Final answer:
The (R,R)- and (S,S)-labetalol enantiomers would rotate plane-polarized light in opposite directions because enantiomers rotate light equally but in inverted directions: (R,R)- is dextrorotatory and (S,S)- is levorotatory.
Step-by-step explanation:
Would (R,R)- and (S,S)-labetalol be expected to rotate plane-polarized light in the same direction? To answer this question, we need to understand that enantiomers - non-superimposable mirror images of a compound - rotate plane-polarized light by equal amounts but in opposite directions. In the case of (R,R)-labetalol and (S,S)-labetalol, since they are enantiomers, they would be expected to rotate light in opposite directions. Option 1) (R,R)-labetalol would rotate plane-polarized light to the right (dextrorotatory), while (S,S)-labetalol would rotate it to the left (levorotatory).
The observed rotation of plane-polarized light depends on the molecular configuration of chiral centers in a substance. An R or S designation refers to the configuration of atoms around a chiral center and does not always correlate with the direction (dextrorotatory or levorotatory) in which that enantiomer will rotate the plane of polarized light. It is important to note that an enantiomer's designation as R or S is separate from its optical activity (d or l), which must be determined experimentally