measure the voltage. Switching leads
shows direction of electron flow. Be sure the 3V module is in place.
| Reactions |
E (volts) |
| Cu2+ + 2e- --> Cu (s) |
0.337 |
| Pb2+ + 2e- --> Pb (s) |
-0.126 |
| Zn2+ + 2e- --> Zn (s) |
-0.7628 |
| Lead |
|
|
|
Voltage Observed |
|
|
| (-) |
(+) |
|
Lecture Meter |
Fluka Meter |
Literature* |
| Zn |
Cu |
|
1.1 |
1.091 |
1.0998 |
|
| PB |
|
0.6 |
0.599 |
0.6368 |
|
| Pb |
Zn |
|
0.6 |
0.599 |
0.6368 |
|
Cu |
|
-0.5 |
-0.488 |
-0.463 |
|
|
| Cu |
Zn |
|
-1.1 |
-1.091 |
-1.0998 |
| |
Pb |
|
-0.5 |
-0.488 |
-0.463 |
*Quantitative Chemistry, Jurg Waser
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