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posted by  madz on 11/19/2008 1:34:05 PM  |  status: Live  

optical rotation

Course Textbook Chapter Problem
Organic Chemistry N/A steriochemistry N/A
Question Details:
A student measured the optical rotation of his sample at two different concentrations. At
0.10 g/mL, she measured [a]D at +12°. At 0.05 g/mL, she measured [a]D = +186°. How
can this be?

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posted by Nicholas(MND) on 11/29/2008 11:57:10 PM  |  status: Live
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madz's comment:
"thanks a lot !!!"
Response Details:
since optical rotatio depends on the concentration of the sample it should become half of the observed rotation when the sample concentration is decreased by half, so the first observed rotation is wrong. since rotations of +120 and + 3720 cannot be differentiated it would have wrongly taken as +120 so at 0.10g/ml the rotation is +3720 so on decreasing the conc. by half the rotatio will be decreased by half to give rotatio of +1860
 
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