Limiting reagent stoichiometry and the mole

Limiting reagent stoichiometry and the mole - Limiting...

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Limiting Reagent, Stoichiometry, and the Mole November 28, 2007 Chemistry 1 Lab Course 2207 Hsiang-Ting Ko Kelsey Lynch, Victoria Giordano, Robert Marach
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Purpose: The purpose of this experiment is to be able to determine a formula for a reaction using the information obtained from the experiment. In other words, macroscopic properties are calculated and related to actual chemical structure. The goal of this experiment is to be able to find a limiting reagent through calculations involving the mole as well as being able to graph information and use the results to calculate a stoichiometric value to be used in creating a chemical formula. Procedure: This experiment calls for two different methods. One is the mole-ratio method and the other is Job’s method. Both are two different approaches to finding the value of “n” the stoichiometric value that needs to be solved for in the chemical formula. The reaction used in this experiment was Reaction #6. C 15 H 11 N 3 was reagent 1 and Fe(NH 4 ) 2 (SO 4 ) 2 was reagent 2. The mole-ratio method was performed first by Robert and Kelsey. Obtain 15 test tubes and label them. A 100 mL buret must be used to add the volumes that will follow. Add 2.5 mL of reagent two to each of the 15 test tubes. The target concentration of reagent two is 1.0 x 10^-3 M in the experiment. To obtain this morality, .0392 grams of reagent two must be added to the 100 mL buret of water (calculation shown in demonstrated calculations). Then add .3, .7, 1.2, 1.8, 2.3, 2.6, 3.0, 3.4, 3.7, 4.3, 4.8, 5.6, 6.1, 6.7, 7.2 mL of reagent 2 to test tubes 1-15 respectively. A 100 mL buret must be used to add these volumes. Proceed to place each test tube into the spectrophotometer and record its Absorbance (A). Wipe the tubes clean from fingerprints and make sure to zero the spectrophotometer before the first use. Afterward, similar steps are repeated for Job’s Method, performed by Victoria and Kelsey. However, both reagents are then added at different volumes but the sum is kept at a constant 6.50 mL. Add 6.50, 6.0, 5.6, 5.1, 4.5, 4.0, 3.5, 3.2, 3.0, 2.5, 2.0, 1.4, 0.9, 0.5, 0.00 mL of reagent one to test tubes 1-15 respectively. Then add the correct amount of reagent two to each test tube so that the volume in each tube is 6.50 mL. Again, place each test tube into the spectrophotometer and record the absorbance that was measured. Data, Graphs and Results: Mole Ratio Method Trial # Volume   of  R1 (L) Volume   of  R2 (L) Moles R2 A (absorbance) A 1 0.0025 0.0003 0.0003 1.066 2 0.0025 0.0007 0.0007 0.965
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3 0.0025 0.0012 0.0012 0.840 4 0.0025 0.0018 0.0018 0.723 5 0.0025 0.0023 0.0023 0.716 6 0.0025 0.0026 0.0026 0.596 7 0.0025 0.0030 0.0030 0.576 8 0.0025 0.0034 0.0034 0.532 9 0.0025 0.0037 0.0037 0.507 10 0.0025 0.0043 0.0043 0.469 11 0.0025 0.0048 0.0048 0.445 12 0.0025 0.0056 0.0056 0.403 13 0.0025
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Limiting reagent stoichiometry and the mole - Limiting...

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