Q: Which of the following is the correct formula for calculating the percent ionization of a weak acid?

$$\text{Percent Ionization} = \frac{[\mathrm{H}_3\mathrm{O}^+]_{\text{equil}}}{[\mathrm{HA}]_{\text{init}}} \times 100\%$$

Question 1

Which of the following statements best explains why antacid tablets (such as those shown in the image) are effective in relieving heartburn caused by excess stomach acid?

Accepted Answer

Antacid tablets contain bases that react with and neutralize excess HCl in the stomach, forming water and a salt.

Question 2

Which of the following equations correctly represents the neutralization reaction between hydrochloric acid and sodium hydroxide?

Accepted Answer

$$\mathrm{HCl}(aq) + \mathrm{NaOH}(aq) \rightarrow \mathrm{NaCl}(aq) + \mathrm{H}_2\mathrm{O}(l)$$

Question 3

A solution has a pH of 2.0. Which of the following best describes the solution?

Accepted Answer

It is a strongly acidic solution.

Question 4

Which of the following acids is the strongest, based on the periodic trends and molecular structure?

Accepted Answer

HI

Question 5

Which of the following best describes the difference between a strong acid and a weak acid?

Accepted Answer

A strong acid completely ionizes in water, while a weak acid only partially ionizes.

Question 6

Which of the following is the correct expression for the acid dissociation constant ($$K_a) $$for the ionization of acetic acid ($$\mathrm{CH}_3\mathrm{COOH}) in $$water?

Accepted Answer

$$K_a = \frac{[\mathrm{CH}_3\mathrm{COO}^-][\mathrm{H}_3\mathrm{O}^+]}{[\mathrm{CH}_3\mathrm{COOH}]}$$

Question 7

A 0.10 M solution of a monoprotic strong acid has a pH of:

Accepted Answer

pH = 1.0

Question 8

Which of the following best explains why the second ionization of sulfuric acid ($$\mathrm{H}_2\mathrm{SO}_4) $$must be considered when calculating the pH of a 0.10 M solution?

Accepted Answer

The second ionization constant ($$K_{a2}) is $$large enough that the second proton is released in significant amounts, affecting the total $$[\mathrm{H}_3\mathrm{O}^+].$$

Question 9

Which of the following is a Lewis acid?

Accepted Answer

$$\mathrm{BF}_3$$

Question 10

A solution has $$[\mathrm{H}_3\mathrm{O}^+] = 1.0 	imes 10$$^{-5}$$\ \mathrm{M}. $$What is the pH of the solution?

Accepted Answer

pH = 5.0

Question 11

Which of the following best describes the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 12

Which of the following is the correct formula for calculating the pOH of a solution?

Accepted Answer

$$\mathrm{pOH} = -\log[\mathrm{OH}^-]$$

Question 13

Which of the following best explains why ammonia ($$\mathrm{NH}_3) is $$considered a base according to the Brønsted–Lowry definition?

Accepted Answer

It accepts a proton from water.

Question 14

Which of the following is the correct name for $$\mathrm{HClO}_3$$?

Accepted Answer

Chloric acid

Question 15

A 0.10 M solution of $$\mathrm{Ca(OH)_2} is $$prepared. What is the $$[\mathrm{OH}^-] in $$the solution?

Accepted Answer

$$0.20\ \mathrm{M}$$

Question 16

Which of the following best describes why $$\mathrm{HF} is a $$weak acid, even though fluorine is highly electronegative?

Accepted Answer

The H–F bond is very strong, making it difficult for the hydrogen ion to dissociate.

Question 17

Which of the following is the correct formula for calculating the percent ionization of a weak acid?

Accepted Answer

$$	ext{Percent Ionization} = \frac{[\mathrm{H}_3\mathrm{O}^+]_{	ext{equil}}}{[\mathrm{HA}]_{	ext{init}}} 	imes 100\%$$

Question 18

Which of the following best describes the effect of adding an electron-withdrawing group to an amine base?

Accepted Answer

It decreases the base strength by making the nitrogen less able to accept a proton.

CHEM 131 Chapter 17: Acid-Base Equilibria: Properties, Definitions, Calculations, and Applications

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