Chemistry: The Central Science, 12e (Brown et al.)
Chapter 17 Additional Aspects of Aqueous Equilibria
17.1 Multiple–Choice Questions
1) 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
2) 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
3) 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
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
5) 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
6) 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.
7) The Henderson-Hasselbalch equation is __________.
A) [H+] = Ka +
base
acid
B) pH = pKa – log
base
acid
C) pH = pKa + log
base
acid
D) pH = pKa + log
acid
base
E) pH = log
acid
base
8) 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 Ka are equal.
D) all of the above are true.
9) 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.
10) 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
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.
12) The addition of hydrofluoric acid and __________ to water produces a buffer solution.
A) HCl
B) NaNO3
C) NaF
D) NaCl
E) NaBr
13) The addition of hydrofluoric acid and __________ to water produces a buffer solution.
A) HCl
B) NaNO3
C) NaCl
D) NaOH
E) NaBr
14) The addition of hydrochloric acid and __________ to water produces a buffer solution.
A) HC6H5O
B) NaOH
C) NH3
D) HNO3
E) NaNO3
15) 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
16) 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
17) 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
18) 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
19) 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.
20) 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
21) 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
22) 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
23) Human blood is __________.
A) neutral
B) very basic
C) slightly acidic
D) very acidic
E) slightly basic
24) 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
25) 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
26) 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
27) 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
Consider the following table of Ksp values.
28) Which compound listed below has the greatest molar solubility in water?
A) CdCO3
B) Cd(OH)2
C) AgI
D) CaF2
E) ZnCO3
29) Which compound listed below has the smallest molar solubility in water?
A) ZnCO3
B) Cd(OH)2
C) CdCO3
D) AgI
E) CaF2
30) The molar solubility of __________ is not affected by the pH of the solution.
A) Na3PO4
B) NaF
C) KNO3
D) ACl3
E) MnS
31) 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
32) 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
33) 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
34) 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
35) 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
36) 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
37) 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
38) 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
39) For which salt should the aqueous solubility be most sensitive to pH?
A) Ca(NO3)2
B) CaF2
C) CaCl2
D) CaBr2
E) CaI2
40) 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.
41) 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
42) 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.
43) 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
17.2 Bimodal Questions
1) The Ka 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
2) 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 Ka of benzoic acid is 6.30 × 10-5.
A) 2.516
B) 3.892
C) 4.502
D) 10.158
E) 4.195
3) 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 Ka of acetic acid is 1.76 × 10-5.
A) 2.516
B) 3.892
C) 4.502
D) 10.158
E) 5.056
4) 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 Kb 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
5) 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 Kb 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
6) 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
7) 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
8) 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
9) 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
10) 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
11) 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