Nitration of Cobalt(Iii) Acetylacetonate

4150 Words Aug 13th, 2013 17 Pages
Rossi/Kuwata

Chemistry 222

Spring 2011

Experiment 2: Spectrophotometric Determination of Iron in Vitamin Tablets
(Adapted from Daniel C. Harris’ Quantitative Chemical Analysis and R. C. Atkins, Journal of Chemical Education 1975, 52, 550.)

Experimental work to be done on February 24 + one hour scheduled on your own Notebook due on March 4 (by 4:00 pm ⇒ 20% late penalty each 24 hour period thereafter)

INTRODUCTION
In this experiment, you will dissolve the iron in a vitamin supplement tablet, digesting the cellulosic matrix in the process, and then reduce the iron to Fe2+ with hydroquinone:

While freshly-dissolved aqueous Fe2+ is nearly colorless, we can impart an intense red color by a stoichiometric reaction of Fe2+ with three
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Use them only to draw up reagents, however - disconnect the pump and let gravity drain the pipet. 2. Do not blow out the last bit of liquid from a volumetric transfer pipet! Each pipet is calibrated to deliver its calibrated volume of aqueous sample from the etched line to where the liquid naturally stops draining, with the tip in contact with clean glass. 3. The liquid level in a pipet will change with the depth to which the tip is immersed in liquid. When setting the position of the liquid level even with the mark, the tip of Page 2 of 8

Rossi/Kuwata

Chemistry 222

Spring 2011

the pipet must be out of the solution and touching a vertical glass surface. The same needs to be true as it drains, in order to accurately deliver the required volume. No liquid should transfer on the outside of the pipet, only the inside. 4. If you need to use a wet pipet, be certain to rinse it with whatever you are going to measure with it. Just draw up a pipet full of the liquid you wish to work with and discard it. If the concentration is really critical, perform this rinse a second time. 4. Keep in mind that we are analyzing for Fe…very low concentrations of Fe. Why is using tap water at any point in this process a really, really bad idea? 5. You should sign up online for a one-hour time slot to use the spectrophotometer in 379 OLRI, the

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