Question 1

Which of the following statements regarding optical rotation is not true?

Accepted Answer

A)  All (+)  enantiomers are dextrorotatory.
B)  All R enantiomers are dextrorotatory.
C)  All (-)  enantiomers rotate plane-polarized light in a counterclockwise direction.
D)  All (+)  and (-)  enantiomers rotate plane-polarized light in opposite directions.E) A) and D)
F) A) and B)

Question 2

Which of the following structures has a center of symmetry?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) B) and C)
F) A) and C)

Question 3

The specific rotation of the S-enantiomer of a compound is -120º. What is the enantiomeric excess of a sample of the compound that has a measured specific rotation of -30º.

Accepted Answer

ee = 25% o...

Question 4

What mass of (S)-(-)-mandelic acid is present in a 10 g sample which has an enantiomeric excess of 30% of the S-enantiomer?

Accepted Answer

The answer of What mass of (S)-(-)-mandelic acid is present...

Question 5

The number of chiral centers in progesterone (shown below) is ______.

Accepted Answer

The answer of The number of chiral centers in progesterone...

Question 6

Which of the following structures has a center of symmetry (i.e., center of inversion) ?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) B) and C)
F) A) and C)

Question 7

Complete the following zig-zag structure so that it represents (2R,3S)-2,3-butanediol.

Accepted Answer

The answer of Complete the following zig-zag structure so that...

Question 8

The terms that best describe the relationship between (2R,3S)-2,3-butanediol and (2S,3S)-2,3-butanediol are configurational and diastereomers.

Accepted Answer

A) True 
 B)False

Question 9

Complete the following Fischer diagram so that it represents (2R,3S)-3-bromobutan-2-ol.

Accepted Answer

The answer of Complete the following Fischer diagram so that...

Question 10

How many stereoisomers of 2,3-dimethylbutane, (CH3) 2CHCH(CH3) 2, exist?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) A) and D)
F) A) and B)

Question 11

Complete the following Fischer diagram so that it represents (2R,3R)-butane-2,3-diol.

Accepted Answer

The answer of Complete the following Fischer diagram so that...

Question 12

How many chiral centers are there in the following molecule (the naturally occurring stereoisomer is the male hormone testosterone) ?

Accepted Answer

A)  Three
B)  Four
C)  Six
D)  SevenE) B) and D)
F) A) and D)

Question 13

A solution of 0.1 g/mL of a pure R enantiomer in a 1 dm polarimeter rotates plane polarized light by +4.8 ∘\circ∘ . What is the rotation observed on this solution in a 2 dm polarimeter?

Accepted Answer

A)  +2.4 ∘\circ∘ 
B)  +4.8 ∘\circ∘ 
C)  +9.6 ∘\circ∘ 
D)  +19.2 ∘\circ∘  E) B) and C)
F) A) and D)

Question 14

Complete the following zig-zag structure so that it represents (2S,3R)-2,3-dibromobutane.

Accepted Answer

The answer of Complete the following zig-zag structure so that...

Question 15

Which of the following structures represent the same stereoisomer?

Accepted Answer

A)  only 1 and 2
B)  only 1 and 3
C)  only 2 and 3
D)  1, 2 and 3E) B) and C)
F) C) and D)

Question 16

A pure sample of the R enantiomer of a compound has a specific rotation, [ α\alphaα ], of +20 ∘\circ∘ . A solution containing 0.2 g/mL of a mixture of enantiomers rotates plane polarized light by -2 ∘\circ∘  in a 1 dm polarimeter. What is the enantiomeric excess (%ee)  of the mixture?

Accepted Answer

A)  25% R
B)  40% S
C)  50% S
D)  70% R E) A) and B)
F) None of the above

Question 17

How many stereoisomers of 2,4-pentanediol, CH3CH(OH) CH2CH(OH) CH3, exist?

Accepted Answer

A)  1
B)  2
C)  3
D)  4E) A) and D)
F) All of the above

Question 18

Complete the following Fischer diagram so that it represents (2R,3R)-3-bromobutan-2-ol.

Accepted Answer

The answer of Complete the following Fischer diagram so that...

Question 19

How many isomers (constitutional and stereoisomers)  exist for dimethylcyclobutane?

Accepted Answer

A)  3
B)  4
C)  5
D)  6E) A) and C)
F) B) and C)

Question 20

Complete the following Newman projection so that it represents (2S,3S)-2,3-butanediol.

Accepted Answer

The answer of Complete the following Newman projection so that...

Exam 3: Stereoisomerism and Chirality

Which of the following structures has a center of symmetry?

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A pure sample of the R enantiomer of a compound has a specific rotation, [ α\alphaα ], of +20 ∘\circ∘ . A solution containing 0.2 g/mL of a mixture of enantiomers rotates plane polarized light by -2 ∘\circ∘ in a 1 dm polarimeter. What is the enantiomeric excess (%ee) of the mixture?

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The number of chiral centers in progesterone (shown below) is ______.

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Complete the following Fischer diagram so that it represents (2R,3R)-butane-2,3-diol.

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The terms that best describe the relationship between (2R,3S)-2,3-butanediol and (2S,3S)-2,3-butanediol are configurational and diastereomers.

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Complete the following Fischer diagram so that it represents (2R,3R)-3-bromobutan-2-ol.

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Which of the following structures represent the same stereoisomer?

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What mass of (S)-(-)-mandelic acid is present in a 10 g sample which has an enantiomeric excess of 30% of the S-enantiomer?

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How many stereoisomers of 2,4-pentanediol, CH3CH(OH) CH2CH(OH) CH3, exist?

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Which of the following statements regarding optical rotation is not true?

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The specific rotation of the S-enantiomer of a compound is -120º. What is the enantiomeric excess of a sample of the compound that has a measured specific rotation of -30º.

Correct Answerverifiedee = 25% o...View AnswerShow Answer

Complete the following zig-zag structure so that it represents (2S,3R)-2,3-dibromobutane.

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Complete the following zig-zag structure so that it represents (2R,3S)-2,3-butanediol.

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Complete the following Fischer diagram so that it represents (2R,3S)-3-bromobutan-2-ol.

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Which of the following structures has a center of symmetry (i.e., center of inversion) ?

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Complete the following Newman projection so that it represents (2S,3S)-2,3-butanediol.

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How many stereoisomers of 2,3-dimethylbutane, (CH3) 2CHCH(CH3) 2, exist?

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How many chiral centers are there in the following molecule (the naturally occurring stereoisomer is the male hormone testosterone) ?

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How many isomers (constitutional and stereoisomers) exist for dimethylcyclobutane?

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A solution of 0.1 g/mL of a pure R enantiomer in a 1 dm polarimeter rotates plane polarized light by +4.8 ∘\circ∘ . What is the rotation observed on this solution in a 2 dm polarimeter?

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A pure sample of the R enantiomer of a compound has a specific rotation, [ $\alpha$ ], of +20^$\circ$. A solution containing 0.2 g/mL of a mixture of enantiomers rotates plane polarized light by -2^$\circ$ in a 1 dm polarimeter. What is the enantiomeric excess (%ee) of the mixture?

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How many stereoisomers of 2,4-pentanediol, CH₃CH(OH) CH₂CH(OH) CH₃, exist?

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ee = 25% o...
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How many stereoisomers of 2,3-dimethylbutane, (CH₃) ₂CHCH(CH₃) ₂, exist?

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A solution of 0.1 g/mL of a pure R enantiomer in a 1 dm polarimeter rotates plane polarized light by +4.8^$\circ$. What is the rotation observed on this solution in a 2 dm polarimeter?

Correct Answer
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