Deck 17: Additional Aspects of Aqueous Equilibria

Question 1

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

A)HC₆H₅O
B)NaOH
C)NH₃
D)HNO₃
E)NaNO₃

Answer 1

NH₃

Question 2

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.

Answer 2

the -log of the [H⁺] and the -log of the K_a are equal.

Question 3

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.

Answer 3

The concentration of fluoride ion will decrease and the concentration of hydrogen fluoride will increase.

Question 4

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 5

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

A)HCl
B)NaNO₃
C)NaF
D)NaCl
E)NaBr

Question 6

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 7

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 8

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 9

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 10

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

A)HCl
B)NaNO₃
C)NaCl
D)NaOH
E)NaBr

Question 11

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.

Question 12

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 13

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 14

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

A)0.821 M HF and 0.217 M NaF
B)0.821 M HF and 0.909 M NaF
C)0.100 M HF and 0.217 M NaF
D)0.121 M HF and 0.667 M NaF
E)They are all buffer solutions and would all have the same capacity.

Question 15

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 16

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

Question 17

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

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

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 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

In which of the following aqueous solutions would you expect PbCl₂to have the lowest solubility?

A)0.020 M KCl
B)0.020 M BaCl₂
C)0.015 M PbNO₃
D)pure water
E)0.015 M NaCl

Question 22

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 23

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 24

In which of the following aqueous solutions would you expect CuBr to have the highest solubility?

A)pure water
B)0.10 M AgNO₃
C)0.20 M NaBr
D)0.15 M KBr
E)0.10 M LiBr

Question 25

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 26

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 27

Which compound listed below has the smallest molar solubility in water?

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

Question 28

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

A)Na₃PO₄
B)NaF
C)KNO₃
D)ACl₃
E)MnS

Question 29

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 30

In which of the following aqueous solutions would you expect AgCl to have the highest solubility?

A)pure water
B)0.020 M BaCl₂
C)0.015 NaCl
D)0.020 AgNO₃
E)0.020 KCl

Question 31

In which of the following aqueous solutions would you expect AgBr to have the lowest solubility?

A)pure water
B)0.20 M NaBr
C)0.10 M AgNO₃
D)0.15 M KBr
E)0.10 M LiBr

Question 32

Human blood is __________.

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

Question 33

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 34

Which compound listed below has the greatest molar solubility in water?

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

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

In which of the following aqueous solutions would you expect AgCl to have the lowest solubility?

A)pure water
B)0.020 M BaCl₂
C)0.015 NaCl
D)0.020 AgNO₃
E)0.020 KCl

Question 37

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 38

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 39

In which of the following aqueous solutions would you expect AgBr to have the highest solubility?

A)0.10 M LiBr
B)0.10 M AgNO₃
C)0.20 M NaBr
D)0.15 M KBr
E)pure water

Question 40

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 41

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 42

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 43

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 44

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)none of the above

Question 45

The solubility of manganese (II)hydroxide (Mn(OH)₂)is 2.2 × 10^-5 M. What is the K_sp of MnOH)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 46

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 47

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 48

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 49

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 50

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 51

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 52

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 53

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 54

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 55

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 56

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 57

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 58

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 59

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 60

Of the substances below, __________ will decrease the solubility of Pb(OH)₂ in a saturated solution.

A)NaNO₃
B)H₂O₂
C)HNO₃
D)Pb(NO₃)₂
E)NaCl

Question 61

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of hydrogen fluoride after addition of 8.00 mL of 0.0100 M HCl to 25.0 mL of this solution is __________ M.

A)0.0979
B)0.0930
C)0.129
D)0.123
E)0.00976

Question 62

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 63

A solution is prepared by dissolving 0.23 mol of hydrazoic acid and 0.27 mol of sodium azide 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 hydrazoic acid is 1.9 × 10^-5.

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

Question 64

What is the pH of a buffer solution that is 0.211 M in lactic acid and 0.111 M in sodium lactate? The K_a of lactic acid is 1.4 × 10^-4.

A)14.28
B)10.43
C)5.48
D)3.57
E)4.13

Question 65

Calculate the pH of a solution prepared by dissolving 0.850 mol of NH₃ and 0.350 mol of NH₄Cl in water sufficient to yield 1.00 L of solution. The K_b of ammonia is 1.77 × 10^-5.

A)5.137
B)4.367
C)9.633
D)8.781
E)8.863

Question 66

Calculate the percent ionization of nitrous acid in a solution that is 0.222 M in nitrous acid (HNO₂)and 0.278 M in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)55.6
B)0.162
C)15.5
D)2.78 × 10^-3
E)3.448

Question 67

Calculate the percent ionization of nitrous acid in a solution that is 0.249 M in nitrous acid. The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)1.12 × 10^-4
B)0.0450
C)4.25
D)0.342
E)5.53

Question 68

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 50.0 mL of 1.00 M ammonium nitrate is __________.

A)4.632
B)9.246
C)4.742
D)9.372
E)none of the above

Question 69

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of fluoride ions after the addition of 4.00 mL of 0.0100 M HCl to 25.0 mL of this solution is __________ M.

A)0.0862
B)0.0876
C)0.0980
D)0.0848
E)0.00253

Question 70

What is the pH of a buffer solution that is 0.255 M in hypochlorous acid (HClO)and 0.333 M in sodium hypochlorite? The K_a of hypochlorous acid is 3.8 × 10^-8.

A)13.88
B)6.46
C)8.49
D)7.30
E)7.54

Question 71

Calculate the pH of a solution that is 0.295 M in sodium formate (NaHCO₂)and 0.205 M in formic acid (HCO₂H). The K_a of formic acid is 1.77 × 10^-4.

A)3.910
B)3.587
C)13.84
D)10.10
E)4.963

Question 72

Calculate the percent ionization of formic acid (HCO₂H)in a solution that is 0.311 M in formic acid and 0.189 M in sodium formate (NaHCO₂). The K_a of formic acid is 1.77 × 10^-4.

A)37.8
B)0.0937
C)11.3
D)1.06 × 10^-3
E)3.529

Question 73

A solution is prepared by dissolving 0.23 mol of hydrofluoric acid and 0.27 mol of sodium fluoride 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 hydrofluoric acid is 1.36 × 10^-3.

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

Question 74

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 75

The K_a of acetic acid is 1.76 × 10^-5. The pH of a buffer prepared by combining 45.0 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)4.709
E)2.383

Question 76

Calculate the pH of a solution prepared by dissolving 0.270 mol of formic acid (HCO₂H)and 0.230 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)10.318
C)3.682
D)2.307
E)3.952

Question 77

Calculate the pH of a solution that is 0.210 M in nitrous acid (HNO₂)and 0.290 M in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A)3.487
B)3.210
C)13.86
D)10.51
E)4.562

Question 78

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 79

Calculate the percent ionization of formic acid (HCO₂H)in a solution that is 0.219 M in formic acid. The K_a of formic acid is 1.77 × 10^-4.

A)3.94 × 10^-5
B)0.0180
C)2.84
D)0.280
E)12.2

Question 80

The pH of a solution that contains 0.818 M acetic acid (K_a = 1.76 × 10^-5)and 0.182 M sodium acetate is __________.

A)4.102
B)5.407
C)8.593
D)8.370
E)9.898