Post-Lab Questions (As usual, always include explanations in your answers.) 1. D
ID: 545112 • Letter: P
Question
Post-Lab Questions (As usual, always include explanations in your answers.) 1. Do all D-isomers have a positive rotation and L isomers have a negative rotation? 2. Why are we not concemed that the sugars in the oranges would co-distill along with the limonene? It was pointed out that the limonene used in the polarimeter must not contain water. (a) Why should it matter whether water is present in the polarimeter when water is not optically active? (b) i. Would water change the degrees of rotation, a? i. Why or why not? (c) How would the presence of water affect the calculations of the specific rotation? (a) What is the difference between purity and optical purity? (b) Which purity would the refractive index indicate: purity. optical purity, or both? 3. 4.Explanation / Answer
1. Upercase "D" and "L" is the relative configuration to glyceraldehyde and does not stand for dextro (d or +) and levo (l or -). So D and L isomer can have either positive or negative rotation.
Allowed to answer only one question at a time.