Q: Given the free energy diagram below, which reaction would be the fastest? $$\text{Ea} is $$the activation energy, $$\Delta G^\circ is $$the change in Gibbs free energy. A. High $$\text{Ea}$$, large negative $$\Delta G^\circ B. $$Low $$\text{Ea}$$, large negative $$\Delta G^\circ C. $$High $$\text{Ea}$$, small positive $$\Delta G^\circ D. $$Low $$\text{Ea}$$, small positive $$\Delta G^\circ$$

B. Low $$\text{Ea}$$, large negative $$\Delta G^\circ$$

Question 1

Which of the following statements best describes the relationship between thermodynamics and kinetics in a chemical reaction?

Accepted Answer

Thermodynamics describes the favorability of a reaction (using Gibbs Free Energy), while kinetics describes the rate (using activation energy).

Question 2

Given the free energy diagram below, which reaction would be the fastest?

$$	ext{Ea} is $$the activation energy, $$\Delta G^\circ is $$the change in Gibbs free energy.

A. High $$	ext{Ea}$$, large negative $$\Delta G^\circ
B. $$Low $$	ext{Ea}$$, large negative $$\Delta G^\circ
C. $$High $$	ext{Ea}$$, small positive $$\Delta G^\circ
D. $$Low $$	ext{Ea}$$, small positive $$\Delta G^\circ$$

Accepted Answer

B. Low $$	ext{Ea}$$, large negative $$\Delta G^\circ$$

Question 3

Which of the following is true about transition states and intermediates in a multi-step reaction?

Accepted Answer

Intermediates can be isolated, while transition states cannot.

Question 4

Which of the following best describes an acid-base reaction in organic chemistry?

Accepted Answer

Two molecules of opposite charges react to exchange a proton.

Question 5

In the context of reaction mechanisms, which species is most likely to act as a nucleophile?

Accepted Answer

A negatively charged species

Question 6

Which arrow convention is used to show electron movement in organic reaction mechanisms?

Accepted Answer

Arrows move from regions of high electron density to low electron density.

Question 7

Which of the following is a correct statement about the Lewis and Brønsted-Lowry definitions of acids and bases?

Accepted Answer

A Lewis acid is an electron pair acceptor, while a Brønsted-Lowry acid is a proton donor.

Question 8

Which of the following acids is stronger based on their dissociation constants?

Acetic Acid: $$K_a = 1.75 	imes 10$$^{-5}$$
Ammonium: K_a = 5.8$$ 	imes $$10^{-10}$$

Accepted Answer

Acetic acid is stronger because it has a higher $$K_a.$$

Question 9

Which of the following equations correctly relates $$pK_a$$ and $$K_a$$?

Accepted Answer

$$pK_a = -\log_{10}(K_a)$$

Question 10

Rank the following hydrocarbons in order of increasing acidity:

sp$$^3 C$$–H, sp$$^2 C$$–H, sp C–H

Accepted Answer

sp$$^3 C$$–H \u003c sp$$^2 C$$–H \u003c sp C–H

Question 11

Which of the following factors increases the inductive effect and thus the acidity of an alcohol?

Accepted Answer

Increasing the strength, number, and proximity of electronegative atoms

Question 12

Which of the following statements about resonance effects is correct?

Accepted Answer

Resonance effects stabilize the conjugate base, making the acid stronger.

Question 13

Which of the following is the correct product of the reaction between benzoic acid and hydroxide ion ($$	ext{HO}^-$$)?

Accepted Answer

Benzoate ion ($$	ext{C}_6	ext{H}_5	ext{COO}^-) $$and water ($$	ext{H}_2	ext{O})$$

Question 14

Which of the following best describes homolytic cleavage?

Accepted Answer

Each atom receives one electron from the bond, forming radicals.

Question 15

Which of the following molecules would be expected to be more acidic based on element effects?

A. $$	ext{NH}_3  B$$. $$	ext{SH}_2$$

Accepted Answer

$$	ext{SH}_2 is $$more acidic because sulfur is larger and can better stabilize the negative charge.

Question 16

Which of the following is the correct direction of electron movement in a reaction mechanism?

Accepted Answer

From nucleophile to electrophile

Question 17

Which of the following statements about acid-base equilibrium is correct?

Accepted Answer

The reaction favors the formation of the weaker acid and base (higher $$pK_a).$$

Question 18

Which of the following is a correct statement about the effect of alkyl group size on alcohol acidity?

Accepted Answer

The smaller the alkyl group, the more acidic the alcohol.

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