Deck 17: Additional Aspects of Aqueous Equilibria

Question 1

Of the following solutions, which has the greatest buffering capacity?

A)0.543 M NH₃ and 0.555 M NH₄Cl
B)0.087 M NH₃ and 0.088 M NH₄Cl
C)0.234 M NH₃ and 0.100 M NH₄Cl
D)0.100 M NH₃ and 0.455 M NH₄Cl
E)They are all buffer solutions and would all have the same capacity.

Answer 1

0.543 M NH₃ and 0.555 M NH₄Cl

Question 2

Which of the following could be added to a solution of potassium fluoride to prepare a buffer?

A)sodium hydroxide
B)potassium acetate
C)hydrochloric acid
D)sodium fluoride
E)ammonia

Answer 2

hydrochloric acid

Question 3

Which one of the following pairs cannot be mixed together to form a buffer solution?

A)HONH₂, HONH₃Cl
B)NaCl, HCl
C)RbOH, HF
D)KOH, HNO₂
E)H₂SO₃, KHSO₃

Answer 3

NaCl, HCl

Question 4

What change will be caused by addition of a small amount of HCl to a solution containing fluoride ions and hydrogen fluoride?

A)The concentration of hydronium ions will increase significantly.
B)The concentration of fluoride ions will increase as will the concentration of hydronium ions.
C)The concentration of hydrogen fluoride will decrease and the concentration of fluoride ions will increase.
D)The concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will increase.
E)The fluoride ions will precipitate out of solution as its acid salt.

Question 5

A solution containing which one of the following pairs of substances will be a buffer solution?

A)NaI, HI
B)KBr, HBr
C)RbCl, HCl
D)CsF, HF
E)none of the above

Question 6

The addition of hydrochloric acid and ________ to water produces a buffer solution.

A)HC₆H₅O
B)NaOH
C)NH₃
D)HNO₃
E)NaNO₃

Question 7

Which of the following could be added to a solution of acetic acid to prepare a buffer?

A)sodium acetate only
B)sodium acetate or sodium hydroxide
C)nitric acid only
D)hydrofluoric acid or nitric acid
E)sodium hydroxide only

Question 8

The primary buffer system that controls the pH of the blood is the ________ buffer system.

A)carbon dioxide, carbonate
B)carbonate, bicarbonate
C)carbonic acid, carbon dioxide
D)carbonate, carbonic acid
E)carbonic acid, bicarbonate

Question 9

A solution containing which one of the following pairs of substances will be a buffer solution?

A)KI, HI
B)AgBr, HBr
C)CuCl, HCl
D)CsI, HI
E)none of the above

Question 10

The addition of sodium hydroxide and ________ to water produces a buffer solution.

A)HCl
B)NaC₂H₃O₂
C)NaF
D)NH₃
E)none of the above

Question 11

The Henderson-Hasselbalch equation is ________.

A)[H⁺] = K_a +
B)pH = pK_a - log
C)pH = pK_a + log
D)pH = pK_a + log
E)pH = log

Question 12

Which one of the following pairs cannot be mixed together to form a buffer solution?

A)NH₃, NH₄Cl
B)NaC₂H₃O₂, HCl (C₂H₃O₂^- = acetate)
C)RbOH, HBr
D)KOH, HF
E)H₃PO₄, KH₂PO₄

Question 13

The addition of hydrofluoric acid and ________ to water produces a buffer solution.

A)HCl
B)NaNO₃
C)NaCl
D)NaOH
E)NaBr

Question 14

The addition of hydrochloric acid and ________ to water produces a buffer solution.

A)HC₆H₅O
B)NaOH
C)NaCl
D)C₂H₅NH₂
E)none of the above

Question 15

In a solution, when the concentrations of a weak acid and its conjugate base are equal, ________.

A)the system is not at equilibrium
B)the buffering capacity is significantly decreased
C)the -log of the [H⁺] and the -log of the K_a are equal
D)All of the above are true.

Question 16

Which one of the following pairs cannot be mixed together to form a buffer solution?

A)C₅H₅N, C₅H₅NHCl
B)HC₂H₃O₂, NaOH (C₂H₃O₂^- = acetate)
C)KOH, HI
D)NH₂CH₃, HCl
E)NaClO, HNO₃

Question 17

Which of the following could be added to a solution of acetic acid to prepare a buffer?

A)sodium hydroxide
B)hydrochloric acid
C)nitric acid
D)more acetic acid
E)None of the above can be added to an acetic acid solution to prepare a buffer.

Question 18

Of the following solutions, which has the greatest buffering capacity?

A)0.521 M HC₂H₃O₂ and 0.217 M NaC₂H₃O₂
B)0.821 M HC₂H₃O₂ and 0.713 M NaC₂H₃O₂
C)0.365M HC₂H₃O₂ and 0.497 M NaC₂H₃O₂
D)0.121 M HC₂H₃O₂ and 0.116 M NaC₂H₃O₂

Question 19

What are the principal organs that regulate the pH of the carbonic acid-bicarbonate buffer system in the blood?

A)kidneys, liver
B)lungs, kidneys
C)spleen, liver
D)lungs, skin
E)brain stem, heart

Question 20

Which of the following could be added to a solution of sodium acetate to produce a buffer?

A)acetic acid only
B)acetic acid or hydrochloric acid
C)hydrochloric acid only
D)potassium acetate only
E)sodium chloride or potassium acetate

Question 21

The molar solubility of ________ is not affected by the pH of the solution.

A)Na₃PO₄
B)NaF
C)KNO₃
D)AlCl₃
E)MnS

Question 22

Calculate the pH of a solution prepared by dissolving 0.150 mol of benzoic acid and 0.300 mol of sodium benzoate in water sufficient to yield 1.00 L of solution. The K_a of benzoic acid is 6.30 × 10^-5.

A)2.516
B)3.892
C)4.502
D)10.158
E)4.195

Question 23

The pH of a solution prepared by dissolving 0.350 mol of solid dimethylamine hydrochloride ((CH₃)₂NH₂Cl)in 1.00 L of 1.10 M dimethylamine ((CH₃)₂NH)is ________. The K_b for methylamine is 5.40 × 10^-4. (Assume the final volume is 1.00 L.)

A)1.66
B)2.77
C)11.23
D)11.14
E)none of the above

Question 24

A result of the common-ion effect is ________.

A)that some ions, such as Na⁺ (aq), frequently appear in solutions but do not participate in solubility equilibria
B)that common ions, such as Na⁺ (aq), don't affect equilibrium constants
C)that the selective precipitation of a metal ion, such as Ag⁺, is promoted by the addition of an appropriate counterion (X^-)that produces a compound (AgX)with a very low solubility
D) that ions such as K⁺ and Na⁺ are common ions, so that their values in equilibrium constant expressions are always 1.00
E)that common ions precipitate all counter-ions

Question 25

Consider the following table of values.
Which compound listed below has the smallest molar solubility in water?

A)ZnCO₃
B)Cd(OH)₂
C)CdCO₃
D)AgI
E)CaF₂

Question 26

Which one of the following will cause hemoglobin to release oxygen?

A)increase in pH
B)decrease in pH
C)decrease in temperature
D)decrease in CO₂ concentration
E)increase in O₂ concentration

Question 27

The pH of a solution prepared by dissolving 0.350 mol of solid methylamine hydrochloride (CH₃NH₃Cl)in 1.00 L of 1.10 M methylamine (CH₃NH₂)is ________. The K_b for methylamine is 4.40 × 10^-4. (Assume the final volume is 1.00 L.)

A)1.66
B)2.86
C)10.28
D)11.14
E)10.61

Question 28

Why does fluoride treatment render teeth more resistant to decay?

A)Fluoride kills the bacteria in the mouth that make the acids that decay teeth.
B)Fluoride stimulates production of tooth enamel to replace that lost to decay.
C)Fluoride reduces saliva production, keeping teeth drier and thus reducing decay.
D)Fluoride converts hydroxyapatite to fluoroapatite that is less reactive with acids.
E)Fluoride dissolves plaque, reducing its decaying contact with teeth.

Question 29

A 25.0 mL sample of a solution of a monoprotic acid is titrated with a 0.115 M NaOH solution. The titration curve above was obtained. Which of the following indicators would be best for this titration?

A)methyl red
B)bromthymol blue
C)thymol blue
D)phenolpthalein
E)bromocresol purple

Question 30

In which one of the following solutions is silver chloride the most soluble?

A)0.181 M HCl
B)0.0176 M NH₃
C)0.744 M LiNO₃
D)pure water
E)0.181 M NaCl

Question 31

Calculate the pH of a solution prepared by dissolving 0.150 mol of acetic acid and 0.300 mol of sodium acetate in water sufficient to yield 1.00 L of solution. The K_a of acetic acid is 1.76 × 10^-5.

A)2.516
B)3.892
C)4.502
D)10.158
E)5.056

Question 32

A 25.0 mL sample of a solution of an unknown compound is titrated with a 0.115 M NaOH solution. The titration curve above was obtained. The unknown compound is ________.

A)a strong acid
B)a strong base
C)a weak acid
D)a weak base
E)neither an acid nor a base

Question 33

Which below best describe(s)the behavior of an amphoteric hydroxide in water?

A)With conc. aq. NaOH, its suspension dissolves.
B)With conc. aq. HCl, its suspension dissolves.
C)With conc. aq. NaOH, its clear solution forms a precipitate.
D)With conc. aq. HCl, its clear solution forms a precipitate.
E)With both conc. aq. NaOH and conc. aq. HCl, its suspension dissolves.

Question 34

Human blood is ________.

A)neutral
B)very basic
C)slightly acidic
D)very acidic
E)slightly basic

Question 35

For which salt should the aqueous solubility be most sensitive to pH?

A)Ca(NO₃)₂
B)CaF₂
C)CaCl₂
D)CaBr₂
E)CaI₂

Question 36

Which one of the following is not amphoteric?

A)Al(OH)₃
B)Ca(OH)₂
C)Cr(OH)₃
D)Zn(OH)₂
E)Sn(OH)₂

Question 37

Consider the following table of values.
Which compound listed below has the greatest molar solubility in water?

A)CdCO₃
B)Cd(OH)₂
C)AgI
D)CaF₂
E)ZnCO₃

Question 38

A 25.0 mL sample of 0.723 M HClO₄ is titrated with a 0.27 M KOH solution. The H₃O⁺ concentration after the addition of 80.0 mL of KOH is ________ M.

A)0.4
B)1 × 10^-7
C)0.7
D)3 × 10^-13
E)4 × 10^-2

Question 39

A 25.0 mL sample of a solution of a monoprotic acid is titrated with a 0.115 M NaOH solution. The titration curve above was obtained. The concentration of the monoprotic acid is about ________ mol/L.

A)25.0
B)0.0600
C)0.240
D)0.120
E)0.100

Question 40

The K_a of benzoic acid is 6.30 × 10^-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M potassium benzoate and 50.0 mL of 1.00 M benzoic acid is ________.

A)1.705
B)0.851
C)3.406
D)4.201
E)2.383

Question 41

Calculate the percent ionization of formic acid (HCO₂H)in a solution that is 0.152 M in formic acid. The K_a of formic acid is 1.77 × 10^-4.

A)2.74 × 10^-5
B)0.0180
C)3.44
D)0.581
E)8.44

Question 42

The pH of a solution prepared by mixing 50.0 mL of 0.125 M NaOH and 40.0 mL of 0.125 M HNO₃ is ________.

A)13.29
B)7.00
C)8.11
D)11.00
E)12.14

Question 43

Calculate the maximum concentration (in M)of silver ions (Ag⁺)in a solution that contains 0.025 M of CO₃^2-. The K_sp of Ag₂CO₃ is 8.1 × 10^-12.

A)1.8 × 10^-5
B)1.4 × 10^-6
C)2.8 × 10^-6
D)3.2 × 10^-10
E)8.1 × 10^-12

Question 44

The concentration of iodide ions in a saturated solution of lead (II)iodide is ________ M. The solubility product constant of PbI₂ is 1.4 × 10^-8.

A)3.8 × 10^-4
B)3.0 × 10^-3
C)1.5 × 10^-3
D)3.5 × 10^-9
E)1.4 × 10^-8

Question 45

Calculate the pH of a solution that is 0.278 M in sodium formate (NaHCO₂)and 0.222 M in formic acid (HCO₂H). The K_a of formic acid is 1.77 × 10^-4.

A)3.843
B)3.647
C)13.90
D)10.16
E)4.954

Question 46

The pH of a solution prepared by mixing 40.0 mL of 0.125 M Mg(OH)₂ and 150.0 mL of 0.125 M HCl is ________.

A)6.29
B)4.11
C)1.14
D)5.78
E)1.34

Question 47

Calculate the maximum concentration (in M)of magnesium ions (Mg⁺²)in a solution that contains 0.025 M of CO₃^2-. The K_sp of MgCO₃ is 3.5 × 10^-8.

A)1.8 × 10^-5
B)1.4 × 10^-6
C)2.8 × 10^-6
D)3.2 × 10^-10
E)8.1 × 10^-12

Question 48

Calculate the percent ionization of formic acid (HCO₂H)in a solution that is 0.322 M in formic acid and 0.178 M in sodium formate (NaHCO₂). The K_a of formic acid is 1.77 × 10^-4.

A)35.6
B)0.1011
C)10.8
D)1.03 × 10^-3
E)3.488

Question 49

What is the solubility (in M)of PbCl₂ in a 0.15 M solution of HCl? The K_sp of PbCl₂ is 1.6 × 10^-5.

A)2.0 × 10^-3
B)1.1 × 10^-4
C)1.8 × 10^-4
D)7.1 × 10^-4
E)1.6 × 10^-5

Question 50

Calculate the pH of a solution that is 0.322 M in nitrous acid (HNO₂)and 0.178 M in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)3.093
B)3.607
C)14.26
D)10.91
E)4.589

Question 51

Calculate the percent ionization of nitrous acid in a solution that is 0.241 M in nitrous acid (HNO₂)and 0.195 M in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)44.7
B)0.229
C)13.5
D)2.11 × 10^-3
E)3.258

Question 52

The K_sp for Zn(OH)₂ is 5.0 × 10^-17. Determine the molar solubility of Zn(OH)₂ in a buffer solution with a pH of 11.5.

A)5.0 × 10⁶
B)1.2 × 10^-12
C)1.6 × 10^-14
D)5.0 × 10^-12
E)5.0 × 10^-17

Question 53

The pH of a solution prepared by mixing 50.0 mL of 0.125 M KOH and 50.0 mL of 0.125 M HCl is ________.

A)6.29
B)7.00
C)8.11
D)5.78
E)0.00

Question 54

Calculate the percent ionization of nitrous acid in a solution that is 0.260 M in nitrous acid. The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)1.17 × 10^-4
B)0.0450
C)4.16
D)0.314
E)5.78

Question 55

The concentration of iodide ions in a saturated solution of silver iodide is ________ M. The solubility product constant of AgI is 8.3 × 10^-17.

A)3.8 × 10^-11
B)3.0 × 10^-10
C)9.1 × 10^-9
D)3.5 × 10^-9
E)1.4 × 10^-8

Question 56

The solubility of manganese (II)hydroxide (Mn(OH)₂)is 2.2 × 10^-5 M. What is the K_sp of Mn(OH)₂?

A)1.1 × 10^-14
B)4.3 × 10^-14
C)2.1 × 10^-14
D)4.8 × 10^-10
E)2.2 × 10^-5

Question 57

The solubility of lead (II)chloride (PbCl₂)is 1.6 × 10^-2 M. What is the K_sp of PbCl₂?

A)5.0 × 10^-4
B)4.1 × 10^-6
C)3.1 × 10^-7
D)1.6 × 10^-5
E)1.6 × 10^-2

Question 58

A 50.0 mL sample of an aqueous H₂SO₄ solution is titrated with a 0.375 M NaOH solution. The equivalence point is reached with 62.5 mL of the base. The concentration of H₂SO₄ is ________ M.

A)0.234
B)0.469
C)0.150
D)0.300
E)0.938

Question 59

Determine the K_sp for magnesium hydroxide (Mg(OH)₂)where the solubility of Mg(OH)₂ is 1.4 × 10^-4 M.

A)2.7 × 10^-12
B)1.1 × 10^-11
C)2.0 × 10^-8
D)3.9 × 10^-8
E)1.4 × 10^-4

Question 60

The concentration of fluoride ions in a saturated solution of barium fluoride is ________ M. The solubility product constant of BaF₂ is 1.7 × 10^-6.

A)3.8 × 10^-4
B)3.0 × 10^-3
C)1.5 × 10^-2
D)7.5 × 10^-3
E)1.4 × 10^-4

Question 61

A buffer solution with a pH of 4.63 is prepared with 0.14 M formic acid and ________ M sodium formate. The K_a of formic acid is 1.8 × 10^-4.

A)1.1
B)2.1
C)5.4 × 10^-6
D)3.0 × 10^-8
E)0.54

Question 62

A buffer solution with a pH of 4.78 is prepared with ________ M formic acid and 0.90 M sodium formate. The K_a of formic acid is 1.8 × 10^-4.

A)0.083
B)0.17
C)3.3 × 10³
D)9.8
E)0.041

Question 63

Calculate the pH of a solution prepared by dissolving 0.850 mol of NH₃ and 0.300 mol of NH₄Cl in water sufficient to yield 1.00 L of solution. The K_b of ammonia is 1.77 × 10^-5.

A)5.204
B)4.300
C)9.700
D)8.781
E)8.796

Question 64

The pH of a solution that contains 0.800 M acetic acid (K_a = 1.76 × 10^-5)and 0.172 M sodium acetate is ________.

A)4.087
B)5.422
C)8.578
D)8.370
E)9.913

Question 65

A solution is prepared by dissolving 0.23 mol of hypochlorous acid and 0.27 mol of sodium hypochlorite in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution. The K_a of hypochlorous acid is 1.36 × 10^-3.

A)H₂O
B)H₃O⁺
C)hypochlorite ion
D)hypochlorous acid
E)This is a buffer solution: the pH does not change upon addition of acid or base.

Question 66

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of fluoride ions after the addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is ________ M.

A)0.0735
B)0.0762
C)0.0980
D)0.0709
E)0.00253

Question 67

A 25.0 mL sample of 0.150 M benzoic acid is titrated with a 0.150 M NaOH solution. What is the pH at the equivalence point? The K_a of benzoic acid is 4.50 × 10^-4.

A)11.20
B)9.80
C)4.20
D)7.00
E)8.54

Question 68

Calculate the pH of a solution prepared by dissolving 0.250 mol of benzoic acid (C₇H₅O₂H)and 0.150 mol of sodium benzoate (NaC₇H₅O₂)in water sufficient to yield 1.00 L of solution. The K_a of benzoic acid is 6.50 × 10^-5.

A)4.409
B)3.965
C)10.035
D)9.591
E)5.190

Question 69

What is the pH of a buffer solution that is 0.172 M in hypochlorous acid (HClO)and 0.131 M in sodium hypochlorite? The K_a of hypochlorous acid is 3.8 × 10^-8.

A)14.12
B)6.70
C)9.07
D)7.54
E)7.30

Question 70

How many milliliters of 0.0839 M NaOH are required to titrate 25.0 mL of 0.0990 M HBr to the equivalence point?

A)29.5
B)0.332
C)4.57
D)0.208
E)21.2

Question 71

Calculate the pH of a solution prepared by dissolving 0.270 mol of formic acid (HCO₂H)and 0.260 mol of sodium formate (NaCO₂H)in water sufficient to yield 1.00 L of solution. The K_a of formic acid is 1.77 × 10^-4.

A)2.099
B)10.264
C)3.736
D)2.307
E)3.952

Question 72

The K_a of acetic acid is 1.76 × 10^-5. The pH of a buffer prepared by combining 15.0 mL of 1.00 M potassium acetate and 50.0 mL of 1.00 M acetic acid is ________.

A)1.705
B)0.851
C)3.406
D)4.232
E)2.383

Question 73

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of hydrogen fluoride after addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is ________ M.

A)0.0953
B)0.0900
C)0.130
D)0.122
E)0.00976

Question 74

Of the following solutions, which has the greatest buffering capacity?

A)1.15 M HF and 0.624 M NaF
B)0.574 M HF and 0.312 M NaF
C)0.287 M HF and 0.156 M NaF
D)0.189 M HF and 0.103 M NaF
E)They are all buffer solutions and would all have the same capacity.

Question 75

A buffer solution with a pH of 4.31 is prepared with 1.0 M HC₂H₃O₂ and ________ M NaC₂H₃O₂. The Ka of HC₂H₃O₂ is 1.8 × 10^-5.

A)0.37
B)0.74
C)4.2 × 10^-6
D)8.8 × 10^-10
E)0.18

Question 76

The K_b of ammonia is 1.76 × 10^-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M ammonia and 45.0 mL of 1.00 M ammonium nitrate is ________.

A)4.632
B)9.291
C)4.742
D)9.372
E)none of the above

Question 77

A buffer solution with a pH of 4.40 is prepared with 0.78 M Na C₂H₃O₂ and ________ M HC₂H₃O₂. The K_a of HC₂H₃O₂ is 1.8 × 10^-5.

A)1.7
B)3.5
C)4.1 × 10⁴
D)0.35
E)0.86

Question 78

The addition of hydrofluoric acid and ________ to water produces a buffer solution.

A)NaF
B)HF
C)NaNO₃
D)NaBr
E)KI

Question 79

A solution is prepared by dissolving 0.23 mol of benzoic acid and 0.27 mol of sodium benzoate in water sufficient to yield 1.00 L of solution.The addition of 0.05 mol of NaOH to this buffer solution causes the pH to increase slightly. The pH does not increase drastically because the NaOH reacts with the ________ present in the buffer solution. The K_a of benzoic acid is 6.3 × 10^-5.

A)H₂O
B)H₃O⁺
C)benzoate
D)benzoic acid
E)This is a buffer solution: the pH does not change upon addition of acid or base.

Question 80

What is the pH of a buffer solution that is 0.266 M in lactic acid and 0.111 M in sodium lactate? The K_a of lactic acid is 1.4 × 10^-4.

A)14.38
B)10.53
C)5.38
D)3.47
E)4.23