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How are we monitoring the loss of dye?
How are we monitoring the loss of dye?
As you observed in the previous videos, an indication of the progression of the oxidation reaction of dyes is the loss of color - this is because the products are colorless. We can make use of this when choosing a method to monitor the concentration of our dye! Since the only component of the reaction mixture that absorbs visible light is the dye, and according to Beer's Law absorbance is proportional to concentration, we can use absorption spectroscopy to monitor the loss of reactant.
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Determining the order with respect to dye
Determining the order with respect to dye
Materials: 3.40 x 10-5 M Yellow 6, 0.090 M bleach solution, 0.180 M bleach solution, 10 mL pipet, 1 mL syringe, stirrer, spectrophotometer
Materials: 3.40 x 10-5 M Yellow 6, 0.090 M bleach solution, 0.180 M bleach solution, 10 mL pipet, 1 mL syringe, stirrer, spectrophotometer
Go here to access the simulation (it might take a minute for it to load fully).
Use the pipet to dispense between 9.00 mL and 9.90 mL of dye into the vial.
Place the vial into the spectrometer and add the stirrer.
Use the 1 mL syringe to add the needed amount of either bleach solution to the vial in order to reach a total reaction mixture volume of 10.00 mL.
Cover the vial with the black lid to start the measurement.
Once the measurement is complete, inspect the three plots generated (absorbance vs. time, ln(absorbance) vs. time, 1/absorbance vs. time) and choose the one that is most useful in determining the order of the reaction (go back to the Background theory section if you need to remind yourself of what the plots for different reaction orders look like). Input your name, lab section (under lab ID), and an informative graph title (including the quantities and bleach concentrations tested) and save (print) the plot.
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