Chapter 16 Test

Question 1

Which of the following describes a strong acid?

Answer 1

An acid that completely dissociates in water

Question 2

What is the percent dissociation of a 0.0217 M solution of chloroacetic acid, (HC2H2ClO2 )?
(Ka = 1.35 × 10^−3 )

Answer 2

22%

Question 3

A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA.

Answer 3

1.8 × 10^−3

Question 4

A 0.10 M solution of a weak base, B, is 6.4 percent ionized at 25°C. Using this information, calculate Kb for B.

Answer 4

4.1 x 10^-4

Question 5

Aluminum hydroxide can act can act as a Brønsted base or a Lewis acid. Which of the following reactions correctly shows aluminum hydroxide acting as a Lewis acid?

Answer 5

Al(OH)3(s) + OH-(aq) <==> Al(OH)4-

Question 6

A strong acid has a weak conjugate base because:

Answer 6

The conjugate base is a species that gave up a proton easily (as a strong acid), it is therefore going to be a poor proton acceptor.

Question 7

Which of the following conjugate acid / base pairs is incorrect?

Answer 7

H + / OH −

Question 8

What is the pH if the hydroxide ion concentration is 3.14 × 10^−7 M?

Answer 8

7.497

Question 9

Why is the following structure an acid?

Answer 9

The O–H bonds are easy to break

Question 10

Dimethylamine ((CH3 )2NH) is a weak base with Kb = 5.1 × 10^−4. What is the pH of a 0.60 M solution of dimethylamine and what is the percent dissociation?

Answer 10

12.23; 2.9%

Question 11

In the following equation for the dissociation of sulfuric acid in water, identify the conjugate bases.
H2SO4(aq) + H2O(l) -> HSO4-(aq) + H3O+(aq)

Answer 11

HSO4- and H2O

Question 12

The following equation for a strong acid dissolved in water at a low concentration is missing its arrow (empty box). Which arrow is the most appropriate for this reaction?
HA(aq) + H2O(l) ____ A-(aq) + H3O+(aq)

Answer 12

–>

Question 13

What is the hydrogen ion concentration of a solution with pH = −1?

Answer 13

1 × 10^1 M

Question 14

In the dissociation of the base methylamine in water shown below, identify the conjugate bases.
NH2CH3(aq) + H2O(l) <==> NH3CH3+(aq) + OH-(aq)

Answer 14

NH2CH3 and OH-

Question 15

The pOH of a solution of Ba(OH)2 is 10.66. What is the hydroxide ion concentration?

Answer 15

2.19 × 10^−11 M

Question 16

Gastric fluid or “stomach acid” has a hydroxide ion concentration of 2.2 × 10^−13 M. What is the pH of stomach acid?

Answer 16

1.34

Question 17

What is the pH of a solution of hydrochloric acid with a concentration of 1 × 10^−4 M?

Answer 17

4

Question 18

What is the [H3O+ ] in a solution with a pH of 2.34?

Answer 18

4.6 × 10^−3 M

Question 19

What is the [OH − ] in a solution with a pOH of 12.12?

Answer 19

7.6 × 10^−13 M

Question 20

What is the pOH if the hydronium ion concentration is 5.6 × 10^−2 M?

Answer 20

12.75

Question 21

Why is the value of Ka for strong acid not a useful concept?

Answer 21

Because [HA] is approximately zero.

Question 22

Sulfurous acid, H2SO3, is a weak acid. What is the pH of a 1.0 × 10^−2 M sulfurous acid solution? Use Ka = 1.0 × 10^−2, assuming that the effect of the second dissociation is not significant.

Answer 22

2.2

Question 23

Acetic acid is a weak acid with an equilibrium constant of Ka = 1.8 × 10^−5. In water, acetic acid partially dissociates to form acetate ions and hydronium ions.

What is Kb for the acetate ion?

Answer 23

5.6 × 10^−10

Question 24

For any conjugate acid-base pair at 25°C, pKa + pKb equals all of the following except:

Answer 24

7

Question 25

Which of the following is the best definition of a Lewis acid?

Answer 25

An electron-pair acceptor