Question

What is the specific rotation of a sample of carvone that is an equal mixture of the R and S enantiomers?

1) -61
2) 64
3) 0
4) 61

Answer 1

The specific rotation for a carvone sample containing equal amounts of R and S enantiomers is 0, due to the cancelation of their opposite optical activities.

Step-by-step explanation:

The specific rotation of a sample of carvone that is an equal mixture of the R and S enantiomers is 0. Enantiomers are mirror images of each other and their specific rotations are equal in magnitude but opposite in sign. This means that if one enantiomer rotates plane-polarized light to the right (dextrorotatory), the other one will rotate it to the left (levorotatory) to the same degree. When present in equal amounts, their rotations cancel each other out, resulting in a net specific rotation of 0 for the mixture.