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R-12
procedure to measure the voltage of this half-cell against the 1.00 M reference solution and record the
value. Repeat this procedure using the other two test solutions, remembering that we will assume a
value of 0.000 V for a 1.00 M AgNO3 test solution. Save the test solutions for use in Part II.
Part II: The Determination of an Equilibrium Constant
In the same circle around the KNO3 used in Part I, fill another well approximately 2/3 full with 1.00 M
Cu
2+
solution and connect it with a piece of filter paper to the KNO3 solution. Put a copper electrode
into this solution. Then, using this half-cell as the reference, determine the cell potentials using each of
the Ag
+
solutions from Part I as test half-cells. Again begin with the most dilute silver solution.
Record your results in the table for Part II on the Observations Sheet.
Part III: The Determination of a Solubility Product
Your instructor will assign to you a volume of 1.00 M NaOH to be combined with
1.00 mL of 0.10 M CuSO
4
in a 13 x 100 mm test tube. Record the concentration and the volume of the
NaOH reacted on your Observations Sheet. Mix the reaction solution thoroughly then transfer part of this
reaction solution with a small amount of precipitate into a well in the 24-well plate adjacent to the
reference 1.00 M CuSO
4
half-cell. Put a strip of Cu
(s)
in this test solution to serve as the electrode. Use a
filter paper strip as before to form a salt bridge from this solution to the KNO3. Measure the cell
potential and record the value on your Observations Sheet.
Part IV: Determination of a Formation Constant, K
f
(also called a stability constant Kst)
Your instructor will assign to you a volume of 1.00 M NH3 to be combined with 1.00 mL of 0.100
M CuSO
4
in a 13 x 100 mm test tube. Record the concentration and the volume of the NH3 reacted on
your Observations Sheet. Mix the reaction solution thoroughly then transfer part of this reaction solution
into a well in the 24-well plate adjacent to the reference 1.00 M CuSO
4
half-cell. Put a strip of Cu
(s)
in
this test solution to serve as the electrode. Use a filter paper strip as before to form a bridge from this
solution to the KNO3. Measure the cell potential and record the value on your Observations Sheet.
Before leaving the laboratory, check to make sure that all of your equipment is clean, and in
your drawer. As well, all communal equipment must be clean and returned to the designated location in
the laboratory.
