Deck 17: Additional Aspects of Aqueous Equilibria

Question 1

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

A)HBr
B)NaOH
C)LiC₂H₃O₂
D)KF
E)NH₃

Answer 1

HBr

Question 2

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

Answer 2

acetic acid or hydrochloric acid

Question 3

Which of the following could be added to a solution of HC₂H₃O₂ to prepare a buffer?

A)HBr
B)HNO₃
C)KOH
D)more HC₂H₃O₂
E)None of the above can be added to an acetic acid solution to prepare a buffer.

Answer 3

KOH

Question 4

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 5

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

A)HC₆H₅O
B)C₂H₅NH₂
C)KOH
D)KCl
E)none of the above

Question 6

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 7

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 8

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 9

Which solution has the greatest buffering capacity?

A)0.335M HC₂H₃O₂ and 0.497 M NaC₂H₃O₂
B)0.520 M HC₂H₃O₂ and 0.116 M NaC₂H₃O₂
C)0.820 M HC₂H₃O₂ and 0.715 M NaC₂H₃O₂
D)0.120 M HC₂H₃O₂ and 0.115 M NaC₂H₃O₂

Question 10

What is the primary buffer system that controls the pH of the blood?

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

Question 11

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 12

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

A)NH₃
B)HC₆H₅O
C)KOH
D)KNO₃
E)HNO₃

Question 13

Which solution has the greatest buffering capacity?

A)0.335 M NH₃ and 0.100 M NH₄Cl
B)0.085 M NH₃ and 0.090 M NH₄Cl
C)0.540 M NH₃ and 0.550 M NH₄Cl
D)0.200 M NH₃ and 0.565 M NH₄Cl
E)They are all buffer solutions and would all have the same capacity.

Question 14

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 15

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 16

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

A)HBr
B)KNO₃
C)KOH
D)NaCl
E)NaBr

Question 17

The ________ and ________ are the principal organs that regulate the pH of the carbonic acid-bicarbonate buffer system in the blood.

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

Question 18

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 19

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

A)HI
B)NH₃
C)KF
D)LiC₂H₃O₂
E)none of the above

Question 20

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 21

The pH of a solution prepared by dissolving 0.550 mol of solid methylamine hydrochloride (CH₃NH₃Cl)in of methylamine (CH₃NH₂)is ________.The K_b for methylamine is (Assume the final volume is 1.00 L.)

A)11.03
B)2.97
C)3.75
D)10.64
E)10.25

Question 22

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

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

Question 23

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 24

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

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

Question 25

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 26

Human blood is considered to be ________.

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

Question 27

The K_a of benzoic acid is 6.30 × 10^-5.The pH of a buffer prepared by combining 50.0 mL of 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 28

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

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

Question 29

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 30

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

A)MgCl₂
B)Mg(NO₃)₂
C)MgF₂
D)MgBr₂
E)MgI₂

Question 31

Which one of the following is amphoteric?

A)H₂SO₄
B)H₂O₂
C)CO₂
D)H₂O
E)NaOH

Question 32

A 50.0 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)0.120
B)25.0
C)0.240
D)0.0600
E)0.100

Question 33

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

A)Na₃PO₄
B)NaF
C)KNO₃
D)AlCl₃
E)MnS

Question 34

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 35

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 36

Calculate the pH of a solution prepared by dissolving of benzoic acid and of sodium benzoate in water sufficient to yield of solution.The K_a of benzoic acid is

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

Question 37

Calculate the pH of a solution prepared by dissolving of acetic acid and of sodium acetate in water sufficient to yield of solution.The K_a of acetic acid is

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

Question 38

The pH of a solution prepared by dissolving 0.350 mol of acid in of of conjugate base is ________.The K_b for the conjugate base is (Assume the final volume is 1.00 L.)

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

Question 39

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

A)0.200 M HCl
B)0.750 M LiNO₃
C)0.0150 M NH₃
D)0.185 M KCl
E)pure H₂O

Question 40

Decreasing the pH of blood will cause hemoglobin to release ________.

A)CO₂
B)N₂
C)H₂
D)O₂
E)Fe

Question 41

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 42

The K_sp for Cu(OH)₂ is 4.8 × 10^-20.Determine the molar solubility of Cu(OH)₂ in a buffer solution with a pH of 10.1.

A)6.0 × 10^-10
B)7.6
C)3.0 × 10^-12
D)2.2 × 10^-10
E)3.8 × 10^-16

Question 43

The solubility of lead (II)chloride (PbCl₂)is 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 44

What is the solubility (in M)of PbCl₂ in a solution of HCl? The K_sp of PbCl₂ is

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 45

The concentration of iodide ions in a saturated solution of silver iodide is ________ M.The solubility product constant of AgI is

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 46

Calculate the pH of a solution that is 0.278 M in sodium formate ( )and in formic acid The of formic acid is 1.77 × .

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

Question 47

The concentration of iodide ions in a saturated solution of lead (II)iodide is ________ M.The solubility product constant of PbI₂ is

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 48

Calculate the percent ionization of formic acid ( H)in a solution that is 0.322 M in formic acid and 0.178 M in sodium formate ( ).The of formic acid is 1.77 × .

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

Question 49

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

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 50

What is 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

A)55.6
B)15.5
C)2.78 ×
D)3.448
E)0.162

Question 51

A 50.0 mL sample of an aqueous H₂SO₄ solution is titrated with a NaOH solution.The equivalence point is reached with 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

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 53

The concentration of fluoride ions in a saturated solution of barium fluoride is ________ M.The solubility product constant of BaF₂ is

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 54

What is the percent ionization of nitrous acid in a solution that is 0.189 M in nitrous acid? The acid dissociation constant of nitrous acid is

A)0.0450
B)8.51 × 10^-5
C)0.594
D)4.20
E)4.88

Question 55

Calculate the percent ionization of formic acid ( H)in a solution that is 0.152 M in formic acid.The of formic acid is 1.77 × .

A)2.74 ×
B)0.0180
C)3.44
D)0.581
E)8.44

Question 56

The solubility of manganese (II)hydroxide (Mn(OH)₂)is 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 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 58

Determine the K_sp for magnesium hydroxide (Mg(OH)₂)where the solubility of Mg(OH)₂ is .

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 59

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

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

Question 60

Calculate the maximum concentration (in M)of calcium ions (Ca²⁺)in a solution that contains of CO₃^2-.The K_sp of CaCO₃ is

A)5.8 × 10^-5
B)6.8 × 10^-9
C)3.4 × 10^-9
D)6.2 × 10^-8
E)1.9 × 10^-10

Question 61

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

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

Question 62

Which solution would have the greatest buffering capacity?

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

Question 63

The of some weak acid HA is 1.76 × .The pH of a buffer prepared by combining 15.0 mL of A^- and 50.0 mL of 1.00 M HA is ________.

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

Question 64

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 of hypochlorous acid is 1.36 × 10^-3.

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

Question 65

The of ammonia is 1.76 × .What is the pH of a buffer which is prepared by combining 50.0 mL of 1.00 M ammonia and 45.0 mL of 1.00 M ammonium nitrate?

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

Question 66

A buffer solution with a pH of 4.31 is prepared with and The Ka of H is

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

Question 67

0.78 M Na and are required to prepare a buffer solution with a pH of 4.40 .The of H is

A)3.5
B)4.1 × 10⁴
C)1.7
D)0.86
E)0.35

Question 68

What is the pH of a solution which is prepared by dissolving 0.850 mol of N and of in water sufficient to yield 1.00 L of solution? The of ammonia is

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

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 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 70

A buffer solution contains 0.100 M fluoride ions and 0.126 M hydrogen fluoride.What is the concentration (M)of hydrogen fluoride after addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution?

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

Question 71

Calculate the pH of a solution prepared by dissolving 0.270 mol of weak acid HA and 0.260 mol of its conjugate base in water sufficient to yield 1.00 L of solution.The of HA is

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

Question 72

acid and formate are required to prepare a buffer solution with a pH of 4.78 .The of formic acid is

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

Question 73

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

A)11.74
B)9.26
C)4.74
D)7.00
E)8.81

Question 74

What is the pH of a solution that contains 0.800 M weak acid ( = 1.76 × )and 0.172 M of its conjugate base?

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

Question 75

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

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

Question 76

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

A)NaF
B)HF
C)NaN
D)NaBr
E)KI

Question 77

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 of benzoic acid is 6.3 × 10^-5.

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

Question 78

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 of hypochlorous acid is 3.8 × .

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

Question 79

Calculate the pH of a solution prepared by dissolving 0.250 mol of benzoic acid ( H)and of sodium benzoate (Na )in water sufficient to yield 1.00 L of solution.The of benzoic acid is

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

Question 80

A buffer solution with a pH of 4.63 is prepared with acid and formate. The of formic acid is

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