Q: Which of the following compounds can act as both a Brønsted acid and a Brønsted base?

$$\text{CH}_3\text{OH} ($$methanol)

Question 1

Which of the following statements best explains why carboxylic acids are generally stronger acids than alcohols?

Accepted Answer

Carboxylic acids have delocalized electrons in their conjugate base, stabilizing the negative charge.

Question 2

Given the following acid-base reaction, which direction will the equilibrium favor? 
$$	ext{CH}_3	ext{COOH} + 	ext{NH}_3 \rightleftharpoons 	ext{CH}_3	ext{COO}^- + 	ext{NH}_4^+$$
Given $$pK_a$$ values: acetic acid = 4.8, ammonium ion = 9.4.

Accepted Answer

The equilibrium favors the products because the weaker acid is formed.

Question 3

Which of the following compounds will have the most delocalized electrons in its conjugate base?

Accepted Answer

$$	ext{CH}_3	ext{COOH}$$

Question 4

Which of the following factors does NOT increase the acidity of a compound?

Accepted Answer

Decreasing the electronegativity of a substituent near the acidic proton.

Question 5

A buffer solution is prepared using acetic acid ($$pK_a = 4.76) $$and sodium acetate. If the pH of the solution is 5.76, what is the ratio $$\left( \frac{[	ext{A}^-]}{[	ext{HA}]} ight)$$ according to the Henderson–Hasselbalch equation?

Accepted Answer

10

Question 6

Which of the following best describes a Lewis acid?

Accepted Answer

A species that accepts a share in an electron pair.

Question 7

Which of the following statements is true regarding the solubility of organic compounds in water and diethyl ether?

Accepted Answer

Neutral compounds dissolve in diethyl ether, while charged compounds dissolve in water.

Question 8

Which of the following acids has the lowest $$pK_a$$ value and is therefore the strongest acid?

A. $$	ext{CH}_3	ext{OH}$$ ($$pK_a = 15.5)
B$$. $$	ext{CH}_3	ext{COOH}$$ ($$pK_a = 4.76)
C$$. $$	ext{CH}_3	ext{NH}_2$$ ($$pK_a = 40)
D$$. $$	ext{H}_2	ext{O}$$ ($$pK_a = 15.7)$$

Accepted Answer

B

Question 9

Which of the following best explains why the acidity of hydrohalic acids increases from HF to HI?

Accepted Answer

The size of the halogen increases down the group, making the H–X bond weaker.

Question 10

Which of the following statements about the effect of substituents on acid strength is correct?

Accepted Answer

A more electronegative substituent closer to the acidic proton increases acid strength.

Question 11

Which of the following is the correct expression for the acid dissociation constant $$K_a$$ for a generic acid $$HA in $$water?

Accepted Answer

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

Question 12

Which of the following best describes the relationship between acid strength and the stability of its conjugate base?

Accepted Answer

The stronger the acid, the more stable its conjugate base.

Question 13

Which of the following compounds can act as both a Brønsted acid and a Brønsted base?

Accepted Answer

$$	ext{CH}_3	ext{OH} ($$methanol)

Question 14

Which of the following is the correct form of the Henderson–Hasselbalch equation?

Accepted Answer

$$	ext{pH} = 	ext{p}K_a - \log \left( \frac{[	ext{HA}]}{[	ext{A}^-]} ight)$$

Question 15

Which of the following best explains why protonated alcohols are stronger acids than protonated amines?

Accepted Answer

Oxygen is more electronegative than nitrogen.

Question 16

Which of the following is a real-world consequence of acid rain, which is caused by strong acids in the environment?

Accepted Answer

Damage to aquatic ecosystems and forest dieback.

Question 17

Which of the following statements about buffer solutions is correct?

Accepted Answer

A buffer solution contains an acid and its conjugate base.

Question 18

Which of the following is the strongest acid?

A. $$	ext{CH}_4
B$$. $$	ext{NH}_3
C$$. $$	ext{H}_2	ext{O}
D$$. $$	ext{HF}$$

Accepted Answer

D

Acids and Bases in Organic Chemistry: Concepts, Equilibria, and Factors Affecting Strength

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