A racemic mixture is a mixture that contains equal amounts of two enantiomers of a chiral molecule.
Key points:
- Composition: 50% of the (R)-enantiomer and 50% of the (S)-enantiomer.
- Optical activity: Optically inactive because the rotations of the two enantiomers cancel each other out.
- Example: Racemic lactic acid has equal (R)-lactic acid and (S)-lactic acid.
Simple way to remember:
- Enantiomers rotate light in opposite directions → mix them 50:50 → light rotation cancels → racemic mixture.