Calculating the Optical Rotation Value

In summary, the problem involves a compound with a (+) enantiomer and a (-) enantiomer, with a 50* optical rotation. A pure sample contains 42% (+) enantiomer and 58% (-) enantiomer. The question asks for the optical rotation value, which can be calculated by taking 58% and subtracting 42% to find the contribution of the (-) enantiomer. This results in a negative value of -16, indicating that 16% of the (-) enantiomer is optically active. This corresponds to an optical rotation of -8*, which makes sense given the small percentage and negative value.
  • #1
Interception
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Homework Statement

So the problem states that we have a (+) enantiomer of a coumpund with an optical rotation of 50*. If a pure sample containes 42% of the (+) enantiomer and 58% of the (-) enantioimer, what is the optical rotation value. (By * i mean degrees)



Homework Equations

I'm not sure which equation would apply to this situation. It's a small school, and our proffesor hardly went over this subject. We'd done a few problems, but none where like this.



The Attempt at a Solution

I know that it will be a negative value since the the (-) enantiomer outnumbers the (+). I didn't know how to approach the problem, so I took 58%-the 42% to see how much of the (-) will contribute to the rotations since the 42% of the (+) enantiomer will counteract 42% of the (-) enantiomer. I got -16. I took this mean that 16% of the (-) enantiomer would be optically active, and 16% of 50 is 8, or in this case -8* of optical rotation. The negative value makes sense, and the fact that it's not a large number. Does this look right?
 
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  • #2
Looks OK to me.
 

What is optical rotation?

Optical rotation is a measure of the rotation of the plane of polarized light as it passes through a substance.

What is the purpose of calculating the optical rotation value?

The purpose of calculating the optical rotation value is to determine the concentration and purity of a substance, as well as to identify and characterize unknown compounds.

How is the optical rotation value calculated?

The optical rotation value is calculated by measuring the angle of rotation of polarized light through a sample, using a polarimeter. This value is then compared to a standard substance with a known optical rotation value.

What factors can affect the optical rotation value?

The optical rotation value can be affected by the concentration, temperature, and wavelength of the light passing through the sample, as well as the length of the sample tube and the specific rotation of the substance being tested.

What are some common applications of optical rotation measurement?

Optical rotation measurement is commonly used in the pharmaceutical industry to assess the purity and concentration of drugs. It is also used in the food and beverage industry to determine the authenticity and quality of products, such as honey and wine. Additionally, it is used in chemical and biochemical research to identify and characterize new compounds.

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