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Lecture Room Volt Meter


  • 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





Voltage Observed

(-) (+)
Lecture Meter Fluka Meter Literature*
Zn Cu
1.1 1.091 1.0998

0.6 0.599 0.6368

Pb Zn
0.6 0.599 0.6368

-0.5 -0.488 -0.463

Cu Zn
-1.1 -1.091 -1.0998

-0.5 -0.488 -0.463

*Quantitative Chemistry, Jurg Waser