EXPERIMENT 10

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EXPERIMENT 10

• Galvanic Cells

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Part A Galvanic (or Voltaic) Cells

• Students work in Pairs.
• Equipment is in a bin at each computer.

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Bring your multiwell plate to the bench in your
section that looks like this and add the required
solutions to the wells. A dropper full of
solution is plenty.
Solutions for the Galvanic Cell part are located
at your TA station.
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Obtain a piece of a string soaked in KNO3 and
place it on a watch glass. Add some saturated
KNO3 solution to keep it wet.
Only one piece of string is required to do all
the voltaic cells. Discard the string when you
have completed todays lab.
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Polish the electrodes every time they are used.
Use the small metal strips (provided in the small
box) for electrodes.
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Attention hold the narrow part of the clip
between your pointer and your middle fingers and
use your thumb to press on the round end of the
clip.
Insert the Cu electrode into the cell containing
Cu2, and the Pb electrode into the cell
containing Pb2, then place the string between
the two cells.
Attach the electrodes to the black and red clips
of the voltage probe.
Connect the voltage probe to the serial box
interface (Port A).
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Read and record the voltage immediately, then
remove the string and return it to the watch
glass of KNO3.
Measure and record the voltage of each cell.
If there is a zero or negative reading swap the
voltage probe clips.
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Attention Indicate on the Report Sheet, which
half cell is the anode and which is the cathode
for each measurement.
Measure the voltage of the following galvanic
cells. Take one reading for each cell.
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PART B Concentration Cells
Empty and clean the multiwell plate, Q-tips are
provided if needed, then start Concentration
Cells.
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Solutions for the Concentration Cells are located
beside the dispensary.
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Cu2 Concentration Cell
Place a dropper full of 0.050 M CuSO4 in one well
and 1.00 M CuSO4 in an adjacent well. Use Cu
electrodes in each cell and measure the potential.
Measure and record the reading for each
Concentration Cell.
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Prepare some PbI2 Combine 3.0 mL of 0.050 M KI
and 1.0 mL of 0.050 M Pb(NO3)2 in a small beaker
(notice the formation of the yellow
precipitate!).
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Use Pb electrodes in both cells.
Pour 1 mL of this PbI mixture into one well and
pour 1mL of 0.050 M Pb(NO3)2 into an adjacent
well of the culture plate.
Measure and record the potential. Calculate the
Ksp of PbI2.
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Determination of the Dissociation Constant of
Cu(NH3)42
Mix 2.0 mL of 0.050 M CuSO4 with 2.0 mL of 3.0 M
NH3 in a small beaker.
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Use Cu electrodes in each cell. Measure and
record the potential of this cell.
Calculate the dissociacion constant of the
complex.
Pour 1 mL of this mixture into a well adjacent
to the 0.05 M Cu 2 well.