 |
 |
9 of 18 |  |
 |
 |
M-9
EXPERIMENTAL PROCEDURE
Before beginning Experiment M, remember to collect your [Ni(NH3)
4
(NO2)2] crystals from the
previous experiment. Please refer to Part B 2. of Experiment L for the procedure.
Part I:
Preparation of standard solutions.
In order to prepare an accurate calibration curve, four standard solutions of the [Fe(Bipy)3]
2+
complex are required. These will be prepared by reacting accurately known volumes of the stock
iron(II) solution with the reagents listed below to form the colored complex. The standard
solutions will be prepared in 100 mL volumetric flasks, so the concentrations can be accurately
calculated.
1.
Set up one buret to dispense the stock iron(II) solution. Using the correct technique
(see p.19) rinse and fill a buret with the stock iron(II) solution.
2.
Prepare standard solution #1.
Using the buret, dispense approximately 15 mL, accurately measured, of the stock
solution into a 100 mL volumetric flask.
NOTE: DO NOT attempt to exactly deliver the recommended volume. Merely read the
buret to 0.02 mL before and after the dispensing of the solution and then calculate, by
difference, the EXACT volume delivered. The concentration of the solution can be
accurately calculated once it is diluted to 100.0 mL at the end of step 3.
Be sure to allow 15 to 30 seconds for the liquid level in the buret to stabilize BEFORE
taking the final buret reading.
3.
In the order given, add the following reagents to the iron(II) solution in the volumetric
flask, mixing the solution after each addition:
2.0 mL of 0.25 M H2SO
4
1.0 mL of 1.0 % hydroxylamine solution
5.0 mL of 0.20 % bipyridine solution
5.0 mL of 1.0 M sodium acetate solution
Allow the solution to stand for 10 minutes and then dilute to the mark with distilled
water. Seal the flask with a cap and mix the solution well, then set aside until required.
