Dolores RamirezExperiment #5-Determination of an Empirical Formula: The Reaction of Zinc and IodineDolores RamirezChem 2 Lab 2LoganMarch 17, 2013Experiment #5-Determination of an Empirical Formula:The Reaction of Zinc and Iodine1. Introduction: The purpose of this lab is to properly synthesize and purify zinc iodide by reactingelement zinc and iodine; employ mass to determine the empirical formula for zinc iodide. Then we evaluate the validity of the Law of Mass Conservation; and investigate chemical reversibility by decomposing a compound (zinc iodide) back into its constituent elements (zinc and iodine, respectably).1) Experimental:a) Materials:i.20 to 30-mesh granular zinc metal; solid iodine pre-massed (~2 g) samples invials; 6 M acetic acid; ionized water; 5% sodium thiosulfate solutionb) Apparatus:i. 2 boiling tubes or large test tubes (25 x 200 mm); metal test tube clamp; spatula; weigh paper; 10 mL graduated cylinder; desiccator; 9V battery; watchglass; copper-wire electrodes; alligator-clip electrode connectors; Bunsen burner.c) Procedure: 1. Record mass of test tube 1. Transfer 2.0g of 20 to 30-mesh granular zinc metal from glazed weighing paper to the test tube and re-weigh. Record the mass of test tube 1 and zinc.2. Transfer pre-massed iodine to test tube 1. DO NOT SPILL. Record theiodine mass by subtracting the mass of the zinc and test tube 1.3. Add 6 drops of 6 M HC2H3O2 to mL of solution to zinc/iodine solution and swirl for 10 minutes till solution clears up. Record Observations. (color, temp)4. Take the Mass of test tube 2 w/boiling stone and record. Carefully decant warm liquid contents to boiling stone. Do not transfer any solids Zinc particles.5. Next, rinse zinc grains with 1-2mL aliquots of the acidified H2O solution until it is used up and decant into test tube w/ boiling chip.6. Clamp test tube to ring stand. Gently dry zinc and test tube using burner. Swirl occasionally to speed up.7. Dry zinc will flow freely like sand. Allow dry zinc to cool before massing. Determine mass of dried zinc by difference and record.18. Gently heat tube w/ ZnI2 till it evaporates H20 for 25 minutes. DON’TOVER HEAT.9. Briefly allow tube to cool for 3 minutes in desiccator. Determine mass of dried product, tube, stone and record mass of zinc by difference.10. Compare this mass of zinc w/ the sum of masses of zinc and iodine that reacted as determined in pl.11. Do these results confirm the, conservation of mass principal? Record the appearance of the zinc and iodine product. Is the appearance distinctly different from that of zinc and iodine reactants?12. Place a spatula tip of ZnI2 product on watch glass and dissolve with a few mL of ionized H20.13. Electrolyze the solution by placing 2 copper wires electrodes in the, solution; connect w/ alligator-clip wires to either and alligator-clip wires to either and of qv battery for 1-2 minutes. Record observations and find identity of materials formed.3) Results and Discussion:Part 1: Synthesis of zinc iodide- Mass of test tube 1: 21.74g- Mass of test tube 2: 21.68g- Mass of test tube with zinc: 23.54g- Mass of added zinc by difference: 1.83g- Mass of test tube with iodine: 25.73gReactionWhen the solution of water and acidic was first added to the zinc and iodine the solution turned yellow within seconds it the started oozing bloody reddish brown coming from the bottom of the tube where the zinc and iodide were sitting. The temperature rose exponentially making it hot to the touch.- Mass of test tube with BS: 21.96- Mass of BS: .28gPart 2: Isolation of zinc and Iodide- Mass of test tube 1 after reaction: 30.50g- Mass of deducted zinc after drying: 22.92g- Final mass of test tube with zinc iodide: 24.29gAnswers for Questions in Procedure:- Yes, the masses are very similar.- Yes, the zinc was a crystal powder while the zinc was a metal(M unreacted zinc, m zinc in Zn <-> I = total mass of Zn)(Zn is the excess reactant)Part 3: Electrochemical Decomposition of Zinc Iodide2- Started turning brown smelling similar like vinegar- Zn collected on electrode- Iodine appears in solution4) Conclusion:We were able to synthesize pure zinc iodide through reactions and determine the empirical formula through mass. Then evaluate the validity of the Law of Mass Conservation and investigate chemical reversibility by decomposing zinc iodide.a) Initialed Duplicate Laboratory Notebook Page(s):i. The initialed duplicate laboratory notebook page(s) must be included after your conclusion upon report submission.5) Report Questions:- Mass of deducted zinc after drying: 22.92g - Mass of test tube 1: 21.74gZinc used: 1.18g- Mass of test tube with iodine: 25.73g- Mass of test tube with zinc: 23.54gMass I: 2.19g1. Refer to pages 5-6 2. The observation that was made that supports that all the iodide reacted is that there was left over zinc after the reaction. This means that Iodide was the limiting reactant so it was all used up.Zn + I2 -> ZnI23. Refer to pages 5-64. Chemical reactions are reversible. For this reaction, we ran an electric current. In this reaction, we ran an electric current through the aqueous solution ZnI2. This reversed the reaction and created I2 and zinc metal. This was a reversed reaction.ZnI2 (aq) + energy -> Zn (s) + I2 (aq)Product