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bleachlab - Bleach Kinetics PURPOSE The purpose of this lab...

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Bleach Kinetics PURPOSE The purpose of this lab is to study and gain experience with kinetic reactions and rates through  the analysis of the reaction between organic dyes and sodium hypochlorite via spectroscopy. Kinetic  studies are important because it shows evidence of the mechanisms of chemical reactions. Kinetics  also shows how different conditions affect speed of reactions. This means that chemists can use  kinetics to decide which methods are the most effective for producing certain chemical compounds. PROCEDURE In the first part of the experiment, 2.5ml each of blue, red, and yellow dye were obtained. Using  a spectrometer, data for a blank of distilled water was collected. Then, setting the mode to standard,  type of data collection to spectrum/peaks, and wavelength range to 350-700nm, 2.5 ml of each of the  blue, red, and yellow dyes were run through the spectrometer one at a time.  In the second part of the experiment, 0.1 ml of bleach were added to 2.5 ml of each dye in  cuvets and the reaction was observed with the naked eye. The approximate time required for each dye  to turn clear was observed. These cuvets were then run in a spectrometer with the same settings as  above to test for any interfering absorbances. In the third part of the experiment, the spectrometer's settings were changed to kinetics mode  and the same procedure as the second part of the lab was repeated. 2.5ml of each dye was reacted  with 0.1 ml of bleach in cuvets and the cuvets placed immediately in the spectrometer after the addition 
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of bleach. In the case of yellow dye, the bleach was added after the cuvet with the dye was already  placed in the spectrometer. Each dye was run with different wavelengths according to the wavelength  obtained in the first part of the experiment. In the fourth part of the experiment, the concentration of bleach was halved before adding 0.1  ml to 2.5 ml of each dye. The same procedure as in three was repeated under the same settings. In the fifth part of the experiment, a green dye composed of the yellow and blue dyes was  tested at 5 o C and 40 o C. The same settings for the spectrometer as in the previous steps were used. RESULTS AND DISCUSSION Dye Peak (nm) Absorbance (AU) Blue 630 2.00840 Red 498 1.94550 Yellow 427 1.64870 Table 1. Absorption and maximum peaks of each colored dye at room temperature. Dye Observation Time it takes to turn clear (s) Blue Stayed blue for a very long time  before it started turning clear 35 Red Took a little time to start turning  clear 68.45 Yellow Turned clear almost  instantaneously 451.36  Table 2. Observations with the naked eye of the time it takes each dye to turn clear.
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