Question 1

Which of the following best describes a Brønsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($\mathrm{H^+}$) to another species

Question 2

Given the following reaction: $\mathrm{CH_3COOH + NH_3 \rightarrow CH_3COO^- + NH_4^+}$, which species is the conjugate base?

Accepted Answer

$\mathrm{CH_3COO^-}$

Question 3

Which of the following statements about resonance structures in acid-base reactions is correct?

Accepted Answer

Resonance structures with complete octets and minimal charge separation contribute most to the overall structure.

Question 4

In the reaction $\mathrm{H_2O + NH_3 \rightarrow OH^- + NH_4^+}$, which species acts as the Brønsted-Lowry base?

Accepted Answer

$\mathrm{NH_3}$

Question 5

Which of the following is the correct equilibrium expression for the dissociation of acetic acid in water?

Accepted Answer

$K_a = \dfrac{[H_3O^+][A^-]}{[HA]}$

Question 6

If the $pK_a$ of acetic acid is 4.76 and the $pK_a$ of carbonic acid is 6.36, which acid is stronger?

Accepted Answer

Acetic acid

Question 7

Which of the following best explains why $\mathrm{CH_3COOH}$ is a stronger acid than $\mathrm{CH_3CH_2OH}$?

Accepted Answer

The carboxylate ion ($\mathrm{CH_3COO^-}$) is stabilized by resonance delocalization.

Question 8

What is the relationship between $pK_a$ and acid strength?

Accepted Answer

A smaller $pK_a$ means a stronger acid.

Question 9

Which of the following is the correct formula to calculate $\Delta G^\circ$ for an acid-base reaction at 298K?

Accepted Answer

$\Delta G^\circ = -RT \ln K_{eq}$

Question 10

In the acid-base reaction between 2-butene and $\mathrm{HBr}$, what is the role of the $\pi$ electrons?

Accepted Answer

They act as a Brønsted-Lowry base by donating electron density to the proton.

Question 11

Which of the following is true regarding the use of curved arrows in acid-base reaction mechanisms?

Accepted Answer

Curved arrows show the movement of electron pairs during a reaction.

Question 12

Given the reaction $\mathrm{CH_3CH_2OH + NH_2^- \rightarrow CH_3CH_2O^- + NH_3}$, which product is the conjugate acid?

Accepted Answer

$\mathrm{NH_3}$

Question 13

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

Accepted Answer

Equilibrium favors the formation of the weaker acid and weaker base.

Question 14

If the $K_{eq}$ for an acid-base reaction is $1.0 	imes 10^4$ at 298K, what is the sign of $\Delta G^\circ$?

Accepted Answer

Negative

Question 15

Which of the following is the strongest acid based on the following $pK_a$ values: Ethanol ($pK_a = 15.9$), Acetic acid ($pK_a = 4.76$), Carbonic acid ($pK_a = 6.36$)?

Accepted Answer

Acetic acid

Question 16

Which of the following is true about the conjugate base of a strong acid?

Accepted Answer

It is a weak base.

Question 17

In the reaction $\mathrm{CH_3COOH + H_2SO_4}$, protonation occurs preferentially at which atom in acetic acid?

Accepted Answer

The carbonyl oxygen

Question 18

Which of the following is the correct relationship between $K_a$ and $pK_a$?

Accepted Answer

$pK_a = -\log_{10} K_a$

Question 19

Which of the following is a correct statement about the transition state in a reaction coordinate diagram?

Accepted Answer

It represents the highest energy point along the reaction pathway.

Question 20

Methanol ($\mathrm{CH_3OH}$) forms the most stable anion after deprotonation. What does this imply about its acidity compared to other alcohols?

Accepted Answer

Methanol is the strongest acid among alcohols.

Acids, Bases, and Acid-Base Equilibria in Organic Chemistry (Chapter 4)

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