Chapter 16 Flashcards


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Acid Basic Equilibria
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chemistry 2
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1

Which solution below has the highest concentration of hydronium ions?Answers:

pH = 3.0

pH = 10

pH = 7.0

pH = 6.4

pH = 11.2

Selected Answer:

pH = 3.0

2

Ammonia is a ________.

Answers:

weak acid

strong base

weak base

strong acid

salt

Selected Answer: weak base

3

Classify the following compounds as weak acids (W) or strong acids (S):

hypochlorous acid perchloric acid chloric acid

Answers:

W S S

S S S

S W W

W W W

W S W

Selected Answer:

W S S

4

Which of the following ions will act as a weak base in water?

Answers:

HS-

F-

NO2-

ClO-

All of the above will act as a weak base in water.

Selected Answer:

All of the above will act as a weak base in water.

5

What is the conjugate acid of NH3?

Answers:

NH3

NH2+

NH3+

NH4+

NH4OH

Selected Answer:

NH4+

6

What is the pH of an aqueous solution at 25.0 °C in which [OH-] is 0.0030 M?

Answers:

5.81

-11.48

2.52

-2.52

11.48

Selected Answer:

11.48

7

What is the pOH of an aqueous solution at 25.0 °C in which [OH-] is 0.0010 M?

Answers:

11

-3

3

-116.91

Selected Answer:

3

8

What is the conjugate acid of CO32- ?

Answers:

CO22-

HCO22-

H2CO3

HCO3-

none of the above

Selected Answer:

HCO3-

9

The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0 °C is 4.48. What is the value of Ka for HBrO?

Answers:

2.0 × 10-9

1.1 × 10-9

6.0 × 10-5

3.3 × 10-5

3.0 × 104

Selected Answer:

2.0 × 10-9

10

An aqueous solution of ________ will produce a neutral solution.

Answers:

LiNO3

NaNO2

KF

Rb2CO3

NH4NO3

Selected Answer:

LiNO3

11

Calculate the pOH of 0.606 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that Kb for aniline is 3.83 × 10-4.

Answers:

1.82

12.18

5.40

8.60

12.42

Selected Answer:

8.60

12

Of the following substances, an aqueous solution of ________ will form basic solutions.

NaHS Cu(NO3)2 KHCO3 NaF

Answers:

NaHS, Cu(NO3)2

KHCO3, NaHS

NaF only

NaF, KHCO3

NaHS, KHCO3 and NaF

Selected Answer:

NaHS, KHCO3 and NaF

13

The Ka for HCN is 4.9 × 10-10. What is the value of Kb for CN-?

Answers:

2.0 × 10-5

4.0 × 10-6

4.9 × 104

4.9 × 10-24

2.0 × 109

Selected Answer:

2.0 × 10-5

14

Which one of the following is the weakest acid?

Answers:

HF (Ka = 6.8 × 10-4)

HClO (Ka = 3.0 × 10-8)

HNO2 (Ka = 4.5 × 10-4)

HCN (Ka = 4.9 × 10-10)

Acetic acid (Ka = 1.8 × 10-5)

Selected Answer:

HCN (Ka = 4.9 × 10-10)

15

What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydronium ion?

Answers:

8.400

5.600

9.000

3.980

7.000

Selected Answer:

8.400

16

Determine the pH of a 0.15 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.

Answers:

0.82

5.83

8.17

5.01

1.17

Selected Answer:

8.17

17

According to the Arrhenius concept, an acid is a substance that ________.

Answers:

is capable of donating one or more H+

causes an increase in the concentration of H+ in aqueous solutions

can accept a pair of electrons to form a coordinate covalent bond

reacts with the solvent to form the cation formed by autoionization of that solvent tastes bitter

Selected Answer:

causes an increase in the concentration of H+ in aqueous solutions

18

HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0 °C. The Ka of HZ is ________.

Answers:

1.2 × 10-5

6.9 × 10-9

1.4 × 10-10

9.9 × 10-2

2.8 × 10-12

Selected Answer:

6.9 × 10-9

19

Which solution will be the most basic?

Answers:

0.10 M Ba(OH)2

0.10 M KOH

0.10 M H2O

0.10 M CH3OH

Selected Answer:

0.10 M Ba(OH)2

20

Which one of the following statements regarding Kw is false?

Answers:

pKw is 14.00 at 25 °C.

The value of Kw is always 1.0 × 10-14.

Kw changes with temperature.

The value of Kw shows that water is a weak acid.

Kw is known as the ion product of water.

Selected Answer:

The value of Kw is always 1.0 × 10-14.

21

Which of the following aqueous solutions has the lowest [OH-]?

Answers:

a solution with a pH of 3.0

a 1 × 10-4 M solution of HNO3

a solution with a pOH of 12.0

pure water

a 1 × 10-3 M solution of NH4Cl

Selected Answer:

a solution with a pOH of 12.0

22

The pH of a 0.25 M aqueous solution of hydrofluoric acid, HF, at 25.0 °C is 2.03. What is the value of Ka for HF?

Answers:

2.0 × 10-9

1.1 × 10-9

6.0 × 10-5

3.5 × 10-4

Selected Answer:

3.5 × 10-4

23

Of the following substances, an aqueous solution of ________ will form basic solutions.

NH4Cl Cu(NO3)2 K2CO3 NaF

Answers:

NH4Cl, Cu(NO3)2

K2CO3, NH4Cl

NaF only

NaF, K2CO3

NH4Cl only

Selected Answer:

NaF, K2CO3

24

Calculate the concentration (in M) of hydronium ions in a solution at 25.0 °C with a pOH of 4.223.

Answers:

5.98 × 10-5

1.67 × 10-10

1.67 × 104

5.99 × 10-19

1.00 × 10-7

Selected Answer:

1.67 × 10-10

25

A 0.15 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 5.35. The value of Ka for HA is ________.

Answers:

3.0 × 10-5

1.8 × 10-5

7.1 × 10-9

1.3 × 10-10

3.3 × 104

Selected Answer:

1.3 × 10-10

26

Classify the following compounds as weak acids (W) or strong acids (S):

hydrocyanic acid hydrofluoric acid phenol

Answers:

W W W

S S S

S W W

W S S

W S W

Selected Answer:

W W W

27

Of the compounds below, a 0.1 M aqueous solution of ________ will have the highest pH.

Answers:

KCN, Ka of HCN = 4.0 × 10-10

NH4NO3, Kb of NH3 = 1.8 × 10-5

NaOAc, Ka of HOAc = 1.8 × 10-5

NaClO, Ka of HClO = 3.2 × 10-8

NaHS, Kb of HS- = 1.8 × 10-7

Selected Answer:

KCN, Ka of HCN = 4.0 × 10-1

28

Calculate the pH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.

Answers:

1.94

4.29

7.00

14.0

Selected Answer:

-log(1.94 x 10-10M = 9.71

29

Classify the following compounds as weak acids (W) or strong acids (S):

hypochlorous acid perchloric acid chloric acid

Answers:

W S S

S S S

S W W

W W W

W S W

Selected Answer:

W S S

30

Which of the following aqueous solutions has the lowest [OH-]?

Answers:

a solution with a pH of 3.0

a 1 × 10-4 M solution of HNO3

a solution with a pOH of 12.0

pure water

a 1 × 10-3 M solution of NH4Cl

Selected Answer:

a solution with a pOH of 12.0

31

What is the conjugate acid of CO32- ?

Answers:

CO22-

HCO22-

H2CO3

HCO3-

none of the above

Selected Answer:

HCO3-

32

Determine the pOH of a 0.10 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.

Answers:

1.00

5.92

8.08

5.01

1.58

Selected Answer:

5.92

33

Classify the following compounds as weak acids (W) or strong acids (S):

nitrous acid hydrochloric acid hydrofluoric acid

Answers:

W W W

S S S

S W W

W S S

W S W

Selected Answer:

W S W

34

The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25.0 °C. Calculate the pH of a 0.0385 M hypochlorous acid solution.

Answers:

3.05

9.53

4.47

6.52

-3.05

Selected Answer:

4.47

35

The pH of a 0.30 M solution of a weak acid is 2.67. What is the Ka for this acid?

Answers:

2.1 × 10-4

4.4 × 10-4

1.5 × 10-4

6.6 × 10-4

none of the above

Selected Answer:

none of the above

36

Calculate the pOH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.

Answers:

1.94

4.29

7.00

14.0

9.71

Selected Answer:

4.29

37

Calculate the pOH of a 0.0727 M aqueous sodium cyanide solution at 25.0 °C. Kb for CN- is
4.9 × 10-10.

Answers:

9.33

10.00

5.22

1.14

8.78

Selected Answer:

5.22

38

The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25.0 °C. Calculate the pH of a 0.0385 M hypochlorous acid solution.

Answers:

3.05

9.53

4.47

6.52

-3.05

Selected Answer:

4.47

39

The conjugate acid of CH3NH2 is ________.

Answers:

CH3NH2

CH3NH3+

CH3NH2+

CH3NH+

Selected Answer:

CH3NH3+

40

A 0.0035 M aqueous solution of a particular compound has pH = 2.46. The compound is ________.

Answers:

a weak base

a weak acid

a strong acid

a strong base

a salt

Selected Answer:

a strong acid

41

Calculate the concentration (in M) of hydroxide ions in a solution at 25.0 °C with a pOH of 4.223.

Answers:

5.98 × 10-5

1.67 × 10-10

1.67 × 104

5.99 × 10-19

1.00 × 10-7

Selected Answer:

5.98 × 10-5

42

What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydronium ion?

Answers:

8.400

5.600

9.000

3.980

7.000

Selected Answer:

8.400

43

Which of the following aqueous solutions has the highest [OH-]?

Answers:

a solution with a pH of 3.0

a 1 × 10-4 M solution of HNO3

a solution with a pOH of 12.0

pure water

a 1 × 10-3 M solution of NH4Cl

Selected Answer:

pure water

44

A Br∅nsted-Lowry base is defined as a substance that ________.

Answers:

increases [H+] when placed in H2O

decreases [H+] when placed in H2O

increases [OH-] when placed in H2O

acts as a proton acceptor

acts as a proton donor

Selected Answer:

acts as a proton acceptor

45

An aqueous solution of ________ will produce a neutral solution.

Answers:

LiNO3

NaNO2

KF

Rb2CO3

NH4NO3

Selected Answer:

LiNO3

46

A 0.0035 M aqueous solution of a particular compound has pH = 2.46. The compound is ________.

Answers:

a weak base

a weak acid

a strong acid

a strong base

a salt

Selected Answer:

a strong acid

47

Determine the pH of a 0.35 M aqueous solution of CH3NH2 (methylamine). The Kb of methylamine is 4.4 × 10-4.

Answers:

10.00

3.86

12.09

1.96

13.24

Selected Answer:

12.09

48

Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 3.00.

Answers:

1.0 × 10-3

11.00

1.0 × 10-11

3.0 × 10-14

1.1 × 10-13

Selected Answer:

1.0 × 10-3

49

What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?

Answers:

8.40

5.60

9.00

3.98

7.00

Selected Answer:

5.60

50

What is the conjugate acid of NH3?

Answers:

NH3

NH2+

NH3+

NH4+

NH4OH

Selected Answer:

NH4+