Question 1

According to the Bronsted-Lowry definition, which of the following statements is TRUE?

Accepted Answer

A base is a substance that accepts a proton ($$\mathrm{H^+}) $$from another substance.

Question 2

Which of the following compounds is NOT an acid?

Accepted Answer

$$\mathrm{$$CCl_4$$}$$

Question 3

In the following reaction, identify the conjugate acid:

$$\mathrm{NH_3$ + H_2O \rightarrow NH_4$^+ + OH^-}$$

Accepted Answer

$$\mathrm{NH_4$^+}$$

Question 4

Which of the following best describes the acid dissociation constant ($$K_a$$)?

Accepted Answer

$$K_a is $$the equilibrium constant for the dissociation of an acid in water.

Question 5

Given the following acids and their $$K_a$$ values, which is the strongest acid?

A: $$K_a = 1.0 	imes 10$$^{-1}$$
B: K_a = 1.7$$ 	imes $$10^{-5}
C$$: $$K_a = 1.7 	imes 10$$^{-9}$$
D: K_a = 1.0$$ 	imes $$10^{-7}$$

Accepted Answer

A

Question 6

Which of the following statements about $$pK_a is $$CORRECT?

Accepted Answer

$$pK_a is $$defined as $$-\log K_a.$$

Question 7

Which of the following functional groups is associated with the lowest (most acidic) $$pK_a$$ value?

Accepted Answer

Carboxylic acid ($$-COOH)$$

Question 8

Given the $$pK_a$$ values of their conjugate acids, which is the weaker base?

$$\mathrm{CH_3NH_2}$$ ($$pK_a of $$conj. acid $$\approx 10) or$$ $$\mathrm{CH_3CH_2NH_2}$$ ($$pK_a of $$conj. acid $$\approx 11)$$

Accepted Answer

$$\mathrm{CH_3NH_2}$$

Question 9

Which of the following best explains why water ($$\mathrm{H_2O}) $$can act as both an acid and a base?

Accepted Answer

Water contains both a proton and a lone pair of electrons.

Question 10

Which of the following is the correct $$pK_a$$ value for a typical carboxylic acid group?

Accepted Answer

$$\approx 5$$

Question 11

In a reaction between $$\mathrm{CH_3OH}$$ and $$\mathrm{NH_3$}$$, $$\mathrm{CH_3OH}$$ acts as an acid. What is the product formed when $$\mathrm{CH_3OH}$$ donates a proton?

Accepted Answer

$$\mathrm{CH_3O^-}$$

Question 12

Which of the following statements about conjugate acid-base pairs is TRUE?

Accepted Answer

The stronger the acid, the weaker its conjugate base.

Question 13

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

Accepted Answer

$$pK_a = -\log K_a$$

Question 14

Which of the following is most likely to be protonated (i.e., is the strongest base)?

A. $$\mathrm{OH^-}
B$$. $$\mathrm{NH_2$^-}
C$$. $$\mathrm{CH_3COO^-}
D$$. $$\mathrm{HCOO^-}$$

Accepted Answer

$$\mathrm{NH_2$^-}$$

Question 15

A solution contains $$\mathrm{HCl}$$ and $$\mathrm{CH_3COOH}. $$Which acid will donate a proton first, and why?

Accepted Answer

$$\mathrm{HCl}$$, because it is a stronger acid with a lower $$pK_a.$$

Question 16

Which of the following best describes the effect of a lower $$pK_a$$ value for an acid?

Accepted Answer

The acid is stronger and more likely to donate a proton.

Question 17

Which of the following is the correct $$pK_a$$ value for a typical alcohol group?

Accepted Answer

$$\approx 15$$

Question 18

If the $$pK_a of$$ $$\mathrm{H_2O} is 15.7 $$and the $$pK_a of$$ $$\mathrm{CH_3OH} is 15.5$$, which is the stronger acid?

Accepted Answer

$$\mathrm{CH_3OH}$$

Question 19

Which of the following best explains why amines ($$-NH_2$) are considered basic functional groups in organic chemistry?

Accepted Answer

Amines have a lone pair of electrons on nitrogen that can accept a proton.

Question 20

In a real-world scenario, why is it important for a physician to know the $$pK_a$$ values of drugs administered to a patient?

Accepted Answer

Because $$pK_a$$ values affect the solubility and ionization of drugs at physiological pH, influencing absorption and activity.

Acids and Bases: Central Concepts in Organic Chemistry

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