A racemate contains the same amount of substance of each member of an enantiomer pair. Their equal and opposite contributions cancel in ordinary solution polarimetry under identical conditions. Zero net optical rotation therefore does not establish achirality of the individual molecules.[ref]
5.8 Racemic Mixtures and the Resolution of Enantiomers. McMurry, Organic Chemistry, §5.8: equal enantiomer populations and cancelling optical rotations
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