Q: Which of the following is a correct formula for calculating enantiomeric excess (ee)?

$$ee = [\%\text{ of one enantiomer}] - [\%\text{ of the other enantiomer}]$$

Q: A sample of MSG (monosodium glutamate) has a specific rotation $$[\alpha] = +10. If $$the enantiopure $$[\alpha] = +24$$, what is the enantiomeric excess (ee)?

$$ee = (10/24) \times 100\% = 42\%$$

Question 1

Which of the following statements best describes a chiral molecule?

Accepted Answer

A molecule that is non-superimposable upon its mirror image.

Question 2

Which of the following is true about enantiomers?

Accepted Answer

They are non-superimposable mirror images.

Question 3

A molecule with two stereocenters can have a maximum of how many stereoisomers?

Accepted Answer

$$4$$

Question 4

Which of the following is NOT a requirement for a carbon atom to be a stereocenter?

Accepted Answer

It must be part of a ring structure.

Question 5

Which of the following best describes a racemic mixture?

Accepted Answer

A sample containing equal amounts of both enantiomers.

Question 6

A solution contains 80% of enantiomer A and 20% of enantiomer B. What is the enantiomeric excess (ee)?

Accepted Answer

$$60\%$$

Question 7

Which property is identical for a pair of enantiomers?

Accepted Answer

Melting point

Question 8

Which of the following is true about diastereomers?

Accepted Answer

They are stereoisomers that are not mirror images.

Question 9

Which of the following statements about the Cahn-Ingold-Prelog (CIP) system is correct?

Accepted Answer

Priority is assigned based on atomic number; higher atomic number gets higher priority.

Question 10

A chiral compound rotates plane-polarized light clockwise. What is the correct term for this property?

Accepted Answer

Dextrorotatory

Question 11

Which of the following is a correct formula for calculating enantiomeric excess (ee)?

Accepted Answer

$$ee = [\%	ext{ of one enantiomer}] - [\%	ext{ of the other enantiomer}]$$

Question 12

Which of the following molecules is achiral?

Accepted Answer

A molecule with an internal mirror plane.

Question 13

Which of the following is true regarding the physical properties of diastereomers?

Accepted Answer

They have different physical properties and can be separated by physical means.

Question 14

Which of the following is NOT a type of stereoisomer?

Accepted Answer

Constitutional isomer

Question 15

A sample of MSG (monosodium glutamate) has a specific rotation $$[\alpha] = +10. If $$the enantiopure $$[\alpha] = +24$$, what is the enantiomeric excess (ee)?

Accepted Answer

$$ee = (10/24) 	imes 100\% = 42\%$$

Question 16

Which of the following is a correct statement about the relationship between (R)/(S) configuration and optical rotation (+/-)?

Accepted Answer

There is no direct relationship between (R)/(S) configuration and the sign of optical rotation.

Question 17

Which of the following is true about the separation of enantiomers and diastereomers?

Accepted Answer

Diastereomers are more easily separated than enantiomers due to their different physical properties.

Question 18

Which of the following is true about the (E)/(Z) nomenclature for alkenes?

Accepted Answer

It is based on the Cahn-Ingold-Prelog priority rules.

Question 19

Which of the following real-world examples illustrates the importance of stereochemistry in pharmaceuticals?

Accepted Answer

Ibuprofen is sold as a racemic mixture, but only one enantiomer is bioactive.

Stereochemistry: Isomers, Chirality, Enantiomers, and Diastereomers

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