6.
Measure the potential of the first cell by connecting M
1
to M
2
.
This is done by bringing the positive
terminal or lead of the voltmeter into contact with M
1
(copper) and the negative terminal in contact with
the other metal M
2
.
If the voltage displayed in the meter is negative, then reverse the terminals.
Recall
that the + terminal is the cathode and that reduction takes place there, thus you are measuring
oxidation
potentials
and will need to change their sign to report them as
reduction potentials
in Data Table 2.
7.
With a positive voltage displayed, wait about five seconds to take a voltage reading and record the value
in
DATA TABLE 1
.
Be sure to press down on the metal piece in order to make good contact. Also
record which metal is the positive terminal and which is negative.
Use the same procedure to measure
the potential of the other three cells , M
1
to M
3
, M
1
to M
4
, and M
1
to M
5
, continuing to use M
1
(copper)
as the reference electrode, thus it remains connected to the positive terminal of the voltmeter and
negative voltage readings are possible.
8.
Analyze your data thus far and arrange the five metals from the highest (most positive) reduction
potential to the lowest (most negative) reduction potential.
Metal M
1
(copper) will be assigned an
arbitrary value of 0.00 V since it is used as a reference electrode.
9.
Using the voltmeter,
measure
the potential of the remaining possible
spontaneous
cell combinations.
If
the sodium or potassium nitrate solution has dried (or if any of the other solutions have dried), you may
have to re-moisten it.
Record each
measured spontaneous cell potential
in Data Table 3 and identify
which metal was the cathode and the anode for the
spontaneous
cell.
10.
Calculate
the predicted potentials for the remaining possible
spontaneous
cell combinations and record
each
calculated potential
in DATA TABLE 3.
Show your calculations within the data table.
11.
When you have finished collecting data, use forceps to remove each of the pieces of metal from the filter
paper.
Rinse each piece of metal with tap water.
Dry it and return it to the correct container.
Remove
the filter paper from the Petri dish using forceps and discard it in the trash.
Rinse the Petri dish with tap
water, making sure that you do not touch the chemicals.
