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2. The optical activity, measured by specific rotation, of pure (R-malic acid is [a]20D-+27% What is the specific rotation of a mixture of 50% and 50% of (R)-malic acid and (S)-malic acid? What is enantiomeric excess of a sample of malic acid containing both enantiomers that has a [al20D -0% [a]20D-27; [a]20D-_ 13.5: [a]20D-+ 13.5°

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