Question 1

The specific rotation of a pure substance is -5.90°.What is the percentage of this isomer in a mixture with an observed specific rotation of -2.95°?

Accepted Answer

A) 25% 
B) 50% 
C) 75% 
D) 80% 
E) 0%

Question 2

Provide a perspective drawing of (2R,3S)-1,2,3-trichloropentane.

Accepted Answer

The answer of Provide a perspective drawing of (2R,3S)-1,2,3-trichloropentane....

Question 3

Identify the compound(s)with asymmetric centers.

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 4

The compound below contains an asymmetric center at nitrogen.Why can't individual stereoisomers of this compound be isolated at room temperature?

Accepted Answer

The answer of The compound below contains an asymmetric center...

Question 5

Label each asymmetric center in the compound below as R or S.

Accepted Answer

The answer of Label each asymmetric center in the compound...

Question 6

Which of the following compounds has an S configuration?

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 7

Structure of cholesterol is shown below.How many stereoisomers exist for this molecule?

Accepted Answer

A) 8 
B) 32 
C) 64 
D) 128 
E) 256

Question 8

A sample of (+)and (-)-3-chlorohexane has a rotation of -20 degrees.Pure (+)-3-chlorohexane has a rotation of +40 degrees.Calculate the enantiomeric excess and the amount of (-)and (+)-3-chlorohexane in the original sample.

Accepted Answer

The answer of A sample of (+)and (-)-3-chlorohexane has a...

Question 9

Which of the following is chiral?

Accepted Answer

A) cis-1-bromo-3-chlorocyclobutane 
B) trans-1-bromo-3-chlorocyclobutane 
C) cis-1,4-dimethylcyclohexane 
D) cis-1,3-dimethylcyclohexane 
E) trans-1,3-dimethylcyclohexane

Question 10

In the Fischer projection below,what are the configurations of the two asymmetric centers?

Accepted Answer

A) 2R,3R 
B) 2R,3S 
C) 2S,3R 
D) 2S,3S 
E) cannot be determined from structure

Question 11

Which of the following statements correctly pertains to a pair of enantiomers?

Accepted Answer

A) They rotate the plane of polarized light by exactly the same amount and in opposite directions. 
B) They rotate the plane of polarized light by differing amounts and in opposite directions. 
C) They rotate the plane of polarized light by differing amounts and in the same direction. 
D) They have different melting points. 
E) They have the same melting point,but they have different boiling points.

Question 12

Draw any diastereomer of (2R,3R)-2,3-dichloropentane.Be careful to indicate proper stereochemistry.

Accepted Answer

The answer of Draw any diastereomer of (2R,3R)-2,3-dichloropentane.Be careful to...

Question 13

Is the molecule shown below chiral or achiral?

Accepted Answer

The answer of Is the molecule shown below chiral or...

Question 14

Is the molecule shown below chiral or achiral?

Accepted Answer

The answer of Is the molecule shown below chiral or...

Question 15

Provide a careful structure for (2S,3S)-2,3-dibromohexane.

Accepted Answer

The answer of Provide a careful structure for (2S,3S)-2,3-dibromohexane....

Question 16

Which of the following is a true statement?

Accepted Answer

A) All chiral molecules possess a plane of symmetry. 
B) All achiral molecules are meso. 
C) All molecules which possess a single chirality center of the S configuration are levorotatory. 
D) A mixture of achiral compounds will be optically inactive. 
E) All molecules which possess two or more chirality centers will be chiral.

Question 17

Which of the following terms best describes the pair of compounds shown: enantiomers,diastereomers,or the same compound?

Accepted Answer

The answer of Which of the following terms best describes...

Question 18

Provide a perspective drawing of the enantiomer of (2R,3S)-1,2,3-trichloropentane.

Accepted Answer

The answer of Provide a perspective drawing of the enantiomer...

Question 19

What is the relationship between the structures shown below?

Accepted Answer

A) enantiomers 
B) diastereomers 
C) configurational isomers 
D) identical compounds 
E) constitutional isomers

Question 20

Which of the following terms best describes the pair of compounds shown: enantiomers,diastereomers,or the same compound?

Accepted Answer

The answer of Which of the following terms best describes...

Exam 4: Isomers: the Arrangement of Atoms in Space

The specific rotation of a pure substance is -5.90°.What is the percentage of this isomer in a mixture with an observed specific rotation of -2.95°?

Provide a perspective drawing of (2R,3S)-1,2,3-trichloropentane.

Identify the compound(s) with asymmetric centers.

The compound below contains an asymmetric center at nitrogen.Why can't individual stereoisomers of this compound be isolated at room temperature?

Label each asymmetric center in the compound below as R or S.

Which of the following compounds has an S configuration?

Structure of cholesterol is shown below.How many stereoisomers exist for this molecule?

A sample of (+)and (-)-3-chlorohexane has a rotation of -20 degrees.Pure (+)-3-chlorohexane has a rotation of +40 degrees.Calculate the enantiomeric excess and the amount of (-)and (+)-3-chlorohexane in the original sample.

Which of the following is chiral?

In the Fischer projection below,what are the configurations of the two asymmetric centers?

Which of the following statements correctly pertains to a pair of enantiomers?

Draw any diastereomer of (2R,3R)-2,3-dichloropentane.Be careful to indicate proper stereochemistry.

Is the molecule shown below chiral or achiral?

Is the molecule shown below chiral or achiral?

Provide a careful structure for (2S,3S)-2,3-dibromohexane.

Which of the following is a true statement?

Which of the following terms best describes the pair of compounds shown: enantiomers,diastereomers,or the same compound?

Provide a perspective drawing of the enantiomer of (2R,3S)-1,2,3-trichloropentane.

What is the relationship between the structures shown below?

Which of the following terms best describes the pair of compounds shown: enantiomers,diastereomers,or the same compound?