Test Bank Chapter 15 Aqueous Acid–base Equilibria 729

CHAPTER 15

AQUEOUS ACID–BASE EQUILIBRIA

CHAPTER STUDY OBJECTIVES

1. Use the Brønsted–Lowry theory of acids and bases.

SKILLS TO MASTER: Calculating concentrations in solutions of strong acids and bases

KEY CONCEPTS: Water can act as an acid or a base. Any proton donor and the species generated by removing one of its protons are called a conjugate acid–base pair.

The water autohydrolysis equilibrium exists in any aqueous solution.

K_w [H₃O ]_eq[OH^-]_eq 1.0 X10⁻¹⁴ at 25°C in any aqueous solution.

2. Relate pH to concentrations of ions in solution.

SKILLS TO MASTER: Calculating pH; relating pH with pOH

KEY CONCEPTS: pH is a logarithmic scale. A change of 1 pH unit is a 10-fold change of [H₃O⁺(aq)].

3. Calculate concentrations and pH in weak acid and base solutions.

SKILLS TO MASTER: Calculating Ka from pH; calculating % hydrolysis and concentrations in solutions of weak acids; calculating concentrations in solutions of weak bases

KEY CONCEPTS: In a solution of a weak acid, only a small fraction of the protons are transferred to the base. In a solution of a weak base, only a small fraction of the protons are transferred from the acid.

4. Recognize and name some common acids and bases.

SKILLS TO MASTER: Naming oxoacids; writing the reaction for hydrolysis of a carboxylic acid; naming other weak acids; naming some weak bases

KEY CONCEPTS: Oxoacids contain an inner atom bonded to a variable number of oxygen atoms and acidic OH groups. Carboxylic acids have the general formula RCO₂H.

5. Calculate the pH of solutions of salts of weak acids or bases.

SKILLS TO MASTER: Calculating the pH of a solution of the salt of a weak acid; calculating the pH of a solution of the salt of a weak base

KEY CONCEPTS: Whenever two equilibria are added, the net equilibrium constant is the product of the individual ones. In any aqueous system, K_aK_b = K_w and pK_a + pK_b = pK_w. Salts of weak acids are basic in aqueous solution; salts of weak bases are acidic in aqueous solution.

6. Explain the factors that contribute to the strength of an acid.

SKILLS TO MASTER: Understanding how structural factors influence the acidity of binary hydrides and oxoacids; understanding how structural factors influence the acidity of carboxylic acids

KEY CONCEPTS: The strength of an oxoacid or carboxylic acid increases as electron density is withdrawn from the OH bond. Successive K_a values of polyprotic acids are smaller than previous ones because of increasing negative charge on the anion.

7. Calculate concentrations in solutions involving multiple equilibria.

SKILLS TO MASTER: Calculating the pH and concentrations in solutions of polyprotic acids; calculating the pH and concentrations in solutions of salts of polyprotic acids

Multiple Choice QUESTIONS

1. A 45.0 mL sample of 0.15 M HCl is added to 38 mL of 0.2 M NaOH. What is the [H₃O⁺] of the resulting solution?

a) 8.5 x 10^-4 M

b) 0.010 M

c) 7.6 x 10^-3‑ M

d) 9.8 x 10^-13 M

e) 1.02 x 10^-14 M

Difficulty: Medium

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

2. Identify the acids in the following reaction:

H₂PO₄^- + H₂O ⇌ H₃O⁺ + HPO₄²-

a) H₂PO₄^-

b) H₃O⁺

c) H₂PO₄^- and H₃O⁺

d) H₂O and H₃O⁺

e) H₂O and HPO₄^2-

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

3. Identify the bases in the following reaction:

H₂PO₄^- + OH^- ⇌ H₂O + HPO₄^2-

a) H₂PO₄^-

b) OH^-

c) H₂PO₄^- and H₂O and H₃O⁺

d) OH^- and HPO₄^2-

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

4. What is the pH of pure water at 99^oC, if K_w (99^oC) is 8.836 x 10^-13?

a) 7.00

b) –6.02

c) 6.02

d) 12.08

e) 13.88

Difficulty: Medium

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

Feedback: a) pH = 7 at 298; b) negative sign; c) correct answer; d) – log (8.836 x 10^-13); e) – ln (9.4 x 10^-7)

5. A 245.0 mL sample of 0.15 M Ba(OH)₂ is added to 438 mL of 0.2 M HNO₃. What is the pH of the resulting solution?

a) 0.021

b) 1.68

c) 12.32

d) 0.70

e) 13.30

Difficulty: Medium

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

6. A 0.1 mL sample of 0.01 M HCl is added to 1000 L of water at 298ºK. What is the pH of the resulting solution?

a) 2.0

b) 5.0

c) 7.0

d) 10.0

e) 12.0

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

7. A 0.001 mL sample of 0.01 M Ba(OH)₂ is added to 1000 L of water at 298ºK. What is the pH of the resulting solution?

a) 2.0

b) 5.0

c) 7.0

d) 10.0

e) 12.0

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

8. To have solutions of HCl and acetic acid (CH₃CO₂H) with the same pH, which of the following needs to be done?

a) The concentration of each solution needs to be the same.

b) The concentration of HCl needs to be higher.

c) The concentration of acetic acid needs to be higher.

d) The solutions can never have the same pH.

e) Volume of acetic acid solution must be lower.

Difficulty: Easy

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

9. A 1.35 g sample of ammonium chloride is added to sufficient water to give 150.0 mL of solution whose pH is less than 7.0. Several dissociation reactions occur. Which of the following goes essentially to completion?

a) H₂O  H⁺ + OH^-

b) NH₄⁺  NH₃ + H⁺

c) NH₃  NH₂^- + H⁺

d) NH₄Cl  NH₄⁺ + Cl^-

e) NH₃ + H₂O OH^- + NH₄⁺

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

10. A 1.35 g sample of ammonium chloride is added to sufficient water to give 150.0 mL of solution. Several reactions occur. Which of the following will determine the pH of the solution?

a) 2H₂O ⇌ H₃O⁺ + OH^-

b) NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺

c) NH₃ + H₂O ⇌ NH₂^- + H₃O⁺

d) NH₄Cl  NH₄⁺ + Cl^-

e) NH₃ + H₂O OH^- + NH₄⁺

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

11. Identify the major species present in a 0.15 M solution of sodium monohydrogen phosphate, Na₂HPO₄.

a) Na⁺, PO₄^3-, H⁺, H₂O

b) Na₂HPO₄, H₂O

c) Na⁺, H₂PO₄^-, OH^-, H₂O

d) Na⁺, HPO₄^2-, H₂O

e) Na₂HPO₄, Na⁺, HPO₄^2-, H₂O

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

12. Which of the following is a weak base?

a) CH₃OH

b) KOH

c) CH₃CO₂H

d) NH₄Cl

e) CH₃CH₂CH₂CO₂^-

Difficulty: Easy

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

13. Which of the following is a weak acid?

a) CH₃OH

b) NaOH

c) CH₃CO₂^-

d) NH₄Cl

e) CH₃CH₂CH₂CO₂CH₃

Difficulty: Medium

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

14. Which of the following is a weak base?

a) NaOH

b) CH₃CO₂H

c) (CH₃)₂NH

d) KOH

e) HClO₂

Difficulty: Medium

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

15. Which of the following is the conjugate base of the dihydrogenphosphate ion, H₂PO₄^-?

a) H₃PO₄

b) NaH₂PO₄

c) OH^-

d) HPO₄^2-

e) PO₄^3-

Difficulty: Hard

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

16. Which is the conjugate acid of HAsO₄^2-?

a) H₃AsO₄

b) H₃O⁺

c) OH^-

d) H₂AsO₄^2-

e) AsO₄^3-

Difficulty: Hard

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

17. The K_as for HClO₂, HClO, HIO and HIO₃ are 1.1x10^-2, 4.0x10^-8, 3.2x10^-11, and 1.7x10^-1, respectively. Which of the following is the strongest base?

a) ClO₂^-

b) ClO^‑

c) IO^-

d) IO₃^-

Difficulty: Easy

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

Feedback: Recognize strength of the conjugate base is inversely proportional to the strength of the weak acid.

18. A solution of total volume 0.50 L was prepared by the addition of 0.10 moles of KF to sufficient water. From the following, select the major species and the pH of the solution.

a) K⁺, HF; H O^-, H₂O, pH = 8.23

b) K⁺, F^-; H⁺, H₂O, pH = 5.76

c) K⁺, H₂O, F^-, pH = 8.23

d) K⁺, H₂O, F^-, pH = 5.76

e) KF, H₃O⁺, 6.27

Difficulty: Medium

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

19. Although you may NOT think of these compounds as being acids, your organic chemistry instructor probably will. Consider the H atoms in bold print in the following compounds.

A= CH₃CH₂(C=O)CH₃ B = CH₃CH₂(C=O)CH₃ C= CH₃CH₂CH₂(C=O)CH₃

D= CH₃CH₂(C=O)CH₂(C=O)CH₃

Select the sequence where the bold H atoms are in order of increasing acidity.

a) D, B, A

b) A, B, D

c) C, B, A

d) A, C, D

e) D, A, C

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

20. Which is the strongest acid?

a) HOBr

b) HBrO₂

c) HBrO₃

d) HBrO₄

Difficulty: Easy

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

Feedback: Strength of oxoacid increases as electron density is withdrawn from the OH bond.

21. Which of the following salt solutions will be the most basic?

a) 0.5 M NaNO₃

b) 0.5 M NaNO₂

c) 0.75 M NaClO₂

d) 0.75 M NaClO₄

e) 0.5 M NH₄Cl

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

Feedback: a) neutral, salt of anion of a strong acid; b) most basic, K_b = 1.8 x 10¹¹; c) K_b = 9.1 x 10^-13; d) neutral, salt of anion of a strong acid; e) acidic salt

22. In the reaction between methyl amine, H₂N(CH₃) and acetic acid, CH₃CO₂H, the conjugate acid and base produced are

a) H⁺ and OH^-.

b) H₂N(CH₃) and CH₃CO₂H.

c) H₃N(CH₃)⁺ and CH₃CO₂^-.

d) H₃N(CH₃)⁺ and OH^-.

e) H⁺ and CH₃CO₂^-.

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

23. When 0.10 moles of HCl are added to 1 L of solution containing 0.12 moles of aqueous Na₂CO₃, the major species present are

a) Na⁺, Cl^-, H₂O, HCO₃^-.

b) Na⁺, Cl^-, H₂O, CO₃^2-.

c) Na⁺, Cl^-, H₂O, HCO₃^-, CO₃^2- .

d) HCl, Na⁺, CO₃^2-.

e) Na⁺, Cl^-, H₂O, H₂CO₃, CO₃².

Difficulty: Hard

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

24. Solid NaClO is added to water. What are the major species present?

a) NaClO, HClO and water

b) Na⁺, Cl^-, O₂ and water

c) Na⁺, Cl₂, O^2- and water

d) Na⁺, ClO^- and water

e) NaClO, Na⁺, ClO^-, water

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

25. What is the pH of a 0.01 M solution of sulphuric acid?

a) 2

b) 1.70

c) 1.85

d) 1.46

e) 12

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

Feedback: a) neglects H₃O⁺ due to dissociation of second proton; b) assumes complete dissociation of both protons; c) correct answer; d) incorrect signs on solving quadratic; e) basic pH

26. Using the following table, which aqueous 1.0 M solution will have the lowest pH?

a) Na₂CO₃

b) NaHS

c) NaC₂H₃O₂

d) NaBr

e) Na₃PO₄

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

ESSAY QUESTIONS

27. What are the hydronium and hydroxide ion concentrations in a solution of 9.0 M HCl?

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

28. If 250 ml of 9.0 M HCl is diluted with 75 ml of water, what is the hydroxide ion concentration of the resulting solution?

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

29. What are the hydronium and hydroxide ion concentrations in a solution of 1.00 x10-5 M Ca(OH)₂?

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

30. What are the hydronium and hydroxide ion concentrations in a solution of 6.4 M NaOH?

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

31. At 99°C, the hydronium concentration of pure water is 9.4 x 10^-7. Is the solution neutral, acidic, or basic?

Difficulty: Medium

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

32. A 245.0 mL sample of 0.15 M Ba(OH)₂ is added to 438 mL of 0.2 M HNO₃. What is the
[OH^-] of the resulting solution?

Difficulty: Medium

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

33. Give the formulas for the six strong acids.

Difficulty: Easy

Learning Objective: Use the Brønsted–Lowry theory of acids and bases.

Section Reference: 15.1 Proton Transfers in Water

34. What is the pH of an 800 mL solution prepared from 25 g of KOH and water?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

35. What is the pH of a 9 M HCl solution?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

Feedback: Although pH values commonly fall between 0 and 14, they can be greater than 14 and less than 0.

36. What is the pH of a 9 M NaOH solution?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

Feedback: Although pH values commonly fall between 0 and 14, they can be greater than 14 and less than 0.

37. What is the pH of a solution that is 1 x10^-10 M in HNO₃?

Difficulty: Medium

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

38. What is the pOH of a solution of 1.00 x10-5 M Ca(OH)₂?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

39. What is the [OH^-] of a solution whose pH is 7.41?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

40. What is the [H₃O⁺] of a solution whose pOH is 9.45?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

41. What is the [H₃O⁺] of blood whose measured pH = 7.46?

Difficulty: Easy

Learning Objective: Relate pH to concentrations of ions in solution.

Section Reference: 15.2 The pH Scale

42. A solution is made by adding 0.1000 mole of the weak acid, HF, to water, and then adding water until the volume of the solution is 1.000 L. Of the acid added, 8.5% is dissociated.

a) What is K_a?

b) What is the pH of the solution?

Difficulty: Hard

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

43. Hydroxyl amine, HONH₂, is a weak base with K_b of 8.7x10^-9. What to extent is a 1.25 molar solution ionized?

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

44. Draw a molecular picture that illustrates the reaction that makes solutions of methylamine (CH₃NH₂) basic.

Difficulty: Easy

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

45. Draw a molecular picture of the reaction that makes solutions of formic acid acidic.

Difficulty: Easy

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

46. What is the pH of a 0.600 M HNO₂ solution (K_a=5.6 x10^-4)?

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

47. What is the pH of a 0.0250M CH₃NH₂ solution (K_b = 4.35 x10^-4)?

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

48. Determine the % ionized of a 0.200 M solution of lactic acid (pK_a = 3.85).

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

49. Determine the K_a of a 0.200 M solution of lactic acid that has a pH = 2.27.

Difficulty: Medium

Learning Objective: Calculate concentrations and pH in weak acid and base solutions.

Section Reference: 15.3 Weak Acids and Bases

50. Consider the reaction of monohydrogen carbonate with nitrous acid, HNO₂. Write the equation of reaction and identify each conjugate pair of acids and bases.

Difficulty: Medium

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

51. Consider the reaction of monohydrogen carbonate with ammonia. Write the equation of reaction and identify each conjugate pair of acids and bases.

Difficulty: Medium

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

52. The conjugate acid of HS^-1 is ______ and the conjugate base of H₂O is ______.

Difficulty: Medium

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

53. What is the name for the following acids or bases?

Difficulty: Easy

Learning Objective: Recognize and name some common acids and bases.

Section Reference: 15.4 Recognizing Acids and Bases

54. Sodium formate is added to distilled water. Will the resulting solution be acidic, basic or neutral?

Difficulty: Medium

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

55. Draw a molecular picture that illustrates the reaction responsible for the alkaline nature of sodium phosphate solutions.

Difficulty: Medium

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

56. Draw a molecular picture that illustrates the reaction responsible for the acidity of solutions of the dimethylammonium ion, (CH₃)₂NH₂⁺.

Difficulty: Medium

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

57. If the K_b of IO^-(aq) is 3.1x10^-4 what is the K_a for hypoiodous acid, HIO?

Difficulty: Easy

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

Feedback: Apply K_aK_b = K_w.

58. Solid pyridinium chloride, C₅H₅NHCl,(5 g) is added to 200 ml of water. What are the major species in solution?

Difficulty: Medium

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

59. What is the pH of a solution that is prepared by the addition of 15.0 g of NaF to sufficient water to make 1.2 L of solution? (K_a = 6.3 x10^-4, pK_a = 3.20)

Difficulty: Hard

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

60. What is the pH of a 0.15 M solution of NaNO₃?

Difficulty: Hard

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

61. What is the pH of a solution of 20.0 g of NaIO₃ in sufficient water to make 988 ml of solution: K_a (Iodic acid, HIO₃ = 1.7x10^-1)?

Difficulty: Hard

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

Feedback: Must calculate K_b from K_a; initial concentration of OH^- (of 10^-7 M) is not negligible.

62. Describe what would happen to the pH of a HNO₂ solution if some KNO₂ was added and explain why.

Difficulty: Easy

Learning Objective: Calculate the pH of solutions of salts of weak acids or bases.

Section Reference: 15.5 Acidic and Basic Salts

63. Which is the strongest acid, HClO₄, H ClO₃, H ClO₂, H ClO and why?

Difficulty: Easy

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

64. Which is the strongest base, H₂PO₄^-, HPO₄^2- or PO₄^3- and why?

Difficulty: Easy

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

65. Which acid is a strong acid, HClO₄ or HBrO₄ and why?

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

66. The pK_as of the acids, HXO (X= I, Cl, Br) are (in random order) 8.69, 7.53 10.64. Which is the value for HIO?

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

67. Which of the group 16 binary hydrides would you expect to be the strongest acid?

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

68. Which is a stronger acid, Cl₃CCO₂H or CH₃CO₂H and why?

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

69. The pK_as for the carboxylic acids (CH₃CH₂CO_­2H, CH₃CO₂H, and HCO₂H) are (in random order) 3.75, 4.75, 4.87. Place the appropriate pK_a with its acid.

Difficulty: Medium

Learning Objective: Explain the factors that contribute to the strength of an acid.

Section Reference: 15.6 Factors Affecting Acid Strength

Use the following table to answer the questions 70–74.

70. Write the equilibrium reaction for K_b2 of H₃PO₄.

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

71. Write the equilibrium reaction for K_b2 of H₂CO₃.

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

72. A solution is made by dissolving 0.1 mole Na₃PO₄ in water, adding HCl and water to give 1.00 L of solution with a pH of 7.60. What is the [HPO₄^-] in this solution?

Difficulty: Hard

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

73. A solution is made by dissolving 0.1 mole Na₂HPO₄ in 1.00 L water. What is the [H₂PO₄^-] in this solution?

Difficulty: Easy

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

74. What will be the dominant phosphate species in a solution when a small amount of H₃PO₄ is added to a solution whose pH is maintained at pH = 11?

Difficulty: Medium

Learning Objective: Calculate concentrations in solutions involving multiple equilibria.

Section Reference: 15.7 Multiple Equilibria

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