Question

Which of the following defines optical purity?

• A. Ratio of observed rotation to the rotation of pure enantiomer
• B. Ratio of rotation of pure enantiomer to the observed rotation
• C. Product of rotation of pure enantiomer and observed rotation
• D. None of the above

Answer 1

The correct option is A Ratio of observed rotation to the rotation of pure enantiomer

For a mixture that is not a racemic mixture, the optical purity of the mixture is specified.
It is defined as the ratio of observed rotation to the rotation of pure enantiomer.
$\%\text{Optical purity}=\frac{\text{Observed optical rotation}}{\text{Optical rotation of pure enantiomer}}\times 100\%$