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Topic: Beer-Lambert Spectroscopy  (Read 1981 times)

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Offline Firehchicken

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Beer-Lambert Spectroscopy
« on: January 18, 2018, 10:48:39 PM »
So recently I had a practical session where I would learn about the Beer-Lambert law and spectroscopy (absorbance, concentration of solution etc.)

During the experiment, we were to test the absorbances of  3 different concentrations of dye solutions over 400nm to 800nm wavelengths (visible spectrum).

In my following report, I had to explain why the absorbance of the lowest concentration dye was measured first, then proceed to the higher concentrations.

I can't seem to figure out why ??? ??? ???

Offline mjc123

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Re: Beer-Lambert Spectroscopy
« Reply #1 on: January 19, 2018, 04:42:03 AM »
Well, what might happen if you started with the most concentrated, then moved on to the less concentrated? Think about your experimental procedure. Did you use the same cuvette for all measurements?

Offline Corribus

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Re: Beer-Lambert Spectroscopy
« Reply #2 on: January 19, 2018, 10:20:46 AM »
This is, by the way, standard operating procedure for any analytical measurement in which a concentration calibration curve is generated. This isn't something particular to UV-Vis spectroscopy. So maybe that provides a hint to help you figure out the answer.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Firehchicken

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Re: Beer-Lambert Spectroscopy
« Reply #3 on: January 22, 2018, 07:17:07 AM »
Well, what might happen if you started with the most concentrated, then moved on to the less concentrated? Think about your experimental procedure. Did you use the same cuvette for all measurements?

Nope, we used 3 different concentrations of 3 different dyes, so a total of 9 cuvettes were used.

Still can't figure it out lol... my professor said something along the lines of the machine generating weird curves if we went in the reverse order. Idk tho cuz even he wasn't sure why....

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