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Topic: how to find the ratio of enatiomers in a mixture  (Read 2258 times)

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Offline sarkar

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how to find the ratio of enatiomers in a mixture
« on: September 03, 2014, 02:50:32 PM »
A dextrorotatory isomer has a specific rotation of +51.3 ° at30°C . A sample containing both isomers has specific rotation value +30.8° at 20°C.
What is the percentage of the two enantiomers in the sample?

Offline rwiew

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Re: how to find the ratio of enatiomers in a mixture
« Reply #1 on: September 03, 2014, 11:57:35 PM »
We'll need to see some attempts from you. What's the formula for enantiomeric excess, specific rotation of a mixture?

Offline Enthalpy

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Re: how to find the ratio of enatiomers in a mixture
« Reply #2 on: September 04, 2014, 03:54:03 PM »
Intuitively, this should need the concentrations in both samples. If not, the second sample could be just more dilute.

Offline rwiew

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Re: how to find the ratio of enatiomers in a mixture
« Reply #3 on: September 04, 2014, 10:08:30 PM »
Intuitively, this should need the concentrations in both samples. If not, the second sample could be just more dilute.

Nope, they are specific rotations = per unit concentration.

Offline Enthalpy

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Re: how to find the ratio of enatiomers in a mixture
« Reply #4 on: September 05, 2014, 11:55:38 AM »
Thanks!

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