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April 18, 2026, 07:43:09 am
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Author Topic: UV-visible multchoice help :O  (Read 1288 times)  Share 

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PB

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UV-visible multchoice help :O
« on: May 15, 2013, 06:23:33 pm »
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Which of the following tasks could be completed using UV-visible spectrometry? (A and B are defs wrong)
C) detecting the presence of a performance enhancing drug in a urine sample?
D) determining the concentration of a sodium chloride solution

The answer says C, but can't UV vis also accomplish D via calibration curves?
Thanks.
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jgoudie

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Re: UV-visible multchoice help :O
« Reply #1 on: May 15, 2013, 07:23:05 pm »
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No, Sodium Chloride will not absorb in the UV-Vis, this is best done via AAS due to the presence of a metal ion.



Quote from: PB on May 15, 2013, 06:23:33 pm
Which of the following tasks could be completed using UV-visible spectrometry? (A and B are defs wrong)
C) detecting the presence of a performance enhancing drug in a urine sample?
D) determining the concentration of a sodium chloride solution

The answer says C, but can't UV vis also accomplish D via calibration curves?
Thanks.
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PB

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Re: UV-visible multchoice help :O
« Reply #2 on: May 15, 2013, 10:07:29 pm »
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Hey jgoudie,
Thanks so much for answering. but could you please explain to me why sodium chloride would not be able to be detected by a UV-Visible spectrophotometer? Is it because only atoms' valence electrons can be excited by UV-VIS radiation whereas, sodium chloride is disasocciated as ions in solution?
Thanks
PB
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Fluttershy

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Re: UV-visible multchoice help :O
« Reply #3 on: May 15, 2013, 11:32:52 pm »
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Forgive me, I haven't done this stuff for a while, but sodium chloride wouldn't be detected by UV-Vis because it dissolves into a colourless solution, right? Therefore the absorbance reading should be really low, if present at all. (I think.) I know this probably isn't the best reasoning...
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PB

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Re: UV-visible multchoice help :O
« Reply #4 on: May 16, 2013, 01:54:21 pm »
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You might be right..but I think that the spectrometer also shoots UV radiation at the solution, it doesn't only shine radiation of the visible spetra. So i think the solution being colourless wouldn't matter much
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PB

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Re: UV-visible multchoice help :O
« Reply #5 on: May 17, 2013, 11:34:26 pm »
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Bump :S
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saba.ay

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Re: UV-visible multchoice help :O
« Reply #6 on: May 18, 2013, 01:51:50 pm »
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Quote from: PB on May 16, 2013, 01:54:21 pm
You might be right..but I think that the spectrometer also shoots UV radiation at the solution, it doesn't only shine radiation of the visible spetra. So i think the solution being colourless wouldn't matter much

That's right, but that works only if the compound being analyzed absorbs UV radiation. From what I understand, sodium chloride doesn't absorb UV light either. Generally, it is colourless organic compounds which absorb UV light.

If I was doing this question, I'd probably have just picked C, seeing as a urine sample would produce a coloured solution. :P
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PB

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Re: UV-visible multchoice help :O
« Reply #7 on: May 20, 2013, 09:11:37 pm »
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Fair enough, sounds reasonable to me.
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