Q: Which of the following best describes the rate law for an $$S_N2$$ reaction?

$$\text{Rate} = k[\text{Nucleophile}][\text{Substrate}]$$

Question 1

In a Brønsted-Lowry acid-base reaction, what is exchanged between the nucleophile and the electrophile?

Accepted Answer

A proton ($$H^+)$$

Question 2

According to the study materials, in Lewis acid-base reactions, what must the electrophile possess to react with a nucleophile?

Accepted Answer

An empty orbital

Question 3

Which of the following best describes a leaving group in a substitution reaction?

Accepted Answer

A molecule that breaks a bond with the electrophile and remains stable after accepting an extra electron pair

Question 4

Which factor is most important in determining the stability of a leaving group after it departs from the substrate?

Accepted Answer

Electronegativity and size of the atom

Question 5

Given the following pairs, which contains the better leaving group for a nucleophilic substitution reaction?

Accepted Answer

$$CH_3-I$ compared to CH_3$-F$$

Question 6

In an $$S_N2$$ reaction, which of the following substrate types is most reactive?

Accepted Answer

Methyl halide

Question 7

Which of the following statements about $$S_N2$$ reactions is correct?

Accepted Answer

The reaction proceeds with inversion of configuration at the carbon center

Question 8

A student is asked to rank the following alkyl halides in order of reactivity toward an $$S_N2$$ reaction: methyl bromide, ethyl bromide, isopropyl bromide, and tert-butyl bromide. Which is the correct order from most to least reactive?

Accepted Answer

Methyl bromide \u003e ethyl bromide \u003e isopropyl bromide \u003e tert-butyl bromide

Question 9

Which of the following best explains why $$S_N1$$ reactions are faster with tertiary alkyl halides than with primary alkyl halides?

Accepted Answer

Tertiary carbocations are more stable due to greater alkyl group electron donation

Question 10

In an $$S_N1$$ reaction, what is the expected stereochemical outcome at the carbon center where substitution occurs?

Accepted Answer

A racemic mixture of enantiomers

Question 11

A chemist is performing a substitution reaction with a strong nucleophile and a primary alkyl halide. Which mechanism is most likely?

Accepted Answer

$$S_N2$$

Question 12

Which of the following is a key difference between $$S_N1$$ and $$S_N2$$ mechanisms?

Accepted Answer

$$S_N1$$ involves a carbocation intermediate, while $$S_N2 is $$concerted

Question 13

Which of the following best describes the rate law for an $$S_N2$$ reaction?

Accepted Answer

$$	ext{Rate} = k[	ext{Nucleophile}][	ext{Substrate}]$$

Question 14

A reaction is performed with a secondary alkyl halide and water as the nucleophile. Which substitution mechanism is most likely and why?

Accepted Answer

$$S_N1$$, because water is a weak nucleophile and secondary carbocations are moderately stable

Question 15

Which of the following statements about leaving groups is correct?

Accepted Answer

Iodide ($$I^-) is a $$better leaving group than fluoride ($$F^-) $$because it is larger and more stable after departure

Question 16

In a real-world pharmaceutical synthesis, why is it important to choose a substrate with a good leaving group for nucleophilic substitution?

Accepted Answer

A good leaving group increases the reaction rate and yield, making the process more efficient and cost-effective

Question 17

Which of the following best explains why $$S_N2$$ reactions are not favored with tertiary alkyl halides?

Accepted Answer

Steric hindrance prevents the nucleophile from attacking the carbon center

Question 18

A student mixes 2-bromopropane with methanol. Which mechanism is most likely, and what is the major product?

Accepted Answer

$$S_N1$$; 2-methoxypropane

Question 19

Which of the following is true regarding the effect of nucleophile strength on substitution mechanisms?

Accepted Answer

Strong nucleophiles favor $$S_N2$$ mechanisms, while weak nucleophiles favor $$S_N1$$ mechanisms

Nucleophilic Substitution and Acid-Base Reactions in General Chemistry

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