Question

Which statements about isomers are true? Check all that apply. (6 pt) a) Enantiomers have the same molecular formula. b) Enantiomers are not mirror images of each other that can be superimposed. c) In the ranking of functional groups, alcohols rank above carboxylic acids. d) The R-isomer of a molecule shows an optical rotation of -9°. Its enantiomer shows +9°. e) A molecule with three chiral centers can potentially have nine stereoisomers. f) Meso tartaric acid has the same melting point as its diastere

Answer 1

Answer:

a) TRUE

b) FALSE

c) FALSE

d) TRUE

e) FALSE

f) FALSE

Explanation:

a) Enantiomers have the same molecular formula. TRUE. Because defintion of enantiomer is: One of the two molecules that are mirror images of each other and are non-superposable. To be mirror image must have the same molecular formula.

b) Enantiomers are not mirror images of each other that can be superimposed. FALSE. That is the negation of the enantiomer definition.

c) In the ranking of functional groups, alcohols rank above carboxylic acids. FALSE. In Cahn-Ingold-Prelog rules, carbon of carboxylic acid is bonded with two oxygens but in alcohols is bonded with just one oxygen.

d) The R-isomer of a molecule shows an optical rotation of -9°. Its enantiomer shows +9°. TRUE. One way to differentiate R- S-isomers is with optical rotation. The rotation of R-isomer will be the negative of S-isomer

e) A molecule with three chiral centers can potentially have nine stereoisomers. FALSE. The usual number of isomers is 2ⁿ where n is number of chiral centers. With three chiral centers number is stereoisomers is 8.

f) Meso tartaric acid has the same melting point as its diastere. FALSE. Diastereoisomers have different physical and chemical properties.

I hope it helps!