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Cooper Chung (Yu Cheng) 800736526 Name: Cooper Chung (Yu Cheng) Date: 02/22/12 Lab Partner: Andy Nguyen Kinetics: Concentration Dependence of Reaction Rates Purpose: To determine the rate of the reaction on [OH- ] and to complete the differential rate law in terms of the initial reactant concentration with the order of the reaction. Procedure: Part 1: Order of Reaction with Respect to [phph 2- ] 1. Use a spectrophotometer and set it to transmittance mode. Set it to 0.0. 2. Pour about 10m L of the 0.3 M NaOH solution into a 50 mL beaker and use pipette to transfer exactly 4.0 mL of the solution to your cuvette. Close the sample holder cover and set the transmittance to 100.0. Record the initial transmittance value. 3. Remove the cuvette from the sample holder and add 1 drop of phenolphthalein. Record the absorbance every 5 seconds for 360 seconds. Once 360 seconds have elapsed, data is no longer needed to be recorded. Part 2: Order of Reaction with Respect to [OH- ] 1. Repeat the experiment with a different concentration for [OH- ]. Once you have calculated the m, the order with respect to [phph 2- ], n is able to be solved. For this run, rate will be k obs [phph 2- ] n , where k[OH- ]. 2. Repeat the spectrophotometer if possible and necessary. Pour 5 mL of 0.3 M NaCl solution; this will stabilize the ions in the solution. 3. With a new cuvette, pipet 2.0 mL of the 0.3 M NaOH and 2.0 mL of the 0.3 M NaCl. Add 1 drop of phenolphthalein and record the data each 5 seconds for 360 seconds. Clean up later. Data/Calculations: Phph 2- (Pink) + OH- Phph 3- (Colored) Rate = - [Phph 2- ]/ T = k[Phph 2- ] m [OH- ] n Rate = k[Phph 2- ] m [OH- ] n Part 1 Data Table Every 5 Seconds Absorbance Recorded Every 5 Seconds Absorbance Recorded Every 5 Seconds Absorbance Recorded Cooper Chung (Yu Cheng) 800736526 1 1.00 25 0.718 49 0.498 2 0.945 26 0.708 50 0.490 3 0.940 27 0.698 51 0.482 4 0.930 28 0.688 52 0.474 5 0.92 29 0.678 53 0.466 6 0.915 30 0.668 54 0.458 7 0.905 31 0.658 55 0.450 8 0.895 32 0.648 56 0.444 9 0.885 33 0.638 57 0.438 10 0.874 34 0.630 58 0.430 11 0.865 35 0.620 59 0.424 12 0.855 36 0.610 60 0.418 13 0.845 37 0.600 61 0.412 14 0.835 38 0.592 62 0.404 15 0.825 39 0.582 63 0.398 16 0.815 40 0.574 64 0.392 17 0.806 41 0.564 65 0.386 18 0.796 42 0.556 66 0.378 19 0.788 43 0.548 67 0.374 20 0.778 44 0.538 68 0.368 21 0.768 45 0.530 69 0.362 22 0.746 46 0.522 70 0.356 23 0.736 47... View Full Document

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