August 08, 2022, 03:13:47 AM
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Topic: Spectrophotometry question  (Read 597 times)

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Offline happyfunny

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Spectrophotometry question
« on: April 23, 2022, 01:47:11 PM »
How do I answer this question?

Using spectrophotometry, the researcher determines the initial rate of the
enzyme reaction as a change in absorbance of 0.2/min, using 10 ┬Ál of ADH (5
mg/ml). Convert this rate to the amount of product formed per minute
considering the molar extinction coefficient of NADH at the wavelength used is
6.22 x 103 M-1cm-1

Offline Corribus

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Re: Spectrophotometry question
« Reply #1 on: April 23, 2022, 03:08:57 PM »
At Chemical Forums you have to provide your work before you may receive help. If you are stuck, consider what pieces of information you are given and how they relate to what you're supposed to find. Sometimes dimensional analysis (units) can help.

What do you know about the relationship between the molar extinction coefficient, absorbance, and concentration? A reaction rate is just an amount of substance per units time.
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 happyfunny

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Re: Spectrophotometry question
« Reply #2 on: April 23, 2022, 04:58:38 PM »
At Chemical Forums you have to provide your work before you may receive help. If you are stuck, consider what pieces of information you are given and how they relate to what you're supposed to find. Sometimes dimensional analysis (units) can help.

What do you know about the relationship between the molar extinction coefficient, absorbance, and concentration? A reaction rate is just an amount of substance per units time.

I know I need to use the beer lambert law. So A=ecl. e is the molar extinction coefficient, which in this case is 6.22 x 103 M-1cm-1. l is 1 cm. I think A is .2. So I am confused, am I supposed to calculate .2/(6.22 x 103 M-1cm-1)?

Offline Babcock_Hall

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Re: Spectrophotometry question
« Reply #3 on: April 25, 2022, 08:58:59 AM »
You are forgetting about the units of time in the denominator.  It might help a little to write the balanced equation for the reaction catalyzed by alcohol dehydrogenase.

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