Evaluating Proposals Presented below are four preliminary student proposals (num

Question

Evaluating Proposals Presented below are four preliminary student proposals (numbered 1 through 4) to quantitatively characterize and finely control the light emitted from glow stick chemistry with the objective of identifying one or more trends. Proposal 1 Activate a green glow stick. Open and transfer activated solution into a 1 dram (3.7 mLI vial. Add5 mL of 0.1 M sodium salicylate in ethanol at room temperature (200C by transfer pipette. Mix well. Now measure the intensity by emission spectrometer, Next, change the temperature to 400C. Measure the intensity. Continue in 200C increments until 1000C Plot intensity vs. temperature (in C). Look for trends. Proposal 2 Activate a green glow stick. Label two 1dram (3.7 mL) vials "A" and "B." Open glow stick and transfer 3.00 mLofactivated solution into vial "A" and another 3.00 mL into vial "B" over a spill containment bin. Cap both and record the emission spectrum vi emission spectrometer of both to confirm equivalent output, establish a baseline and determine Amax. To vial "A" introduce every 30 seconds 20 uL of 0.1M KOH by 20-200 uL micropipette set at 20 ul lmmediately recap and mix by four gentle inversions, then record the emission spectrum. Repeat cycle for a total of 10 minutes. At 10 minutes record the emission spectrum for vial "B Pipette 20 WL of 0.1 M KOH into vial "B", mix and immediately record the emission spectrum. Use the results from vial "B" to confirm that the activated solution light output remains reasonably constant over 10 minutes (or if it deviates, by how much) and when challenged at 10 minutes with 20 uL of 0.1 M KOH the system at 10 minutes responds as it did at 30 seconds with vial "A" (and if it doesn't, by how much). Plot the intensity at the Ama versus volume of 0.1 M KOH. Analyze for trends. Proposal 3 Use three red glow sticks. Combine activated red glow stick solution into vial, Distribute 3 mL of this activated red solution into separate 2 dram (7.4 mLI vials. Treat vials according to the following schedule: Vial Acid (0.01 M HCl in ethanol) Temperature (by ice bath or hot water bath) 1 drop 5 drops 10 drops 15

Explanation / Answer

Solution:

1. The quantitative proposals are 2 and 4 as they are experimentally done for finding the strength of glow stick green and red coloured quantitatively by using spectrometer an highly precise experimental technique for finding the wavelength by using emission spectrum.

2. Proposal 1 and 3 are done qualitatively by changing parameters in periodic for observing the threshold of the glowing stick as in proposal 1 initially concentration of solution used followed in temperature change to 40 C and in 3 heating and cooling are used which helps in finding the durability and effectiveness of glow stick at various condition.

3. Proposal 2 and 3 falls under positive control as the parameter change is done in gradual way which gives the response to disturbance with robust result a must for glow stick market.

4. Proposal 1 and 4 is referred to negative control as the parameters are shifted in linear phase where a desired result in real-time application cannot be observed, these two tests helps in checking the functionality of glowstick but wont help in durability test.

5. Proposal 1,2 and 3 had independent variables with finite increments helps in analysis of trends for glow stick behaviour which helps in discovery of predictive power.

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