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Week 7: Coordination Chemistry 3 |
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Techniques
In this experiment, you will perform an acid-base titration using a pH meter. You can review the use of the pH meter and titration techniques in the techniques section. Instructions for using an analytical balance and a buret are also given in the site.
Procedure
You will work with a partner this week and share a pH meter. You will both analyze two samples of your own synthesized compound, however. Together, you will perform four titrations.
Prepare two samples of your complex to analyze. The first titration should be done to determine the titration curve, plotting pH as you titrate. The second titration can be done more quickly, to confirm the value of the end point. You will still need to plot the titration curve to determine the end point, but you need not take points as frequently in regions away from the end point.
Weigh about 0.25 g of [Co(NH3)5(H2O)][NO3]3 on an analytical balance. Dissolve it in 75 mL distilled H2O in a 250 or 400 mL beaker. Titrate with the standardized NaOH solution provided, using magnetic stirring, and measuring the pH after each addition of base. Points should be taken most frequently when the pH is changing rapidly, particularly near the equivalence point. Typically 0.50 mL spacing is adequate in the buffer and post-equivalence regions. Points should be taken, however, at 0.1 mL intervals very early in the titration and at 0.05 mL intervals immediately around the equivalence point. Take readings through V2
10 mL.
The experiments for Week 3 are continued in the following section.
You will do preliminary kinetics measurements in Week 3, that will be completed in Week 4. Please continue reading the following section of the manual.
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