Question 1

Which of the following molecules is chiral?

A. $$\mathrm{CH_3CH_2OH}

B$$. $$\mathrm{CH_3CHBrCH_3}

C$$. $$\mathrm{CH_3CH_2CH_2CH_3}

D$$. $$\mathrm{CH_3CHClBr}$$

Accepted Answer

$$\mathrm{CH_3CHClBr}$$

Question 2

Assign the correct configuration (R or S) to the chiral center in $$\mathrm{CH_3CHBrCl}.$$

Accepted Answer

S

Question 3

Which of the following pairs are enantiomers?

A. $$\mathrm{(R)-2-butanol}$$ and $$\mathrm{(S)-2-butanol}

B$$. $$\mathrm{cis-2-butene}$$ and $$\mathrm{trans-2-butene}

C$$. $$\mathrm{n-butane}$$ and $$\mathrm{isobutane}

D$$. $$\mathrm{meso}-$$tartaric acid and $$\mathrm{(R,R)}-$$tartaric acid

Accepted Answer

A

Question 4

Which of the following best describes a meso compound?

Accepted Answer

A compound with two or more chiral centers and a plane of symmetry

Question 5

Which of the following is the most significant resonance contributor for the acetate ion ($$\mathrm{CH_3COO^-}$$)?

Accepted Answer

The structure with the negative charge delocalized equally over both oxygens

Question 6

Which of the following statements about resonance is TRUE?

Accepted Answer

The resonance hybrid is more stable than any individual resonance structure

Question 7

Which of the following pairs are resonance forms of each other?

A. $$\mathrm{CH_2$=CH-O^-}$$ and $$\mathrm{CH_2$^- -CH=O}

B$$. $$\mathrm{CH_3CH_2OH}$$ and $$\mathrm{CH_3OCH_3}

C$$. $$\mathrm{O=C-O^-}$$ and $$\mathrm{^-O-C=O}

D$$. $$\mathrm{CH_3COOH}$$ and $$\mathrm{CH_3COO^-}$$

Accepted Answer

C

Question 8

Which of the following atoms in acetamide ($$\mathrm{CH_3CONH_2}) $$has a delocalized lone pair?

Accepted Answer

The nitrogen atom

Question 9

Which of the following is the conjugate base of phenol ($$\mathrm{C_6H_5OH}$$)?

Accepted Answer

$$\mathrm{C_6H_5O^-}$$

Question 10

Which of the following acids is the strongest? (Use benchmark pKa values)

A. Acetic acid ($$\mathrm{p}K_a \approx 4.8)

B. $$Phenol ($$\mathrm{p}K_a \approx 10)

C. $$Ethanol ($$\mathrm{p}K_a \approx 16)

D. $$Ammonia ($$\mathrm{p}K_a \approx 38)$$

Accepted Answer

Acetic acid

Question 11

Which of the following solvents would best stabilize the conjugate base of acetic acid in an acid-base reaction?

Accepted Answer

Water

Question 12

Predict the direction of equilibrium for the following acid-base reaction:

$$\mathrm{CH_3COOH} + \mathrm{OH^-} \rightarrow \mathrm{CH_3COO^-} + \mathrm{H_2O}$$

Given $$\mathrm{p}K_a$$ values: acetic acid $$= 4.8$$, water $$= 15.7.$$

Accepted Answer

Equilibrium favors products

Question 13

Which of the following best describes a racemic mixture?

Accepted Answer

A mixture containing equal amounts of both enantiomers

Question 14

Which of the following molecules is optically inactive?

A. $$\mathrm{(R)-2-butanol}

B$$. $$\mathrm{(S)-2-butanol}

C$$. $$\mathrm{meso}-$$tartaric acid

D. $$\mathrm{(R,R)}-$$tartaric acid

Accepted Answer

C

Question 15

Which of the following best explains why the lone pair on the nitrogen in an amide is delocalized?

Accepted Answer

Because the nitrogen lone pair overlaps with the adjacent carbonyl $$\pi$$ system

Question 16

Which of the following is NOT a valid resonance structure for the nitrite ion ($$\mathrm{NO_2$^-}$$)?

Accepted Answer

A structure with a negative charge on the nitrogen atom

Question 17

Which of the following best describes the hybridization of the carbon atom in the formate ion ($$\mathrm{HCOO^-}$$)?

Accepted Answer

sp$$^2$$

Question 18

Which of the following statements about enantiomeric excess (ee) is TRUE?

Accepted Answer

A sample with 100% ee contains only one enantiomer

Question 19

Which of the following is the conjugate acid of ammonia ($$\mathrm{NH_3$}$$)?

Accepted Answer

$$\mathrm{NH_4$^+}$$

Question 20

Which of the following best describes the relationship between cis-2-butene and trans-2-butene?

Accepted Answer

They are diastereomers

Exam 2 Study Guide: Stereochemistry, Resonance, and Acid-Base Chemistry

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