Chapter 16 2 What 25c For The Following Equilibrium

66. Which of the following equilibria best represents the hydrolysis reaction that occurs in an

aqueous solution of NH4Cl?

A)

Cl–(aq) + H3O+(aq) HCl(aq) + H2O(l)

B)

NH4+(aq) + H2O(l) NH3(aq) + H3O+(aq)

C)

NH4+(aq) + OH–(aq) NH3(aq) + H2O(l)

D)

Cl–(aq) + H2O(l) HCl(aq) + OH–(aq)

E)

NH4+(aq) + Cl–(aq) NH4Cl(s)

67. Which of the following equilibria best represents the hydrolysis reaction that occurs in an

aqueous solution of KNO2?

A)

NO2–(aq) + H2O(l) HNO3(aq) + 2H+(aq)

B)

NO2–(aq) + H2O(l) HNO2(aq) + OH–(aq)

C)

NO2–(aq) + H3O+(aq) HNO2(aq) + H2O(l)

D)

K+(aq) + NO2–(aq) + H2O(l) KOH(aq) + HNO2(aq)

E)

K+(aq) + H2O(l) KOH(aq) + H+(aq)

68. Which of the following statements is true concerning a 0.1 M solution of Na2S and a 0.1 M

solution of NaHS? For H2S, Ka1 = 1.0  10–7 and Ka2 = 1.3  10–13.

A)

Both solutions are neutral.

B)

The sodium hydrogen sulfide solution is the more basic.

C)

Both solutions have the same pH.

D)

The sodium sulfide solution is the more basic.

E)

Both the solutions are acidic.

Test Bank General Chemistry, 10th edition 22

69. Which of the following solutions has the highest hydroxide-ion concentration?

A)

0.10 M NH4ClO4

B)

0.10 M NaI

C)

0.10 M NaNO3

D)

0.10 M NH4Cl

E)

0.10 M NaCN

70. Given the following, what will be the approximate equilibrium pH of an aqueous solution of

ammonium acetate, NH4CH3CO2?

NH4+

Ka = 5.69 x10–10

CH3CO2−

Kb = 5.71 x10–10

A)

very basic

B)

very acidic

C)

nearly neutral

71. Given the following, what will be the approximate equilibrium pH of an aqueous solution of

ammonium cyanide, NH4CN?

NH4+

Ka = 5.69 x10–10

HCN

Ka = 6.2 x10–10

A)

slightly basic

B)

slightly acidic

C)

nearly neutral

72. The amphiprotic anion monohydrogenphosphate acts as both an acid and a base in aqueous

solution. Given the following acid-ionization and base-hydrolysis constants, what will be

the approximate equilibrium pH of an aqueous solution of sodium

monohydrogenphosphate?

Ka =

4.22 10−13

Kb =

1.58 10−7

Test Bank General Chemistry, 10th edition 23

A)

basic

B)

acidic

C)

neutral

73. Which sodium salt(s) of an amphiprotic ion will produce an acidic solution when added to

pure water?

1.

NaHSO4 (Ka = 1.03 x10-2; Kb = 9.71 x10–13)

2.

NaHCO3 (Ka = 4.69 x10–11; Kb = 2.24 x10-8)

3.

NaHSO3 (Ka = 6.73 x10-8; Kb = 7.19 x10–13)

A)

1 only

B)

2 only

C)

3 only

D)

1 and 3

E)

1 and 2

74. Which of the following salts will produce an acidic solution when added to pure water?

A)

Cs2CO3

B)

NaF

C)

KCN

D)

Al(NO3)3

E)

Li2S

75. Which of the following salts is most likely to form an aqueous solution having the pH

shown in the figure below?

Test Bank General Chemistry, 10th edition 24

A)

Na2CO3

B)

RbF

C)

NH4Cl

D)

Zn(NO3)2

E)

KCl

76. Which of the following salts is most likely to form an aqueous solution having the pH

shown in the figure below?

A)

NH4Cl

B)

NaBr

C)

K2CO3

D)

RbCN

E)

LiNO3

77. Which of the following salts is most likely to form an aqueous solution having the pH

shown in the figure below?

Test Bank General Chemistry, 10th edition 25

A)

KCl

B)

Zn(NO3)2

C)

NaCN

D)

NH4Cl

E)

LiBr

78. Which of the following salts will produce a neutral solution when added to pure water?

A)

LiHCO3

B)

NH4NO3

C)

Na2SO4

D)

RbNO2

E)

KNO3

79. Which of the following salts forms an acidic aqueous solution?

A)

NaNO2

B)

KCH3CO2

C)

Rb2O

D)

FeCl3

E)

NaCN

80. Consider the reaction NH3(aq) + H2O(l) NH4+(aq) + OH–(aq). Kb for NH3 is 1.8  10–

5 at 25°C. What is Ka for the NH4+ ion at 25°C?

A)

5.6  104

B)

5.6  10–10

C)

1.8  10–5

D)

7.2  10–12

E)

9.2  10–8

81. What is Ka at 25°C for the following equilibrium?

C6H5NH3+(aq) + H2O(l) C6H5NH2(aq) + H3O+(aq)

Kb (C6H5NH2) = 4.2  10–10 at 25°C.

A)

4.2  10–4

B)

2.4  103

C)

4.2  10–10

D)

4.2  104

E)

2.4  10–5

82. The Ka for hydrofluoric acid is 6.8  10–4. What is Kb for the fluoride ion?

A)

1.5  10–11

B)

6.8  10–4

C)

1.5  103

D)

6.8  1010

E)

6.8  10–18

83. What is Kb for the following equilibrium? Ka for HNO2 is 5.0  10–4.

NO2–(aq) + H2O(l) HNO2(aq) + OH–(aq)

A)

2.0  10–4

B)

5.0  10–4

C)

5.0  1010

D)

5.0  1018

E)

2.0  10–11

Test Bank General Chemistry, 10th edition 27

84. What is Ka for the methylammonium cation, CH3NH3+, at 25°C? (Kb for

CH3NH2 = 4.4  10–4 at 25°C.)

A)

1.0  10–7

B)

4.4  1010

C)

4.4  10–18

D)

2.3  10–11

E)

4.4  10–4

85. The two acid-ionization constants for sulfurous acid, H2SO3, are 1.3  10–2 and 6.3  10–8 at

25°C. What is Kb for the HSO3– ion?

A)

6.3  10–8.

B)

6.2  10–22.

C)

7.7  10–13.

D)

1.3  10–2.

E)

8.2  10–10.

86. What is Kc for the following equilibrium? For phosphoric acid (H3PO4), Ka1 = 6.9  10–3,

Ka2 = 6.2  10–8, and Ka3 = 4.8  10–13.

HPO42–(aq) + OH–(aq) PO43–(aq) + H2O(l)

A)

7.3  10–16

B)

6.4  10–23

C)

491

D)

48

E)

2.3  10–35

87. What is the pH of a 0.38 M solution of sodium propionate, NaC3H5O2, at 25°C? (For

propionic acid, HC3H5O2, Ka = 1.3  10–5 at 25°C.)

A)

6.11

B)

4.77

C)

11.10

D)

7.89

E)

9.23

88. What is the hydroxide-ion concentration in a 0.22 M solution of Na2CO3? For carbonic

acid, Ka1 = 4.2  10–7 and Ka2 = 4.8  10–11. (Kw = 1.0  10–14)

A)

6.8  10–3 M

B)

2.0  10–4 M

C)

7.2  10–5 M

D)

4.2  10–9 M

E)

3.2  10–6 M

89. In a 0.10 M solution of sodium hydrogen sulfate, the HSO4– ion is 29% dissociated. What is

Ka2 for H2SO4?

A)

2.4  10–1

B)

1.2  10–2

C)

1.0  10–2

D)

8.4  10–3

E)

2.0  10–2

90. What is the pH of a solution prepared by adding 0.490 g of ammonium iodide to 155 mL of

water? Kb of NH3 is 1.8  10–5.

A)

5.46

B)

3.21

C)

7.00

D)

8.54

E)

10.79

Test Bank General Chemistry, 10th edition 29

91. What is the pOH of a solution prepared by adding 1.12 g of ammonium iodide to 105 mL of

water? Kb of NH3 is 1.8  10–5.

A)

2.94

B)

11.06

C)

7.00

D)

5.19

E)

8.81

92. What is the pH of a solution prepared by adding 1.67 g of potassium nitrite to 185 mL of

water? Ka of HNO2 is 4.5  10–4.

A)

5.82

B)

2.18

C)

7.00

D)

11.82

E)

8.18

93. What is the pOH of a solution prepared by adding 1.42 g of sodium nitrite to 125 mL of

water? Ka of HNO2 is 4.5  10–4.

A)

11.92

B)

2.08

C)

8.28

D)

7.00

E)

5.72

94. What is the hydroxide-ion concentration of a 0.250 M sodium oxalate (Na2C2O4) solution?

For oxalic acid (H2C2O4), Ka1 = 5.6  10–2 and Ka2 = 5.1  10–5.

A)

7.0  10–6 M

B)

1.0  10–7 M

C)

9.4  10–2 M

D)

3.5  10–3 M

E)

2.1  10–7 M

Test Bank General Chemistry, 10th edition 30

95. Which of the following substances, if added to a 0.10 M HC2H3O2 solution, would not

increase the hydronium-ion concentration?

A)

Na2CO3(s)

B)

NaHSO4(s)

C)

H2C2O4(s)

D)

HF(l)

E)

HCl(g)

96. What will happen if a small amount of hydrochloric acid is added to a 0.1 M solution of HF?

A)

The percent ionization of HF will decrease.

B)

Ka for HF will increase.

C)

Ka for HF will decrease.

D)

The percent ionization of HF will remain unchanged.

E)

The percent ionization of HF will increase.

97. What will happen if a small amount of sodium hydroxide is added to a 0.1 M solution of

ammonia?

A)

Kb for ammonia will decrease.

B)

The percent ionization of ammonia will increase.

C)

Kb for ammonia will increase.

D)

The percent ionization of ammonia will decrease.

E)

The percent ionization of ammonia will remain unchanged.

98. 15.0 mL of 0.50 M HCl is added to a 100.0-mL sample of 0.377 M HNO2 (Ka for

HNO2 = 4.0  10–4). What is the equilibrium concentration of NO2– ions?

A)

3.3  10–1 M

B)

1.3  10–4 M

C)

4.5  10–2 M

D)

2.0  10–3 M

E)

none of these

99. When equal volumes of solutions are mixed, as shown below, what will be the relative pH

values of the resulting solutions?

A)

I < V < III < II < IV

B)

V < I < IV < II < III

C)

III < I < IV = V < II

D)

I = V < III < II < IV

E)

III < I = V < III < IV < II

100. For a solution equimolar in HCN and NaCN, which statement is false?

A)

[H+] is equal to Ka.

B)

[H+] is larger than it would be if only the HCN were in solution.

C)

Addition of NaOH will increase [CN–] and decrease [HCN].

D)

Addition of more NaCN will shift the acid-dissociation equilibrium of HCN to the

left.

E)

Addition of more HCN will shift the acid-dissociation equilibrium of HCN to the

right.

Test Bank General Chemistry, 10th edition 32

101. What is the pH of the solution if 0.021 g of sodium fluoride is added to 130.0 mL of a

0.098 M HF solution? Ka for HF is 6.8  10–4.

A)

2.21

B)

5.08

C)

2.88

D)

2.11

E)

4.85

102. What is the equilibrium fluoride ion concentration of a solution that initially consists of 0.47

M HF and 0.418 M HCl? Ka for HF is 6.8  10–4.

A)

7.7 10−4

M

B)

6.0 10−4

M

C)

3.4 10−3

M

D)

1.8 10−2

M

E)

3.8 10−2

M

103. Calculate the pH of a solution that is 2.00 M HF, 1.00 M NaOH, and 0.690 M NaF.

(Ka = 6.8  10–4)

A)

3.40

B)

2.94

C)

3.17

D)

2.71

E)

none of these

104. Which of the following combinations is not suitable for making a buffer?

A)

HClO4 and NaClO4

B)

NaH2PO4 and Na2HPO4

C)

NH4Cl and NH3

D)

H3PO4 and NaH2PO4

E)

Na2CO3 and NaHCO3

105. Which of the following would be the best mole ratio of conjugate acid to conjugate base for

a large buffer capacity?

A)

100:1

B)

1:1

C)

1:100

D)

1:10

E)

10:1

106. Which of the following is the most effective buffer system for a pH value of 4.45?

A)

H2CO3/HCO3– (Ka1 for H2CO3 is 4.3  10–7)

B)

HCO3–/CO32– (Ka2 for H2CO3 is 4.8  10–11)

C)

H2S/HS– (Ka1 for H2S is 8.9  10–8)

D)

HC2O4–/C2O42– (Ka2 for H2C2O4 is 5.1  10–5)

E)

H3PO4/H2PO4– (Ka1 for H3PO4 is 6.9  10–3)

107. Which of the following will give a buffer with a pH near 4.76 when the acid and conjugate

base are mixed in equimolar proportions?

Acid

Ka

NH4+ (from ammonia)

5.69  10–10

HC2H3O2 (acetic acid)

1.75  10-5

HF (hydrofluoric acid)

6.8  10-4

CH3CH2NH3+ (from

ethylamine)

2.12  10–11

A)

acetic acid

B)

hydrofluoric acid

C)

ethylamine

D)

none

E)

ammonia