Chem Lab Three_rev - Chemistry Lab Number Three

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Experiment Three - Determination of Chemical Formulae: The Reaction of Zinc and IodideBy:NikitaLab Instructor: Rachna KhuranaSeptember 22, 2009
Purpose:The purpose of the following experiment is to synthesize and purify zinc iodide by combining granular zinc metal with elemental iodine dissolved in a slightly acidic aqueous solution; additionally, the goal remains to employ relative mass to determine the empirical formula of zinc iodide and confirm the validity of the Law of Conservation of Mass. Observations and Data Tables:Part 1: Synthesis of ZincProcedure and Observations:The zinc was granular and silvery in color; it also exhibited a shine. The iodine crystals were granular and dark gray in color. These substances were massed and then placed into a test tube. The masses are noted in Table 1A. Upon the addition of the acidified water solution (10 mL water with 6 drops of 6 M acetic acid) into the test tube containing zinc and iodine, the mixture turned a dark reddish brown/black color. It began to bubble and gave off a great deal of heat. As the solution was mixed for 10 to 15 minutes using a stirring rod, it became gradually more and more translucent, going from a dark brown/black color to a reddish color to yellow and finally to clear. The fact that the solution turned clear indicated that the reaction had been completed. Table 1A: ObjectMass (grams)Test Tube16.403 Zinc1.930Test Tube and Zinc18.325Iodine Crystals2.082Test Tube, Zinc, and Iodine Crystals20.403Table 1B: ObjectMass (grams)Large Test Tube44.36 Large Test Tube and Boiling Stone44.52Note: This information was set aside for use in Part 2 of the experiment.
Procedure and Observations: Upon completion of the above reaction, the resulting clear liquid (the product, zinc iodide) was decanted into the large test tube containing a boiling stone indicated in Table 1C. The zinc granules that remained at the bottom of the test tube were rinsed three times with 1 mL aliquots of the acidified water solution. These washings were also decanted into the test tube containing the boiling chip. The zinc was then dried via the use of a Bunsen Burner. During this

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