Chapter 14

Chemistry, 6e (McMurry/Fay)Chapter 14 Aqueous Equilibria: Acids and Bases

14.1 Multiple-Choice Questions

1) An Arrhenius acid is best defined as aA) hydroxide donor.B) proton acceptor.C) substance that dissociates in water to produce aqueous hydrogen ions.D) substance that dissociates in water to produce aqueous hydroxide ions.Answer: CTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

2) When dissolved in water, which of the following compounds is an Arrhenius acid?A) HCNB) NaOHC) NaFD) CH3CH2OHAnswer: ATopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

3) An Arrhenius base is best defined as aA) proton donor.B) hydroxide acceptor.C) substance that dissociates in water to produce aqueous hydrogen ions.D) substance that dissociates in water to produce aqueous hydroxide ions.Answer: DTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

4) When dissolved in water, which of the following compounds is an Arrhenius base?A) CH3OHB) HOClC) KOHD) KClAnswer: CTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

5) A Br∅nsted-Lowry acid is best defined as a substance that canA) accept a hydroxide ion.B) donate a hydroxide ion.C) accept a proton.D) donate a proton.Answer: DTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

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6) Which one of the following species acts as a Br∅nsted-Lowry acid in water?A) NaHB) NH4+

C) CH3NH2D) C6H6Answer: BTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

7) In the following chemical equation indicate the reactant that is a Br∅nsted-Lowry acid.HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq)

A) HCNB) H2O

C) H3O+

D) CN-Answer: ATopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

8) Indicate all the Br∅nsted-Lowry acids in the following chemical reaction.HCl(aq) + H2O(aq) ⇌ H3O+(aq) + Cl-(aq)

A) HCl, H2O

B) HCl, H3O+

C) HCl, Cl-

D) HCl, H2O, H3O+

Answer: BTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

9) What are the Br∅nsted-Lowry bases in the following chemical reaction?C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq)

A) C5H5N, H2O

B) C5H5N, C5H5NH+

C) C5H5N, OH-

D) C5H5N, H2O, OH-

Answer: CTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

10) What are the Br∅nsted-Lowry acids in the following chemical reaction?HBr(sol) + CH3COOH(sol) ⇌ CH3C(OH)2+(sol) + Br-(sol)

A) HBr, CH3COOH

B) HBr, CH3C(OH)2+

C) CH3COOH, CH3C(OH)2+

D) CH3COOH, Br-



11) What are the conjugate acid-base pairs in the following chemical reaction?NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

A) NH3, H2O and NH4+, OH-

B) NH3, NH4+ and H2O, OH-

C) NH3, OH- and H2O, NH4+

D) NH3 and NH4+


12) Identify the conjugate acid/base pairs present in an aqueous solution of hydrogen sulfate ion, HSO4-.

A) HSO4-/SO42- and H3O+/H2O

B) H2SO4/HSO4- and H2O/OH-

C) HSO4-/H2O and H3O+/SO42-

D) HSO4-/H2O and H2SO4/OH-

Answer: ATopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

13) What is the conjugate base of the Br∅nsted-Lowry acid HPO42-?A) H3PO4B) H2PO4-

C) HPO42-

D) PO43-

Answer: DTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

14) What is the conjugate acid of the Br∅nsted-Lowry base HAsO42-?

A) H2AsO4-

B) AsO43-

C) H2O

D) H3O+

Answer: ATopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

15) Which one of the following can behave either as a Br∅nsted-Lowry acid or a Br∅nsted-Lowry base in an aqueous solution reaction?A) HSO3-

B) NH3C) HID) H3PO4Answer: A


Topic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

16) Write a balanced equation for the dissociation of the Br∅nsted-Lowry acid HSO4- in water.

A) HSO4-(aq) + H2O(l) ⇌ H2SO4(aq) + OH-(aq)

B) HSO4-(aq) + H2O(l) ⇌ SO42-(aq) + H3O+(aq)

C) HSO4-(aq) + H2O(l) ⇌ SO32-(aq) + OH-(aq)

D) HSO4-(aq) + H2O(l) ⇌ SO3(g) + OH-(aq) + H2O(l)Answer: BTopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

17) Which of the following Br∅nsted-Lowry acids does not behave as a strong acid when it is dissolved in water?A) HBrB) HClC) HNO2D) HClO4Answer: CTopic: Section 14.2 Acid Strength and Base Strength

18) Which Br∅nsted-Lowry base has the strongest conjugate acid?A) CH3CO2-

B) CN-

C) F-

D) NO3-

Answer: DTopic: Section 14.2 Acid Strength and Base Strength

19) Which Br∅nsted-Lowry acid has the strongest conjugate base?A) HBrB) HClO4C) HFD) HIAnswer: CTopic: Section 14.2 Acid Strength and Base Strength

20) What is the strongest Br∅nsted-Lowry acid in the chemical reaction shown below?2 HNO3(aq) + Ba(OH)2(aq) → Ba(NO3)2(aq) + 2 H2O(l)

A) HNO3B) Ba(OH)2C) Ba(NO3)2D) H2OAnswer: ATopic: Section 14.2 Acid Strength and Base Strength


21) From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths (strongest to weakest).

HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq)

HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq)

A) HCl > HCN > H3O+

B) HCl > H3O+ > HCN

C) H3O+ > HCl > HCN

D) HCN > H3O+ > HClAnswer: BTopic: Section 14.2 Acid Strength and Base Strength


HClO4(aq) + H2O(l) → H3O+(aq) + ClO4-(aq)

HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq)

A) HClO4 > H3O+ > HNO2B) HClO4 > HNO2 > H3O+

C) H3O+ > HClO4 > HNO2D) H3O+ > HNO2 > HClO4Answer: ATopic: Section 14.2 Acid Strength and Base Strength


HClO4(sol) + CH3COOH(l) → CH3C2(OH)2+(sol) + ClO4-(aq)

H2SO4(sol) + CH3COOH(l) ⇌ CH3C(OH)2+(sol) + HSO4-(sol)A) HClO4 > H2SO4 > CH3COOH

B) HClO4 > H2SO4 > CH3C(OH)2+

C) HClO4 > CH3COOH > H2SO4D) HClO4 > CH3C(OH)2+ > H2SO4Answer: DTopic: Section 14.2 Acid Strength and Base Strength


24) From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths (strongest to weakest).

HNO3(aq) + H2O(l) → H3O+(aq) + NO3-(aq)

HF(aq) + H2O(l) ⇌ H3O+(aq) + F-(aq)

A) HNO3 > H3O+ > HF

B) NO3- > H2O > F-

C) F- > H2O > NO3-

D) F- > NO3- > H2OAnswer: CTopic: Section 14.2 Acid Strength and Base Strength

25) From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths (strongest to weakest).

2 NaH(s) + H2O(l) → 2 NaOH + H2(g)

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq)

A) H- > OH- > NH3B) H- > NH3 > OH-

C) OH-> H- > NH3D) OH- > NH3 > H-

Answer: ATopic: Section 14.2 Acid Strength and Base Strength

26) The equilibrium constant, K, for the reaction shown below has a value 1.8 × 10–5. In this reaction which is the strongest acid and which is the strongest base?

CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2–(aq)

A) CH3CO2H and CH3CO2– B) CH3CO2H and H2O

C) H3O+ and H2O

D) H3O+ and CH3CO2–



The following pictures represent aqueous solutions of binary acids of the type HA where the water molecules have been omitted for clarity.

27) Determine the strongest acid of the set.A) AB) BC) CD) DAnswer: BTopic: Section 14.2 Acid Strength and Base Strength

28) Arrange the acids in order of increasing acid strength.A) D < C < A < BB) D < C < B < AC) D < B < A < CD) D < A < C < BAnswer: DTopic: Section 14.2 Acid Strength and Base Strength

29) Using the conjugate acid-base pairs listed below, complete the following equation with the pair that gives an equilibrium constant Kc > 1.

_____ + HSO3- ⇌ _____ + H2SO3A) CH3CO2H/ CH3CO2-

B) HCO2H/ HCO2-

C) HNO2/NO2-

D) HNO3/NO3-



30) Using the conjugate acid-base pairs listed below, complete the following equation with the pair that gives an equilibrium constant Kc > 1.

_____ + H2CO3 ⇌ _____ + HCO3-

A) HF/F-

B) HCl/Cl-

C) HOCl/OCl-

D) HSO42-/SO42-

Answer: CTopic: Section 14.2 Acid Strength and Base Strength

31) What is the geometric shape of the hydrated proton; that is, the hydronium ion H3O+?A) angularB) pyramidalC) trigonal planarD) tetrahedralAnswer: BTopic: Section 14.3 Hydrated Protons and Hydronium Ions

32) Which is not a hydrate of a proton?A) H3O+

B) H9O4+

C) H25O11+

D) H43O21+

Answer: CTopic: Section 14.3 Hydrated Protons and Hydronium Ions

33) An acidic solution at 25°C hasA) [H3O+] > [OH-] > 1 × 10-7 M.

B) [H3O+] > 1 × 10-7 M > [OH-].

C) [H3O+] = [OH-] > 1 × 10-7 M.

D) [H3O+] < 1 × 10-7 M > [OH-].Answer: BTopic: Section 14.4 Dissociation of Water

34) At 50°C the value of Kw is 5.5 × 10-14. A basic solution at 50°C has

A) [H3O+] < [OH-] < 2 × 10-7 M.

B) [H3O+] < 2 × 10-7 M < [OH-].

C) [H3O+] = [OH-] < 2 × 10-7 M.

D) [H3O+] > 2 × 10-7 M < [OH-].Answer: BTopic: Section 14.4 Dissociation of Water


35) Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10-4 M in hydroxide ion.A) 4.00 × 10-9 MB) 4.00 × 10-10 MC) 4.00 × 10-11 MD) 5.00 × 10-11 MAnswer: CTopic: Section 14.4 Dissociation of Water

36) Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10-3 M in hydronium ion.A) 2.86 × 10-4 MB) 2.86 × 10-11 MC) 2.86 × 10-12 MD) 3.50 × 10-12 MAnswer: CTopic: Section 14.4 Dissociation of Water

37) A solution with a hydrogen ion concentration of 3.25 × 10-2 M is ________ and has a hydroxide concentration of ________.A) acidic, 3.08 × 10-12 MB) acidic, 3.08 × 10-13 MC) basic, 3.08 × 10-12 MD) basic, 3.08 × 10-13 MAnswer: BTopic: Section 14.4 Dissociation of Water

38) A solution with a hydroxide ion concentration of 4.15 × 10-4 M is ________ and has a hydrogen ion concentration of ________.A) acidic, 2.41 × 10-10 MB) acidic, 2.41 × 10-11 MC) basic, 2.41 × 10-10 MD) basic, 2.41 × 10-11 MAnswer: DTopic: Section 14.4 Dissociation of Water

39) If the ionization constant of water, Kw, at 40°C is 2.92 × 10-14, then what is the hydronium ion concentration for a neutral solution?A) [H3O+] < 1.00 × 10-7 M

B) [H3O+] > 1.71 × 10-7 M

C) [H3O+] = 1.71 × 10-7 M

D) [H3O+] < 1.71 × 10-7 MAnswer: CTopic: Section 14.4 Dissociation of Water


40) Normal rainfall has a concentration of OH- that is 3.98 × 10-9. The concentration of H3O+ in normal rainfall isA) greater than 3.98 × 10-9, and the rain is acidic.B) greater than 3.98 × 10-9, and the rain is basic.C) less than 3.98 × 10-9, and the rain is acidic.D) less than 3.98 × 10-9, and the rain is basic.Answer: ATopic: Section 14.4 Dissociation of Water

41) Human tears have a concentration of H3O+ that is 3.16 × 10-8. The concentration of OH- in human tears is A) greater than 3.16 × 10-7 and tears are acidic.B) greater than 3.16 ×10-7 and tears are basic.C) less than 3.16 × 10-7 and tears are acidic.D) less than 3.16 × 10-7 and tears are basic.Answer: BTopic: Section 14.4 Dissociation of Water

42) An acidic solution at 25°C will have a hydronium ion concentration ________ and a pH value ________.A) [H3O+] > 1 × 10-7 M, pH > 7.00

B) [H3O+] > 1 × 10-7 M, pH < 7.00

C) [H3O+] < 1 × 10-7 M, pH > 7.00

D) [H3O+] < 1 × 10-7 M, pH < 7.00Answer: BTopic: Section 14.5 The pH Scale

43) If the ionization constant of water, Kw, at 40°C is 2.92 × 10-14, then what is the hydronium ion concentration and pH for an acidic solution?A) [H3O+] > 1.71 × 10-7 M and pH > 6.77

B) [H3O+] > 1.71 × 10-7 M and pH < 6.77

C) [H3O+] < 1.71 × 10-7 M and pH > 6.77

D) [H3O+] < 1.71 × 10-7 M and pH < 6.77Answer: BTopic: Section 14.5 The pH Scale

44) Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10-3 M hydronium ion.A) 4.65 × 10-12

B) 2.15 × 10-3C) 2.67D) 11.33Answer: C


Topic: Section 14.5 The pH Scale

45) Calculate the pH for an aqueous solution of pyridine that contains 2.15 × 10-4 M hydroxide ion.A) 4.65 × 10-11

B) 2.15 × 10-4 C) 3.67D) 10.33Answer: DTopic: Section 14.5 The pH Scale

46) What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a

hydronium ion concentration of 1.50 × 10-4 M?A) 6.67 × 10-10 M, 4.82B) 6.67 × 10-10 M, 9.18C) 6.67 × 10-11 M, 3.82D) 6.67 × 10-11 M, 10.18Answer: CTopic: Section 14.5 The pH Scale

47) What is the hydronium ion concentration and the pH for an aqueous solution of NH3 that has a

hydroxide ion concentration of 2.25 × 10-3 M?A) 4.44 × 10-11 M, 3.65B) 4.44 × 10-11 M, 10.35C) 4.44 × 10-12 M, 2.65D) 4.44 × 10-12 M, 11.35Answer: DTopic: Section 14.5 The pH Scale

48) What is the hydronium ion concentration of an acid rain sample that has a pH of 3.15?A) 1.41 × 10-11 MB) 7.08 × 10-4 M C) 3.15 MD) 10.85 MAnswer: BTopic: Section 14.5 The pH Scale

49) What is the hydroxide ion concentration of a lye solution that has a pH of 11.20?A) 6.31 × 10-12 MB) 1.58 × 10-3 MC) 2.80 M D) 11.20 MAnswer: BTopic: Section 14.5 The pH Scale


50) What statement is most consistent for an acid with a pH = 3?A) one one-hundredth as strong as an acid with a pH of 5B) half a strong as an acid with a pH = 5C) twice as strong as an acid with a pH of 5D) one hundred times as strong as an acid with a pH = 5Answer: DTopic: Section 14.5 The pH Scale

51) At 25°C, the pH of a vinegar solution is 2.60. What are the values of [H3O+] and [OH-] in the solution?A) 3.99 × 10-12 M, 2.51 × 10-3 MB) 2.51 × 10-3 M, 3.98 × 10-12 MC) 2.51 × 10-3 M, 11.40 MD) 2.60 M, 11.40 MAnswer: BTopic: Section 14.5 The pH Scale

52) What is the approximate pH of a solution X that gives the following responses with the indicators shown?

Indicators HIn In- pH range Solution X

methyl orange red-yellow 3.2-4.4 yellow

methyl red red-yellow 4.8-6.0 yellow

bromothymol blue yellow-blue 6.0-7.6 green

phenolphthalein colorless-pink 8.2-10.0 colorless

A) 3.2 - 4.4 B) 4.8 - 6.0 C) 6.0 - 7.6D) 8.2 - 10.0Answer: CTopic: Section 14.6 Measuring pH





methyl red red-yellow 4.8-6.0 orange

bromothymol blue yellow-blue 6.0-7.6 yellow

phenolphthalein colorless-pink 8.2-10.0 colorless

A) 3.2 - 4.4B) 4.8 - 6.0C) 6.0 - 7.6D) 8.2 - 10.0Answer: BTopic: Section 14.6 Measuring pH




methyl red red-yellow 4.8-6.0 yellow

bromothymol blue yellow-blue 6.0-7.6 blue

phenolphthalein colorless-pink 8.2-10.0 pink

A) 4.8 - 6.0B) 6.0 - 7.6C) 7.6 - 8.2D) > 8.2Answer: DTopic: Section 14.6 Measuring pH

55) What is the pH of a 0.020 M HClO4 solution?A) 0.020B) 0.040C) 1.70D) 12.30Answer: CTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases


56) What is the pH of a 0.020 M RbOH solution?A) 0.020B) 0.040C) 1.70D) 12.30Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

57) What is the pH of a 0.020 M Ba(OH)2 solution?A) 1.40B) 1.70C) 12.30D) 12.60Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

58) What is the pH of a solution prepared by dissolving 0.15 gram of solid CaO (lime) in enough water to make 2.00 L of aqueous Ca(OH)2 (limewater)?

CaO(s) + H2O(l) → Ca2+(aq) + 2 OH-(aq)A) 2.57B) 2.87C) 11.13D) 11.43Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

59) What is the pH of a solution prepared by diluting 25.00 mL of 0.10 M HCl with enough water to produce a total volume of 100.00 mL?A) 1.00B) 1.60C) 2.00D) 3.20Answer: BTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

60) What is the pH of a solution prepared by diluting 25.00 mL of 0.020 M Ba(OH)2 with enough water to produce a total volume of 250.00 mL?A) 2.40B) 2.70C) 11.30D) 11.60Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases


61) What is the pH of a solution made by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCl? Assume that the volumes are additive.A) 0.15B) 0.52C) 0.78D) 1.70Answer: CTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

62) What is the pH of a solution made by mixing 100.0 mL of 0.10 M HNO3, 50.0 mL of 0.20 M HCl, and 100.0 mL of water? Assume that the volumes are additive.A) 0.30B) 0.82C) 1.00D) 1.10Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

63) What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)2 with 50.00 mL of 0.100 M NaOH? Assume that the volumes are additive.A) 12.67B) 12.78C) 12.95D) 13.25Answer: BTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

64) What is the equilibrium constant expression (Ka) for the acid dissociation of hydrocyanic acid HCN? The equation of interest is

HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN-(aq).

A) Ka = ([H3O+][CN-])/([HCN][H2O])

B) Ka = ([H3O+][CN-])/([HCN])

C) Ka = ([HCN][H2O])/([H3O+][CN-])

D) Ka = ([HCN])/([H3O+][CN-])Answer: BTopic: Section 14.8 Equilibria in Solutions of Weak Acids


65) What is the equilibrium constant expression (Ka) for the acid dissociation of nitrous acid HNO2? The equation of interest is

HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq).

A) Ka = ([H3O+][NO2-])/([HNO2][H2O])

B) Ka = ([H3O+][NO2-])/([HNO2])

C) Ka = ([HNO2][H2O])/([H3O+][NO2-])

D) Ka = ([HNO2])/([H3O+][NO2-])Answer: BTopic: Section 14.8 Equilibria in Solutions of Weak Acids

66) Determine the acid dissociation constant for a 0.10 M acetic acid solution that has a pH of 2.87. Acetic acid is a weak monoprotic acid and the equilibrium equation of interest is

CH3COOH(aq) + H2O(l) ⇌H3O+(aq) + CH3CO23-(aq)

A) 1.3 × 10-2 B) 1.3 × 10-3

C) 1.8 × 10-5 D) 1.8 × 10-6Answer: CTopic: Section 14.8 Equilibria in Solutions of Weak Acids

67) Determine the acid dissociation constant for a 0.010 M nitrous acid solution that has a pH of 2.70. Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is

HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2-(aq).

A) 8.0 × 10-3

B) 2.0 × 10-3

C) 5.0 × 10-4

D) 4.0 × 10-4Answer: CTopic: Section 14.8 Equilibria in Solutions of Weak Acids

68) Determine the acid dissociation constant for a 0.020 M formic acid solution that has a pH of 2.74. Formic acid is a weak monoprotic acid and the equilibrium equation of interest is

HCOOH(aq) + H2O(l) ⇌ H3O+(aq) + HCO2-(aq).

A) 1.8 × 10-3

B) 1.8 × 10-4

C) 3.6 × 10-4

D) 3.6 × 10-5Answer: BTopic: Section 14.8 Equilibria in Solutions of Weak Acids


69) The pH of 0.255 M HCN is 4.95. What is the value of Ka for hydrocyanic acid?

A) 1.3 × 10-10

B) 4.9 × 10-10

C) 1.1 × 10-5


70) The pH of 0.150 M CH3CO2H, acetic acid, is 2.78. What is the value of Ka for acetic acid?

A) 2.8 × 10-6

B) 1.9 × 10-5

C) 1.7 × 10-3


71) What is the strongest monoprotic acid of the following set if all the acids are at 0.100 M concentration?A) hydrofluoric acid with Ka = 3.5 × 10-4

B) benzoic acid with Ka = 6.5 × 10-5

C) acetic acid with Ka = 1.8 × 10-5

D) hypochlorous acid with Ka = 3.5 × 10-8

Answer: ATopic: Section 14.8 Equilibria in Solutions of Weak Acids

72) What is the hydronium ion concentration of a 0.100 M acetic acid solution with a Ka = 1.8 × 10-5? The equation for the dissociation of acetic acid is:

CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2-(aq).

A) 1.3 × 10-2 MB) 4.2 × 10-2 MC) 1.3 × 10-3 MD) 4.2 × 10-3 MAnswer: CTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

73) What is the hydronium ion concentration of a 0.100 M hypochlorous acid solution with Ka = 3.5 × 10-8? The equation for the dissociation of hypochlorous acid is:

HOCl(aq) + H2O(l) ⇌ H3O+(aq) + OCl-(aq).

A) 1.9 × 10-4

B) 5.9 × 10-4

C) 1.9 × 10-5

D) 5.9 × 10-5Answer: D


Topic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

74) Para-Aminobenzoic acid (PABA), p-H2NC6H4(COOH), is used in some sunscreens and hair conditioning products. Calculate the pH of an aqueous solution with [PABA] = 0.030 M and Ka = 2.2 × 10-5.A) 1.52B) 3.09C) 4.66D) 6.18Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

75) A tablet containing 500.0 mg of aspirin (acetylsalicylic acid or HC9H7O4) was dissolved in enough

water to make 100 mL of solution. Given that Ka = 3.0 × 10–4 for aspirin, what is the pH of the solution?A) 1.57B) 2.54C) 3.52D) 5.08Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

76) Benzoic acid (C6H5CO2H = HBz) solutions are sometimes used in experiments to determine the molarity of a basic solution of unknown concentration. What is the pH of a 0.100 M solution of benzoic acid if Ka = 6.5 × 10–5 and the equilibrium equation of interest is

HBz(aq) + H2O(l) ⇌ H3O+ + Bz-(aq)?

A) 1.00B) 2.59C) 4.19D) 5.19Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

77) Potassium hydrogen phthalate (molar mass = 204.2 g/mol) is one of the most commonly used acids for standardizing solutions containing bases. KHP is a monoprotic weak acid with Ka = 3.91 × 10–6. Calculate the pH of the solution that results when 0.40 g of KHP is dissolved in enough water to produce 25.0 mL of solution.A) 2.10B) 3.26C) 4.30D) 5.41Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids


78) Vinegar is a 5.0% solution by weight of acetic acid (CH3CO2H) in water. Given that

Ka = 1.8 × 10–5 for acetic acid and assuming the density of vinegar to be 1.00 g/cm3, what is the pH of this vinegar solution?A) 2.00B) 2.41C) 2.87D) 4.74Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

79) Vinegar is a 5.0% solution by weight of acetic acid (CH3CO2H) in water. Given that the pH for

acetic acid is 2.41, the Ka = 1.8 × 10–5 and assuming the density of vinegar to be 1.00 g/cm3, what is the percent dissociation of acetic acid in vinegar?A) 0.47%B) 1.5%C) 4.0%D) 5.0%Answer: ATopic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

80) What is the percent dissociation of a benzoic acid solution with pH = 2.59? The acid dissociation constant for this monoprotic acid is 6.5 × 10–5.A) 0.50%B) 1.5%C) 2.5%D) 3.5%Answer: CTopic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

81) The percent dissociation of acetic acid changes as the concentration of the acid decreases. A 100-fold decrease in acetic acid concentration results in a ________ fold ________ in the percent dissociation.A) 10, increaseB) 10, decreaseC) 100, increaseD) 100, decreaseAnswer: ATopic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

82) Which of the following are weak diprotic acids?A) carbonic acid - H2CO3, hydrosulfuric acid - H2S, acetic acid - CH3CO2HB) formic acid - HCO2H, acetic acid - CH3CO2H, benzoic acid - C6H5CO2HC) carbonic acid - H2CO3, oxalic acid - H2C2O4, sulfurous acid - H2SO3D) hydrocyanic acid - HCN, sulfuric acid - H2SO4, phosphoric acid - H3PO4Answer: CTopic: Section 14.11 Polyprotic Acids


83) What is the second stepwise equilibrium constant expression for phosphoric acid H3PO4?

A) Ka2 = ([H3O+][H2PO4-])/([H3PO4])

B) Ka2 = ([H3O+]2[HPO42-])/([H3PO4])

C) Ka2 = ([H3O+]3[PO43-])/([H3PO4])

D) Ka2 = ([H3O+][HPO42-])/([H2PO4-])Answer: DTopic: Section 14.11 Polyprotic Acids

84) Calculate the pH of a 0.020 M carbonic acid solution, H2CO3(aq), that has the stepwise dissociation

constants Ka1 = 4.3 × 10-7 and Ka2 = 5.6 × 10-11.

A) 1.70B) 4.03C) 6.37D) 10.25Answer: BTopic: Section 14.11 Polyprotic Acids

85) Calculate the pH of a 0.20 M H2SO3 solution that has the stepwise dissociation constants

Ka1 = 1.5 × 10-2 and Ka2 = 6.3 × 10-8.A) 1.26B) 1.32C) 1.82D) 2.52Answer: BTopic: Section 14.11 Polyprotic Acids

86) Calculate the concentration of bicarbonate ion, HCO3-, in a 0.010 M H2CO3 solution that has the

stepwise dissociation constants Ka1 = 4.3 × 10-7 and Ka2 = 5.6 × 10-11.

A) 6.6 × 10-5 MB) 4.3 × 10-7 MC) 4.3 × 10-9 MD) 5.6 × 10-11 MAnswer: ATopic: Section 14.11 Polyprotic Acids

87) What is the pH of a 0.10 M H2Se solution that has the stepwise dissociation constants

Ka1 = 1.3 × 10-4 and Ka2 = 1.0 × 10-11? A) 2.44B) 3.89C) 4.89D) 5.50Answer: ATopic: Section 14.11 Polyprotic Acids


88) What is the selenide ion concentration [Se2-] for a 0.100 M H2Se solution that has the stepwise

dissociation constants of Ka1 = 1.3 × 10-4 and Ka2 = 1.0 × 10-11?

A) 3.6 × 10-3 MB) 1.3 × 10-4 MC) 1.3 × 10-5 MD) 1.0 × 10-11 MAnswer: DTopic: Section 14.11 Polyprotic Acids

89) Which of the following can be classified as a weak base?A) CH3NH2B) NH2OHC) Both CH3NH2 and NH2OHD) Neither CH3NH2 nor NH2OHAnswer: CTopic: Section 14.12 Equilibria in Solutions of Weak Bases

90) What is the pH of a 0.100 M NH3 solution that has Kb = 1.8 × 10-5? The equation for the dissociation of NH3 is

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq).A) 1.87B) 2.87C) 11.13D) 12.13Answer: CTopic: Section 14.12 Equilibria in Solutions of Weak Bases

91) What is the pH of a 0.30 M pyridine solution that has a Kb = 1.9 × 10-9? The equation for the dissociation of pyridine is

C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq).A) 4.62B) 8.72C) 9.38D) 10.38Answer: CTopic: Section 14.12 Equilibria in Solutions of Weak Bases

92) Aniline, (C6H5NH2, Kb = 4.3 × 10-10 at 25°C) is an industrially important amine used in the making of dyes. Determine the pH of an aniline solution made by dissolving 3.90 g of aniline in enough water to make 100 mL of solution. A) 4.87B) 9.13C) 9.74D) 10.74Answer: B


Topic: Section 14.12 Equilibria in Solutions of Weak Bases

93) Determine the ammonia concentration of an aqueous solution that has a pH of 11.50. The equation for the dissociation of NH3 (Kb = 1.8 × 10-5) is

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq).A) 2.5 MB) 0.55 MC) 5.7 × 10-3 MD) 3.2 × 10-3 MAnswer: BTopic: Section 14.12 Equilibria in Solutions of Weak Bases

94) How many grams of pyridine are there in 100 mL of an aqueous solution that has a pH of 9.00? The Kb for pyridine is 1.9 × 10-9 and the equation of interest is

C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq).A) 0.053 gB) 0.42 gC) 0.79 gD) 7.9 gAnswer: BTopic: Section 14.12 Equilibria in Solutions of Weak Bases

95) What is the relationship between Ka and Kb at 25°C for a conjugate acid base pair?

A) Ka × Kb = 1 × 10-14

B) Ka/Kb = 1 × 10-14

C) Kb/Ka = 1 × 10-14

D) Ka + Kb = 1 × 10-14

Answer: ATopic: Section 14.13 Relation Between Ka and Kb

96) Ammonia NH3, has a base dissociation constant of 1.8 × 10-5. What is the conjugate acid of ammonia and what is its acid dissociation constant?A) NH4+, 1.9 × 109

B) NH4+, 1.8 × 10-5

C) NH4+, 5.6 × 10-10

D) NH2-, 5.6 × 10-10

Answer: CTopic: Section 14.13 Relation Between Ka and Kb


97) Methylamine CH3NH2, has a base dissociation constant of 3.7 × 10-4. What is the conjugate acid of methylamine and what is its acid dissociation constant?A) CH3NH3+, 2.7 × 103

B) CH3NH3+, 3.7 × 10-4

C) CH3NH3+, 2.7 × 10-11

D) CH3NH2-, 2.7 × 10-11

Answer: CTopic: Section 14.13 Relation Between Ka and Kb

98) Acetic acid CH3COOH, has an acid dissociation constant of 1.8 × 10-5. What is the conjugate base of acetic acid and what is its base dissociation constant?A) CH3C(OH)2+, 5.6 × 104

B) CH3C(OH)2+, 5.6 × 10-10

C) CH3COOH, 5.6 × 10-10

D) CH3CO2-, 5.6 × 10-10

Answer: DTopic: Section 14.13 Relation Between Ka and Kb

99) Dihydrogen phosphate H2PO4-, has an acid dissociation constant of 6.2 × 10-7. What is the

conjugate base of H2PO4- and what is its base dissociation constant?

A) H3PO4, 1.6 × 106

B) H3PO4, 1.6 × 10-8

C) HPO42-, 1.6 × 106

D) HPO42-, 1.6 × 10-8

Answer: DTopic: Section 14.13 Relation Between Ka and Kb

100) Which of the following salts are acidic?A) LiCl, NaCl, KClB) NH4Cl, CuCl2, AlCl3 C) NaCH3CO2, KCH3CO2, RbCH3CO2D) NaCl, NH4Cl, Na2CO3Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

101) Which one of the following salts, when dissolved in water, produces the solution with the highest pH?A) NaHSO4B) LiClO4C) MgOD) CH3NH3IAnswer: CTopic: Section 14.14 Acid-Base Properties of Salts


102) If an equal number of moles of the weak acid HCN and the strong base KOH are added to water, is the resulting solution acidic, basic, or neutral?A) acidicB) basicC) neutralD) There is insufficient information provided to answer this question.Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

103) Arrange the following 0.10 M aqueous solutions in order of increasing pH: NaOH, HBr, NaCH3CO2, KBr, NH4Br.A) HBr, KBr, NH4Br, NaCH3CO2, NaOHB) NaOH, NaCH3CO2, NH4Br, KBr, HBrC) NaOH, NaCH3CO2, KBr, NH4Br, HBrD) HBr, NH4Br, KBr, NaCH3CO2, NaOHAnswer: DTopic: Section 14.14 Acid-Base Properties of Salts

104) Which one of the following salts, when dissolved in water, produces the solution with the highest pH?A) KIB) KBrC) KClD) KFAnswer: DTopic: Section 14.14 Acid-Base Properties of Salts

105) Which one of the following salts, when dissolved in water, produces the solution with a pH closest to 7.00?A) NH4ClB) BaOC) NaHSO4D) RbIAnswer: DTopic: Section 14.14 Acid-Base Properties of Salts

106) Calculate the pH of a 0.100 M NaCH3CO2 solution. Ka for acetic acid, CH3CO2H, is 1.8 × 10-5.A) 2.87B) 5.13C) 8.87D) 11.13Answer: CTopic: Section 14.14 Acid-Base Properties of Salts


107) Calculate the pH of a of 0.100 M KBrO solution. Ka for hypobromous acid, HBrO, is 2.0 × 10-9.A) 3.15B) 4.85C) 9.15D) 10.85Answer: DTopic: Section 14.14 Acid-Base Properties of Salts

108) Calculate the pH of a 0.100 M CH3NH3Cl solution. Kb for methylamine, CH3NH2, is 3.7 × 10-4.A) 2.22B) 5.78C) 8.22D) 11.78Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

109) Equal volumes of 0.10 M NH3 (Kb = 1.8 × 10-5) and 0.10 M HCN (Ka = 4.9 × 10-10) are mixed together. Will the resulting solution be acidic, basic, or neutral?A) acidicB) basicC) neutralD) insufficient information to solveAnswer: BTopic: Section 14.14 Acid-Base Properties of Salts

110) Which one of the following salts, when dissolved in water, produces the solution with the lowest pH?A) NaClB) NH4ClC) MgCl2D) AlCl3Answer: DTopic: Section 14.14 Acid-Base Properties of Salts

111) What is the identity of M in the hydrate M(H2O)6n+ that has the 0.10 M solution with the lowest pH?A) Li+

B) Na+

C) Mg2+

D) Al3+Answer: DTopic: Section 14.14 Acid-Base Properties of Salts


112) What is the identity of M in the hydrate M(H2O)6n+ that has the 0.10 M solution with the highest pH?A) Li+

B) Na+

C) Mg2+

D) Al3+Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

113) What is the strongest acid among the following?A) HFB) HClC) HBrD) HIAnswer: DTopic: Section 14.15 Factors That Affect Acid Strength

114) What is the strongest acid among the following?A) H2OB) H2SC) H2SeD) H2TeAnswer: DTopic: Section 14.15 Factors That Affect Acid Strength

115) What is the strongest acid among the following?A) HFB) HClC) H2OD) H2SAnswer: BTopic: Section 14.15 Factors That Affect Acid Strength

116) What is the weakest acid among the following?A) SiH4B) PH3C) H2SD) HClAnswer: ATopic: Section 14.15 Factors That Affect Acid Strength


117) Which acid of the following set has the strongest conjugate base?A) CH4B) NH3C) H2OD) HFAnswer: ATopic: Section 14.15 Factors That Affect Acid Strength

118) What is the strongest base among the following?A) ClO-

B) ClO2-

C) ClO3-

D) ClO4-

Answer: ATopic: Section 14.15 Factors That Affect Acid Strength

119) What is the strongest acid among the following?A) H2SO3B) H2SO4C) H2SeO3D) H2SeO4Answer: BTopic: Section 14.15 Factors That Affect Acid Strength

120) What is the strongest acid of the following?A) HOIB) HOBrC) HOClD) All are equivalent.Answer: CTopic: Section 14.15 Factors That Affect Acid Strength

121) What is the strongest acid among the following?A) HIOB) HIO2C) HIO3D) HIO4Answer: DTopic: Section 14.15 Factors That Affect Acid Strength


122) What is the strongest acid among the following?A) CH3CO2HB) ClCH2CO2HC) Cl2CHCO2HD) Cl3CCO2HAnswer: DTopic: Section 14.15 Factors That Affect Acid Strength

123) Identify the Lewis acid that acts as a reactant in the following reaction.Fe(H2O)63+(aq) + 6 CN-(aq) → Fe(CN)63-(aq) + 6 H2O(l)

A) Fe3+B) H2O

C) CN-

D) Fe(H2O)63+

Answer: ATopic: Section 14.16 Lewis Acids and Bases

124) Identify the Lewis acid that acts as a reactant in the following reaction.Co(H2O)63+(aq) + 6 NH3(aq) → Co(NH3)63+(aq) + 6 H2O(l)

A) Co(H2O)63+

B) Co3+C) NH3D) H2OAnswer: BTopic: Section 14.16 Lewis Acids and Bases

125) For Cu2+ and CO2, which will behave as a Lewis acid toward OH- in water?

A) only Cu2+B) only CO2C) Cu2+ and CO2D) neither Cu2+ nor CO2Answer: CTopic: Section 14.16 Lewis Acids and Bases

126) Which one of the following is not considered to be a Lewis base?A) H2OB) NH3C) NH4+

D) Cl-Answer: CTopic: Section 14.16 Lewis Acids and Bases


127) Which one of the following is least able to behave as a Lewis base?A) CH3NH2B) (CH3)2NHC) (CH3)3N

D) (CH3)3NH+

Answer: DTopic: Section 14.16 Lewis Acids and Bases

128) The compound BF3 can be described as a(n) ________.A) Arrhenius acidB) Br∅nsted-Lowry acidC) Lewis acidD) Lewis baseAnswer: CTopic: Section 14.16 Lewis Acids and Bases

129) Identify the set of Lewis acids.A) BH3, BF3, Cu2+, CO2B) Cl-, OH-, NH3, H2O

C) H3PO4, H2PO4-, HPO42-, PO43-

D) CH3-, NH2-, OH-, F-

Answer: ATopic: Section 14.16 Lewis Acids and Bases

130) Which one of the following is expected to be the strongest Lewis acid?A) FeB) Fe+

C) Fe2+

D) Fe3+Answer: DTopic: Section 14.16 Lewis Acids and Bases


In the following reaction the unshaded spheres represent H atoms.

131) Identify the Br∅nsted-Lowry acids.A) (1) and (3)B) (1) and (4)C) (2) and (3)D) (2) and (4)Answer: BTopic: Conceptual Problems

132) Identify the Br∅nsted-Lowry bases.A) (1) and (3)B) (1) and (4)C) (2) and (3)D) (2) and (4)Answer: CTopic: Conceptual Problems


133) Identify the Br∅nsted-Lowry acids.A) (1) and (3)B) (1) and (4)C) (2) and (3)D) (2) and (4)Answer: CTopic: Conceptual Problems


134) Identify the Br∅nsted-Lowry bases.A) (1) and (3)B) (1) and (4)C) (2) and (3)D) (2) and (4)Answer: BTopic: Conceptual Problems


135) Identify the Br∅nsted-Lowry acid/base conjugate pairs.A) (1)/(2) and (3)/(4)B) (1)/(3) and (2)/(4)C) (1)/(4) and (2)/(3)Answer: BTopic: Conceptual Problems


136) Identify the Br∅nsted-Lowry acid/base conjugate pairs.A) (1)/(2) and (3)/(4)B) (1)/(3) and (2)/(4)C) (1)/(4) and (2)/(3)Answer: BTopic: Conceptual Problems


The following pictures represent aqueous solutions of three acids HA (A = X, Y, or Z); water molecules have been omitted for clarity.

137) Arrange the three acids in order of increasing acid strength.A) HZ < HY < HXB) HY < HZ < HXC) HZ < HX < HYD) HX < HZ < HYAnswer: DTopic: Conceptual Problems

138) Which acid, if any, is a strong acid?A) All are strong acids.B) HX and HZC) HYD) None are strong acids.Answer: CTopic: Conceptual Problems

139) Which acid has the smallest value of Ka?A) HXB) HYC) HZD) All have the same Ka value.Answer: ATopic: Conceptual Problems


140) Which acid has the lowest percent dissociation?A) HXB) HYC) HZD) All have the same percent dissociation.Answer: ATopic: Conceptual Problems

141) Which acid solution has the lowest pH?A) HXB) HYC) HZD) All have the same pH.Answer: BTopic: Conceptual Problems

142) Which of the above pictures represents a solution of a weak diprotic acid H2A for which Ka1 >> Ka2? (Water molecules have been omitted for clarity.)

A) picture (a)B) picture (b)C) picture (c)D) picture (d)Answer: CTopic: Conceptual Problems


143) Which of the above pictures represents a solution of a diprotic acid H2A for which Ka1 = and

Ka2 is exceptionally small. (Water molecules have been omitted for clarity.)A) picture (a)B) picture (b)C) picture (c)D) picture (d)Answer: BTopic: Conceptual Problems

The following pictures represent equal volumes of aqueous solutions of three acids HA (A = X, Y, or Z); water molecules have been omitted for clarity.

144) Arrange the acids in order of increasing acid strength.A) HZ < HY < HXB) HY < HZ < HXC) HZ < HX < HYD) HX < HZ < HYAnswer: BTopic: Conceptual Problems

145) Arrange the acids in order of increasing value of Ka.A) Ka(HZ) < Ka(HY) < Ka(HX)B) Ka(HY) < Ka(HZ) < Ka(HX)C) Ka(HZ) < Ka(HX) < Ka(HY)D) Ka(HX) < Ka(HZ) < Ka(HY)Answer: BTopic: Conceptual Problems

146) Arrange the acids in order of increasing value of percent dissociation.A) HZ < HY < HXB) HY < HZ < HXC) HZ < HX < HYD) HX < HZ < HYAnswer: BTopic: Conceptual Problems


147) Arrange the acids in order of increasing pH.A) HZ < HY < HXB) HY < HZ < HXC) HZ < HX < HYD) HX < HZ < HYAnswer: DTopic: Conceptual Problems

148) Arrange the conjugate bases (A- = X-, Y-, or Z-) in order of increasing base strength.A) Z- < Y- < X-

B) Y- < Z- < X-

C) Z- < X- < Y-

D) X- < Z- < Y-Answer: DTopic: Conceptual Problems

149) Arrange the conjugate bases (A- = X-, Y-, or Z-) in order of increasing value of Kb.

A) Kb(Z-) < Kb(Y-) < Kb(X-)

B) Kb(Y-) < Kb(Z-) < Kb(X-)

C) Kb(Z-) < Kb(X-) < Kb(Y-)

D) Kb(X-) < Kb(Z-) < Kb(Y-)Answer: DTopic: Conceptual Problems


150) The following pictures represent solutions of three salts NaA (A- = X-, Y-, or Z-); water molecules and Na+ ions have been omitted for clarity. Arrange the three A- ions in order of decreasing base strength.

A) X- > Y- > Z-

B) X- > Z- > Y-

C) Y- > Z- > X-

D) Z- > Y- > XZ-Answer: BTopic: Conceptual Problems


The following pictures represent solutions of three salts MA; water molecules have been omitted for clarity. Dotted spheres represent Ay- ions; gray spheres represent Mx+ ions; black spheres represent oxygen atoms; and unshaded spheres represent hydrogen atoms.

151) Which picture represents an acidic salt?A) (1)B) (2)C) (3)D) None of theseAnswer: BTopic: Conceptual Problems

152) Which picture represents a neutral salt?A) (1)B) (2)C) (3)D) None of theseAnswer: CTopic: Conceptual Problems

153) Which picture represents a basic salt?A) (1)B) (2)C) (3)D) None of theseAnswer: ATopic: Conceptual Problems


154) Of the elements indicated on the periodic table shown above, which forms the strongest binary acid, H2X or HX, where X = A, B, C, or D?A) AB) BC) CD) DAnswer: DTopic: Conceptual Problems

155) Of the elements indicated on the periodic table shown above, which forms the weakest binary acid, H2X or HX, where X = A, B, C, or D?

A) AB) BC) CD) DAnswer: ATopic: Conceptual Problems

156) Of the elements indicated on the periodic table shown above, which forms the strongest oxoacid acid with the formula H2XO3 or HXO3, where X = A, B, C, or D?

A) AB) BC) CD) DAnswer: BTopic: Conceptual Problems

157) Of the elements indicated on the periodic table shown above, which forms the weakest oxoacid acid with the formula H2XO3 or HXO3, where X = A, B, C, or D?

A) AB) BC) CD) DAnswer: CTopic: Conceptual Problems


158) SO3 reacts with H2O to form H2SO4. Which picture below correctly represents the curved arrow notation for the initial Lewis acid-Lewis base interaction in this reaction; what is the Lewis acid and the Lewis base?

A) Picture (1) is correct; H2O is the Lewis acid and SO3 is the Lewis base.B) Picture (1) is correct; SO3 is the Lewis acid and H2O is the Lewis base.C) Picture (2) is correct; H2O is the Lewis acid and SO3 is the Lewis base.D) Picture (2) is correct; SO3 is the Lewis acid and H2O is the Lewis base.Answer: DTopic: Conceptual Problems

159) CO2 reacts with H2O to form HCO3- and H+. Which picture below correctly represents the curved arrow notation for the initial Lewis acid-Lewis base interaction in this reaction; what is the Lewis acid and the Lewis base?

(1) (2)

A) Picture (1) is correct; H2O is the Lewis acid and CO2 is the Lewis base.B) Picture (1) is correct; CO2 is the Lewis acid and H2O is the Lewis base.C) Picture (2) is correct; H2O is the Lewis acid and CO2 is the Lewis base.D) Picture (2) is correct; CO2 is the Lewis acid and H2O is the Lewis base.Answer: BTopic: Conceptual Problems


160) BF3 and NH3 undergo a Lewis acid-base reaction forming an adduct. Which picture below correctly represents the curved arrow notation for the initial Lewis acid-Lewis base interaction in this reaction; what is the Lewis acid and the Lewis base?

A) Picture (1) is correct; NH3 is the Lewis acid and BF3 is the Lewis base.B) Picture (2) is correct; BF3 is the Lewis acid and NH3 is the Lewis base.C) Picture (3) is correct; NH3 is the Lewis acid and BF3 is the Lewis base.D) Picture (4) is correct; BF3 is the Lewis acid and NH3 is the Lewis base.Answer: BTopic: Conceptual Problems

14.2 Algorithmic Questions

1) When dissolved in water, which compound is generally considered to be an Arrhenius acid? A) H NO2 B) KOHC) Li F D) CH3OH Answer: ATopic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

2) Which Br∅nsted-Lowry acid is not considered to be a strong acid in water? A) H IB) H Br C) H2S O3D) H NO3Answer: CTopic: Section 14.2 Acid Strength and Base Strength


3) Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10- 6 M in hydroxide ion.A) 4.00 × 10- 7 MB) 4.00 × 10- 8 MC) 4.00 × 10- 9 MD) 5.00 × 10- 9 MAnswer: CTopic: Section 14.4 Dissociation of Water

4) Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10- 4 M in hydronium ion.A) 2.86 × 10- 3 MB) 2.86 × 10- 10 MC) 2.86 × 10- 11 MD) 3.50 × 10- 11 MAnswer: CTopic: Section 14.4 Dissociation of Water

5) A solution with a hydrogen ion concentration of 3.25 × 10- 6 M is ________ and has a hydroxide ion concentration of ________. A) acidic, 3.08 × 10- 8 MB) acidic, 3.08 × 10- 9 MC) basic, 3.08 × 10- 8 MD) basic, 3.08 × 10- 9 MAnswer: BTopic: Section 14.4 Dissociation of Water

6) A solution with a hydroxide ion concentration of 4.15 × 10- 6 M is ________ and has a hydrogen ion concentration of ________. A) acidic, 2.41 × 10- 8 MB) acidic, 2.41 × 10- 9 MC) basic, 2.41 × 10- 8 MD) basic, 2.41 × 10- 9 MAnswer: DTopic: Section 14.4 Dissociation of Water

7) Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10-3 M hydronium ion. A) 4.65 × 10-12 MB) 2.15 × 10-3 MC) 2. 67D) 11. 33Answer: CTopic: Section 14.5 The pH Scale


8) Calculate the pH for an aqueous solution of pyridine that contains 2.15 × 10-4 M hydroxide ion.A) 4.65 × 10-11

B) 2.15 × 10-4 C) 3. 67D) 10. 33Answer: DTopic: Section 14.5 The pH Scale

9) What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a hydronium ion concentration of 1.50 × 10-2 M?A) 6.67 × 10- 12 M, 2.82B) 6.67 × 10- 12 M, 11.18C) 6.67 × 10- 13 M, 1.82D) 6.67 × 10- 13 M, 12.17Answer: CTopic: Section 14.5 The pH Scale

10) What is the hydronium ion concentration and the pH for an aqueous solution of NH3 that has a

hydroxide ion concentration of 2.25 × 10-2 M?A) 4.44 × 10- 12 M and 2.65B) 4.44 × 10- 12 M and 11.35C) 4.44 × 10- 13 M and 1.65D) 4.44 × 10- 13 M and 12.35Answer: DTopic: Section 14.5 The pH Scale

11) What is the hydronium ion concentration of an acid rain sample that has a pH of 3. 45? A) 2.82 × 10-11 MB) 3.55 × 10-4 M C) 3. 45 MD) 10. 55 MAnswer: BTopic: Section 14.5 The pH Scale

12) What is the hydroxide ion concentration of a lye solution that has a pH of 9.20? A) 6.31 × 10- 10 MB) 1.58 × 10- 5 MC) 4.80 M D) 9.20 MAnswer: BTopic: Section 14.5 The pH Scale


13) What is the pH of a 0. 020 M HClO4 solution?A) 0. 020B) 0. 040C) 1.70D) 12.30Answer: CTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

14) What is the pH of a 0.0 40 M Ba(OH)2 solution?A) 1.10B) 1.40C) 12.60D) 12.90Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

15) What is the pH of a solution prepared by dissolving 0. 45 grams of solid CaO (lime) in enough water to make 2.00 L of aqueous Ca(OH)2 (limewater)?

CaO(s) + H2O(l) → Ca2+(aq) + 2 OH-(aq)A) 2.10B) 2.40C) 11.60D) 11.90Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

16) What is the pH of a solution prepared by diluting 20.00 mL of 0.10 M HCl with enough water to produce a total volume of 100.00 mL?A) 1.00B) 1. 70C) 2.00D) 3.40Answer: BTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

17) What is the pH of a solution prepared by diluting 100.00 mL of 0.020 M Ba(OH)2 with enough water to produce a total volume of 250.00 mL?A) 1.80B) 2. 10C) 11.90D) 12.20Answer: DTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases


18) What is the pH of a solution prepared by mixing 100.00 mL of 0.20 M HCl with 150.00 mL of 0. 10 M HCl? Assume that the volumes are additive. A) 0. 17B) 0. 52C) 0. 85D) 1.70Answer: CTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

19) What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)2 with 50.00 mL of 0. 300 M NaOH? Assume that the volumes are additive.A) 13.05B) 13.10C) 13.28D) 13.58Answer: BTopic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

20) What is the hydronium ion concentration of a 0. 500 M acetic acid solution with Ka = 1.8 × 10-5? The equation for the dissociation of acetic acid is:

CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2-(aq).

A) 3.0 × 10-2 MB) 4.2 × 10-2 MC) 3.0 × 10-3 MD) 4.2 × 10-3 MAnswer: CTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

21) What is the hydronium ion concentration of a 0. 150 M hypochlorous acid solution with Ka = 3.5 × 10-8? The equation for the dissociation of hypochlorous acid is:

HOCl(aq) + H2O(l) ⇌ H3O+(aq) + OCl-(aq).

A) 1.9 × 10-4 MB) 7.2 × 10-4 MC) 2.8 × 10-5 MD) 7.2 × 10-5 MAnswer: DTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids


22) Potassium hydrogen phthalate (molar mass = 204.2 g/mol)is one of the most commonly used acids for standardizing solutions containing bases. KHP is a monoprotic weak acid with Ka = 3.91 × 10-6. Calculate the pH of the solution that results when 0. 50 g of KHP is dissolved in enough water to produce 25.0 mL of solution. A) 2.05B) 3. 21C) 4. 40D) 5.41Answer: BTopic: Section 14.9 Calculating Equilibrium Concentrations in Solutions of Weak Acids

23) Calculate the pH of a 0. 080 M carbonic acid solution, H2CO3(aq), that has the stepwise

dissociation constants Ka1 = 4.3 × 10-7 and Ka2 = 5.6 × 10-11. A) 1.10B) 3.73C) 6.37D) 10.25Answer: BTopic: Section 14.11 Polyprotic Acids

24) Calculate the pH of a 0. 60 M H2SO3, solution that has the stepwise dissociation constants

Ka1 = 1.5 × 10-2 and Ka2 = 6.3 × 10-8.A) 1.02B) 1.06C) 1.82D) 2.04Answer: BTopic: Section 14.11 Polyprotic Acids

25) Calculate the concentration of bicarbonate ion, HCO3-, in a 0.0 10 M H2CO3 solution that has the

stepwise dissociation constants Ka1 = 4.3 × 10-7 and Ka2 = 5.6 × 10-11.

A) 6.6 × 10- 5 MB) 4.3 × 10-7 MC) 4.3 × 10- 9 MD) 5.6 × 10-11 MAnswer: ATopic: Section 14.11 Polyprotic Acids

26) What is the pH of a 0. 40 M H2Se solution that has the stepwise dissociation constants

Ka1 = 1.3 × 10-4 and Ka2 = 1.0 × 10-11?A) 2. 14B) 3.89C) 4. 28D) 5. 57Answer: ATopic: Section 14.11 Polyprotic Acids


27) What is the selenide ion concentration [Se2-] for a 0. 100 M H2Se solution that has the stepwise

dissociation constants of Ka1 = 1.3 × 10-4 and Ka2 = 1.0 × 10-11?

A) 3.6 × 10-3 MB) 1.3 × 10-4 MC) 1.3 × 10-5 MD) 1.0 × 10-11 MAnswer: DTopic: Section 14.11 Polyprotic Acids

28) What is the pH of a 0. 200 M NH3 solution that has Kb = 1.8 × 10-5? The equation for the dissociation of NH3 is

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq). A) 2.02B) 2. 72C) 11. 98D) 11.28Answer: DTopic: Section 14.12 Equilibria in Solutions of Weak Bases

29) What is the pH of a 0.30 M pyridine solution that has Kb = 1.9 × 10-9? The equation for the dissociation of pyridine is

C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq).A) 4. 62B) 8.72C) 9. 38D) 10. 38Answer: CTopic: Section 14.12 Equilibria in Solutions of Weak Bases

30) Aniline, (C6H5NH2, Kb = 4.3 × 10-10 at 25°C) is an industrially important amine used in the making of dyes. Determine the pH of an aniline solution made by dissolving 6.90 g of aniline in enough water to make 100 mL of solution. A) 4. 75B) 9. 25C) 9. 50D) 10. 50Answer: BTopic: Section 14.12 Equilibria in Solutions of Weak Bases


31) Determine the ammonia concentration of an aqueous solution that has a pH of 11. 00. The equation for the dissociation of NH3 (Kb = 1.8 × 10-5) is

NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq).A) 3.0 MB) 0. 056 MC) 1.8 × 10- 2 MD) 1.0 × 10-3 MAnswer: BTopic: Section 14.12 Equilibria in Solutions of Weak Bases

32) Which one of the following salts, when dissolved in water, produces the solution with the highest pH? A) KH CO3B) CsClO4C) RaOD) CH3CH3NH3ClAnswer: CTopic: Section 14.14 Acid-Base Properties of Salts

33) If an equal number of moles of the weak acid HCN and the strong base KOH are added to water, is the resulting solution acidic, basic, or neutral? A) acidicB) basicC) neutralD) There is insufficient information provided to answer this question.Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

34) Which one of the following salts, when dissolved in water, produces the solution with the highest pH?A) RbIB) RbBrC) RbClD) RbFAnswer: DTopic: Section 14.14 Acid-Base Properties of Salts

35) Which one of the following salts, when dissolved in water, produces the solution with a pH closest to 7.00?A) NH4Br B) Ca OC) K HSO4D) Cs IAnswer: DTopic: Section 14.14 Acid-Base Properties of Salts


36) Calculate the pH of a 0.800 M NaCH3CO2 solution. Ka for acetic acid, CH3CO2H, is 1.89 × 10-5.A) 2. 42B) 4.68C) 9.32D) 11. 58Answer: CTopic: Section 14.14 Acid-Base Properties of Salts

37) Calculate the pH of a 1.60 M KBrO solution. Ka for hypobromous acid, HBrO, is 2.0 × 10-9.A) 2.55B) 4.25C) 9. 75D) 11.45Answer: DTopic: Section 14.14 Acid-Base Properties of Salts

38) Calculate the pH of a 1.60 M CH3NH3Cl solution. Kb for methylamine, CH3NH2, is 3.7 × 10-4.A) 1.61B) 5. 18C) 8. 82D) 12.39Answer: BTopic: Section 14.14 Acid-Base Properties of Salts

39) Which one of the following salts, when dissolved in water, produces the solution with the lowest pH?A) NaClB) KClC) MgCl2D) AlCl3Answer: DTopic: Section 14.14 Acid-Base Properties of Salts


14.3 Short Answer Questions

1) The Br∅nsted-Lowry acids in the chemical equation below are ________ and ________.HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2–(aq)

Answer: HNO2, H3O+

Topic: Section 14.1 Acid-Base Concepts: The Bronsted-Lowry Theory

2) The equilibrium constant for the reaction below has the value Ka = 3.5 × 10-4. In this reaction the stronger Br∅nsted-Lowry acid is ________ and the weaker Br∅nsted-Lowry acid is ________.

HF(aq) + H2O(l) ⇌ H3O+(aq) + F–(aq)

Answer: H3O+, HFTopic: Section 14.2 Acid Strength and Base Strength

3) A proton hydrated by four water molecules has the formula ________.Answer: H9O4+

Topic: Section 14.3 Hydrated Protons and Hydronium Ions

4) The number of waters of hydration in the hydrate proton H7O3+ is ________. Answer: 3Topic: Section 14.3 Hydrated Protons and Hydronium Ions

5) An acidic solution with hydronium ion concentration [H+] = 1.60 × 10–3 M has a hydroxide ion concentration [OH–] = ________.Answer: 6.25 × 10–12 MTopic: Section 14.4 Dissociation of Water

6) The concentration of H3O+ in human sweat can be as low as 2.5 × 10-6. The concentration of OH- in the sweat is ________, and this solution is ________ (acidic, basic, neutral).Answer: 4.0 × 10-9, acidicTopic: Section 14.4 Dissociation of Water

7) Undersea flora prefer a maximum concentration of OH- of 1.58 × 10-5. The concentration of H3O+ in the seawater is ________, and this solution is ________ (acidic, basic, neutral). Answer: 6.31 × 10-10, basicTopic: Section 14.4 Dissociation of Water

8) At the normal body temperature of 37°C, Kw = 2.42 × 10-14. The H3O+ concentration of normal

blood ranges from 3.5 × 10-8 to 4.5 × 10-8. The OH- concentration of normal blood ranges from ________ to ________, and blood is ________ (acidic, basic, neutral).Answer: 2.2 × 10-7, 2.9 × 10-7, basicTopic: Section 14.4 Dissociation of Water


9) At 50°C the value of Kw is 5.5 × 10–14, and the pH of a neutral solution at 50°C is ________.Answer: 6.63Topic: Section 14.5 The pH Scale

10) One way to prepare a solution with a pH of 10.00 is to dissolve ________ grams of CaO in enough water to make 500 mL of solution. Answer: 1.4 × 10-3Topic: Section 14.5 The pH Scale

11) Bromothymol blue indicator changes color from yellow at a pH of 6.0 to blue at a pH of 7.6. Phenol red indicator changes color from yellow at a pH of 6.8 to red at a pH of 8.4. A sample of pancreatic fluid having [OH-] = 1.258 × 10-6 would impart a ________ color to bromothymol blue and a ________ color to phenol red. Answer: blue, redTopic: Section 14.6 Measuring pH

12) Bromothymol blue indicator changes color from yellow at a pH of 6.0 to blue at a pH of 7.6. Methyl red indicator changes color from red at a pH of 4.4 to yellow at a pH of 6.2. A sample of saliva having [H3O+] = 6.310 × 10-7 would impart a ________ color to bromothymol blue and a ________ color to methyl red. Answer: yellow, yellowTopic: Section 14.6 Measuring pH

13) The pH of a 0.025 M KOH solution is ________.Answer: 12.40Topic: Section 14.7 The pH in Solutions of Strong Acids and Strong Bases

14) The value of Ka for a 0.250 M HCN solution having a pH of 4.956 is ________.

Answer: 4.90 × 10–10Topic: Section 14.8 Equilibria in Solutions of Weak Acids

15) In order for the reaction HA + HSO3- ⇌ A- + H2SO3 to have an equilibrium constant Kc < 1, the

Ka of HA must be ________ (greater, less) than the Ka of HSO3-.Answer: lessTopic: Section 14.8 Equilibria in Solutions of Weak Acids

16) In order for the reaction A- + H2CO3 ⇌ HA + HCO3- to have an equilibrium constant Kc < 1, the Ka of HA must be ________ (greater, less) than the Ka of H2CO3. Answer: greaterTopic: Section 14.8 Equilibria in Solutions of Weak Acids

17) A 1.25 × 10-4 M solution of the anti-inflammatory drug naproxen has a pH = 4.2. The Ka and pKa of naproxen are ________ and ________. Answer: 6.3 × 10-5, 4.2Topic: Section 14.8 Equilibria in Solutions of Weak Acids


18) Phenobarbital is an antiepileptic drug with a water solubility of 4.3 × 10-3 M and pKa = 7.4. What is

the pH and percent ionization of 4.3 × 10-3 M phenobarbital? Answer: 4.88, 0.30%Topic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

19) Phenobarbital has a pKa = 7.4. Compared to a 1.0 × 10-3 M solution, 1.0 × 10-4 M phenobarbital will have a ________ (higher, lower) pH and a ________ (higher, lower) percent ionization. Answer: higher, higherTopic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

20) Erythromycin is a basic antimicrobial with pKb = 5.2. A 1.0 × 10-3 M solution of erythromycin has a pH of and a percent ionization. Answer: 9.9, 8%Topic: Section 14.10 Percent Dissociation in Solutions of Weak Acids

21) A 0.050 M solution of hydroxylamine, NH2OH, having Kb = 9.1 × 10–9 has a pH of ________.Answer: 9.33Topic: Section 14.12 Equilibria in Solutions of Weak Bases

22) A 0.10 M KNO2 solution will have a pH ________ seven.Answer: greater thanTopic: Section 14.14 Acid-Base Properties of Salts

23) The acid strength of an oxoacid having the general formula HnYOm increases as the electronegativity of Y ________ and as the oxidation number of Y ________.Answer: increases, increasesTopic: Section 14.15 Factors That Affect Acid Strength

24) In the aquation reaction Co2+ + 6 H2O → [Co(H2O)6]2+, the Lewis acid is ________ and the Lewis base is________.Answer: Co2+, H2OTopic: Section 14.16 Lewis Acids and Bases

25) In the reaction between NO2 and H2O that produces HNO3, the Lewis acid is ________ and the Lewis base is ________. Answer: NO2, H2OTopic: Section 14.16 Lewis Acids and Bases


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