Lab 9 Notes - LABS Even though I was trying very hard to...

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LABS Even though I was trying very hard to get around it because it destroys the point of absorption spectrums, stick with the approximation made on Friday. Now, in your lab reports, I hope you can write about how you would improve the lab so we don't have to make this approximation. What kind of data (think about the extinction coefficients) would you need to do the "correct" calculations? What could be wrong with just looking at the lamda max's all the time? I expect all of you to address my question in your lab reports. If I don't see it, I will just take off points because you will be missing the point. I don't care what any other Chem 1A student says about the lab report. It makes no difference to me if other Chem 1A students don't address this point in their lab reports. It's important for you to know this because it's an important concept for the midterm and final. If you need help with the lab report: Office Hours. Both Cherry and Grape Kool Aid only contain Red 40 and Blue 1 dyes. The two just differ in their relative concentrations. I'm sure you know which dye applies and doesn't apply to a specific Kool Aid sample. With that said, you shouldn't need to solve simultaneous equations (2 equations with 2 unknowns). Calculations are easy now! S I don't expect you guys to give me Absorption spectrums (Abs vs. wavelength plots). Don't worry about it. In your report, I would still like you to address my questions from my last email because I think it's good for your chemistry soul. This also means error analysis . OUTSIDE SOURCES Collecting Absorbance Data from the Spectrophometer 8. Make sure the right light (indicates the light source is on) is lit on the spectrophotometer. 9. Adjust the wavelength knob until the wavelength is 630 nm. 10. With no sample in the holder, the transmittance should be at 0%. Turn the bottom left knob until the transmittance is 0%. 11. Now place the blank sample (cuvette filled with distilled water) into the spectrophotometer. The transmittance should now be 100%. Turn the bottom right knob until the transmittance is 100%. 12. Taking the cuvette with the 4.0M solution, use a Kimwipe to clean the sides of the cuvette. 13. Place this sample into the spectrophotometer, close the sample door and record the absorbance value. 14.
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This note was uploaded on 09/22/2010 for the course CHEM 3 taught by Professor Pedersen during the Fall '08 term at University of California, Berkeley.

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Lab 9 Notes - LABS Even though I was trying very hard to...

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