Deck 17: Additional Aspects of Equilibria

Question 1

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

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

Answer 1

AgI

Question 2

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

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

Answer 2

0.821 M HF and 0.909 M NaF

Question 3

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

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

Answer 3

carbonic acid, bicarbonate

Question 4

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

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

Question 5

A 25.0- mL sample of 0.150 M butanoic acid is titrated with a 0.150 M NaOH solution. What is the pH before any base is added? The K_a of butanoic acid is 1.5 × 10^{- 5}.

A) 1.0 × 10⁴
B) 1.5 × 10^{- 3}
C) 4.00
D) 2.83
E) 4.82

Question 6

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) 2.78 × 10^{- 3}
B) 55.6
C) 0.161
D) 15.5
E) 3.448

Question 7

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

Question 8

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

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

Question 9

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

Question 10

A solution of NaF is added dropwise to a solution that is 0.0144 M in Ba²⁺. When the concentration of F^- exceeds M, BaF₂ will precipitate. Neglect volume changes. For BaF₂,
K_sp = 1.7 × 10^{- 6}.

A) 1.1 × 10^{- 2}
B) 1.2 × 10^{- 4}
C) 2.4 × 10^{- 8}
D) 2.7 × 10^{- 3}
E) 5.9 × 10^{- 5}

Question 11

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

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

Question 12

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

Question 13

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) 4.963
B) 13.84
C) 10.10
D) 3.903
E) 3.587

Question 14

Why does fluoride treatment render teeth more resistant to decay?

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

Question 15

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

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

Question 16

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

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

Question 17

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

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

Question 18

Human blood is .

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

Question 19

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

Question 20

What is the molar solubility of magnesium carbonate ( MgCO₃ ) in water? The solubility- product constant for MgCO₃ is 3.5 × 10^{- 8} at 25°C.

A) 7.0 × 10^{- 8}
B) 1.8 × 10^{- 8}
C) 1.9 × 10^{- 4}
D) 7.46
E) 2.6 × 10^{- 4}

Question 21

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

Question 22

A solution is prepared by dissolving 0.23 mol of chloroacetic acid and 0.27 mol of sodium chloroacetate 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 chloroacetic acid is 1.36 × 10^{- 3}.

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

Question 23

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

A) Na₃PO₄
B) AlCl₃
C) NaF
D) KNO₃
E) MnS

Question 24

A 25.0 mL sample of 0.150 M hypochlorous acid is titrated with a 0.150 M NaOH solution. What is the pH after 26.0 mL of base is added? The K_a of hypochlorous acid is 3.0 × 10^{- 8}.

A) 11.47
B) 2.54
C) 7.54
D) 7.51
E) 7.00

Question 25

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

A) NaNO₃
B) NaCl
C) NaF
D) HCl
E) NaBr

Question 26

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

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

Question 27

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 1.37 × 10^{- 4}.

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

Question 28

How many milliliters of 0.120 M NaOH are required to titrate 50.0 mL of 0.0998 M butanoic acid to the equivalence point? The K_a of butanoic acid is 1.5 × 10^{- 5}.

A) 4.90
B) 41.6
C) 50.0
D) 4.65
E) 60.1

Question 29

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

A) 3.35
B) 7.00
C) 8.11
D) 10.35
E) 10.65

Question 30

How many milliliters of 0.0850 M NaOH are required to titrate 25.0 mL of 0.0720 M HBr to the equivalence point?

A) 3.92
B) 21.2
C) 0.245
D) 0.153
E) 29.5

Question 31

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

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

Question 32

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

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

Question 33

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

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

Question 34

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

Question 35

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

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

Question 36

In which aqueous system is PbI₂ least soluble?

A) 0.5 M HI
B) 1.0 M HNO₃
C) 0.2 M HI
D) 0.8 M KI
E) H₂O

Question 37

A 25.0- mL sample of 0.150 M hydrazoic acid is titrated with a 0.150 M NaOH solution. What is the pH after 13.3 mL of base is added? The K_a of hydrazoic acid is 1.9 × 10^{- 5}.

A) 4.66
B) 4.78
C) 3.03
D) 1.34
E) 4.45

Question 38

A solution of HF is titrated with a 0.150 M NaOH solution. Based on the table above, the best indicator for this reaction is . The K_a of hydrofluoric acid is 6.8 × 10^{- 4}.

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

Question 39

Which one of the following is not amphoteric?

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

Question 40

The pH of a solution prepared by mixing 45 mL of 0.183 M KOH and 65 mL of 0.145 M HCl is
)

A) 70.145
B) 2.92
C) 0.74
D) 1.31
E) 1.97

Question 41

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) 0.0952
B) 1.06 × 10^{- 3}
C) 11.3
D) 3.529
E) 37.8

Question 42

The common- ion effect refers to the observation _ .

A) ions such as K⁺ and Na⁺ are common ions, so that their values in equilibrium constant expressions are always 1.00
B) 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
C) that some ions, such as Na⁺ (aq), frequently appear in solutions but do not participate in solubility equilibria
D) common ions, such as Na⁺ (aq), don't affect equilibrium constants
E) that common ions precipitate all counter- ions

Question 43

Suppose you have just added 200.0 ml of a solution containing 0.5000 moles of acetic acid per liter to 100.0 ml of 0.5000 M NaOH. What is the final pH? The Ka of acetic acid is 1.770× 10^{- 5}.

Question 44

Calculate the pH of a buffer that contains 0.270 M hydrofluoric acid (HF) and 0.180 M cesium fluoride (CsF). The Ka of hydrofluoric acid is 6.80 × 10^{- 4}.

Question 45

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

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

Question 46

Which of the following could be added to a solution of acetic acid to prepare a buffer? sodium acetate sodium hydroxide nitric acid hydrofluoric acid

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

Question 47

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

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

Question 48

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) 4.562
B) 3.490
C) 13.86
D) 10.51
E) 3.210

Question 49

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

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

Question 50

A 25.0 mL sample of 0.723 M HClO₄ is titrated with a 0.273 M KOH solution. The H₃O⁺ concentration after the addition of 10.0 mL of KOH is M.

A) 1.00 × 10^{- 7}
B) 0.273
C) 0.723
D) 0.440
E) 2.81 × 10^{- 13}

Question 51

What is the molar solubility of barium fluoride ( BaF₂ ) in water? The solubility- product constant for BaF₂ is 1.7 × 10^{- 6} at 25°C.

A) 1.2 × 10^{- 2}
B) 1.8 × 10^{- 3}
C) 5.7 × 10^{- 7}
D) 6.5 × 10^{- 4}
E) 7.5 × 10^{- 3}

Question 52

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

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

Question 53

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

A) 0.85
B) 2.38
C) 4.77
D) 1.70
E) 3.40

Question 54

Suppose you have just added 100.0 ml of a solution containing 0.5000 moles of acetic acid per liter to 400.0 ml of 0.5000 M NaOH. What is the final pH? The Ka of acetic acid is 1.770× 10^{- 5}.

Question 55

200.0 ml of a solution containing 0.5000 moles of acetic acid per liter is added to 200.0 ml of 0.5000 M NaOH. What is the final pH? The Ka of acetic acid is 1.770 × 10^{- 5}.

Question 56

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) 12.2
B) 3.94 × 10^{- 5}
C) 0.280
D) 0.0180
E) 2.87

Question 57

Calculate the pH of a buffer solution that contains 0.820 grams of sodium acetate and 0.01 moles of acetic acid in 100 ml of water. The Ka of acetic acid is 1.77 × 10^{- 5}.

Question 58

Which of the following could be added to a solution of sodium acetate to produce a buffer? acetic acid hydrochloric acid potassium acetate sodium chloride

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

Question 59

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

Question 60

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 3.81 × 10^{- 8}.

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

Question 61

Calculate the pH of a solution prepared by dissolving 0.750 mol of NH₃ and 0.250 mol of NH₄Cl in water sufficient to yield 1.00 L of solution. The K_b of ammonia is 1.77 × 10^{- 4}.

A) 8.78
B) 0.89
C) 9.73
D) 4.27
E) 5.22

Question 62

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

Question 63

The pH of a solution that contains 0.818 M acetic acid (K_a = 1.76 × 10^{- 5}) and 0.172 M sodium acetate is _.

A) 8.57
B) 9.92
C) 4.08
D) 5.43
E) 8.37

Question 64

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

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

Question 65

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of hydrogen fluoride after addition of 5.00 mL of 0.0100 M HCl to 25.0 mL of this solution is __ M.

A) 0.00976
B) 0.00193
C) 0.100
D) 0.126
E) 0.107

Question 66

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

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

Question 67

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}. 78)

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

Question 68

The K_b of ammonia is 1.77 × 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) 7.00
B) 9.25
C) 9.37
D) 4.74
E) 4.63

Question 69

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}.

A) 2.86
B) 1.66
C) 11.1
D) 10.6
E) 10.2

Question 70

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

Question 71

A 25.0 mL sample of an HCl solution is titrated with a 0.139 M NaOH solution. The equivalence point is reached with 15.4 mL of base. The concentration of HCl is M.

A) 0.267
B) 0.0856
C) 0.00214
D) 0.139
E) 11.7

Question 72

Calculate the pH of a solution prepared by dissolving 0.150 mol of benzoic acid (HBz) and
0)300 mol of sodium benzoate in water sufficient to yield 1.00 L of solution. The K_a of benzoic acid is 6.50 × 10^{- 5}.

A) 2.51
B) 4.19
C) 4.49
D) 3.89
E) 10.1

Question 73

Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The concentration of fluoride ions after the addition of 5.00 mL of 0.0100 M HCl to 25.0 mL of this solution is __ M.

A) 0.00167
B) 0.00253
C) 0.0817
D) 0.0980
E) 0.0850

Question 74

A 25.0 mL sample of 0.723 M HClO₄ is titrated with a 0.273 M KOH solution. The H₃O⁺ concentration after the addition of 66.2 mL of KOH is M.

A) 0.439
B) 2.81 × 10^{- 13}
C) 0.273
D) 0.723
E) 1.00 × 10^{- 7}

Question 75

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

Question 76

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

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

Question 77

A 25.0 mL sample of 0.723 M HClO₄ is titrated with a 0.273 M KOH solution. What is the [H⁺] (molarity) before any base is added?

A) 0.439
B) 1.00 × 10^{- 7}
C) 0.723
D) 0.273
E) 2.81 × 10^{- 13}

Question 78

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) 1.0 × 10^{- 7}
B) 0.44
C) 2.8 × 10^{- 13}
D) 0.72
E) 3.6 × 10^{- 2}

Question 79

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

Question 80

Calculate the pH of a solution prepared by dissolving 0.370 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) 3.54
B) 10.46
C) 2.09
D) 3.95
E) 2.30