Question 1

Which of the following statements best describes a chiral center in an organic molecule?

Accepted Answer

A carbon atom bonded to four different groups.

Question 2

A sample of a chiral compound has a measured specific rotation of $$+25^	ext{o}. If $$the literature value for the pure enantiomer is $$+50^	ext{o}$$, what is the enantiomeric excess (ee) of the sample?

Accepted Answer

$$50\%$$

Question 3

Which of the following pairs are diastereomers?

Accepted Answer

Two stereoisomers that are not mirror images of each other.

Question 4

A mixture contains equal amounts of $$(R)-2-$$butanol and $$(S)-2-$$butanol. Which term best describes this mixture?

Accepted Answer

Racemic mixture

Question 5

Using the Cahn-Ingold-Prelog rules, which group has the highest priority when attached to a chiral center?

Accepted Answer

The group with the atom of highest atomic number directly attached to the chiral center.

Question 6

Which of the following structures is meso-tartaric acid an example of?

Accepted Answer

A compound with chiral centers but is overall achiral due to an internal plane of symmetry.

Question 7

Which of the following best describes a prochiral carbon?

Accepted Answer

A carbon atom that can become chiral by changing one of its attached groups.

Question 8

Assign the correct configuration to a chiral center with the following priorities: $$1 = 	ext{Br}$$, $$2 = 	ext{OH}$$, $$3 = 	ext{CH}_3$$, $$4 = 	ext{H} ($$with H in the back). If the sequence from 1 to 2 to 3 is clockwise, what is the configuration?

Accepted Answer

$$(R)$$

Question 9

Which of the following is a correct example of a substitution reaction?

Accepted Answer

$$\ce{CH3Br + OH^- -\u003e CH3OH + Br^-}$$

Question 10

In a radical halogenation reaction, which step is responsible for the chain reaction to continue?

Accepted Answer

Propagation

Question 11

Which of the following best describes a transition state in a reaction coordinate diagram?

Accepted Answer

A high-energy, unstable arrangement of atoms at the maximum energy point along the reaction path.

Question 12

Which of the following statements about Le Chatelier's Principle is correct?

Accepted Answer

If a system at equilibrium is disturbed, the system will shift to counteract the disturbance and restore equilibrium.

Question 13

Which of the following is an example of a homolytic bond dissociation?

Accepted Answer

$$\ce{Cl2 -\u003e 2Cl\cdot}$$

Question 14

Which of the following best describes an exergonic reaction?

Accepted Answer

A reaction with $$\Delta G \u003c 0$$ that releases free energy.

Question 15

Which of the following is NOT a possible intermediate in a reaction mechanism?

Accepted Answer

Transition state

Question 16

A reaction has an activation energy of $$50\ \mathrm{kJ/mol}$$ and a $$\Delta H of$$ $$-20\ \mathrm{kJ/mol}. $$Which of the following statements is true?

Accepted Answer

The reaction is exothermic and requires an input of energy to proceed.

Question 17

Which of the following best describes the difference between initiation and propagation in a radical reaction?

Accepted Answer

Initiation generates radicals, while propagation uses radicals to form products and new radicals.

Question 18

Which of the following is a correct example of an elimination reaction?

Accepted Answer

$$\ce{CH3CH2Br + KOH -\u003e CH2=CH2 + KBr + H2O}$$

Question 19

Which of the following best describes a reaction intermediate?

Accepted Answer

A species that is formed and consumed during the reaction but does not appear in the overall equation.

Question 20

In a reaction coordinate diagram, what does the highest point along the path represent?

Accepted Answer

The transition state

Question 21

Which of the following is a correct example of a rearrangement reaction?

Accepted Answer

$$\ce{CH3CH2CH2Br -\u003e[heat] CH3CHBrCH3}$$

Chirality, Stereochemistry, and Reaction Mechanisms in General Chemistry

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