1. For the following reaction of benzoic acid (HOBz) with water,
   HOBz + H₂O <==> H₃O⁺ + OBz^-

   which of the following statements is correct?

   1. HOBz and H₃O⁺ are a conjugate acid/base pair.
   2. HOBz and OBz^- are a conjugate acid/base pair.
   3. HOBz and H₂O are a conjugate acid/base pair.
   4. H₂O and OBz^- are a conjugate acid/base pair.
   5. H₂O and H₃O⁺ are the only conjugate acid/base pair in the reaction.

2. What is the pH of a solution that contains 2.5 x 10^-5 M hydronium ion?

3. What is the molar concentration of hydroxide ion, [OH^-], in a water solution that contains 2.5 x 10^-4 hydronium ion (H₃O⁺)?

4. What is the molar hydroxide ion concentration, [OH^-], in a solution with pH = 7.63?

5. For the following reaction of acetic acid (HOAc) with water,
   HOAc + H₂O <==> H₃O⁺ + OAc^-

   which of the following statements is correct?

   1. HOAc and H₃O⁺ are a conjugate acid/base pair.
   2. HOAc and H₂O are a conjugate acid/base pair.
   3. H₂O and OAc^- are a conjugate acid/base pair.
   4. HOAc and OAc^- are a conjugate acid/base pair.

6. Calculate the pH of a 0.042 M solution of hydrobromic acid (HBr).

7. If we gradually increase the concentration of a strong acid in water without changing the volume significantly, then the:
   1. concentrations of hydronium and hydroxide ion will both increase.
   2. concentrations of hydronium and hydroxide ion will both decrease.
   3. hydronium ion concentration will decrease and the hydroxide ion concentration will increase.
   4. hydronium ion concentration will increase and the hydroxide ion concentration will decrease.
   5. concentrations of hydronium and hydroxide ion will be unaffected.

8. Which of the following is the conjugate base of H₂PO₄^- ?
   1. H₃PO₄
   2. HPO₄^-
   3. HPO₄^2-
   4. PO₄^3-
   5. PO₄^2-

9. The scale on the pH meter used in the laboratory ranges from pH = 0 to pH = 14. The range of hydronium ion concentrations represented by this scale is:
   1. 14 fold.
   2. 1 x 10⁷ fold.
   3. 1 x 10^-7 fold.
   4. 1 x 10¹⁴ fold.
   5. none of the above is correct.

10. Which of the following is NOT a Bronsted-type acid-base reaction?
    1. NH₃ (aq) + H₃O⁺ (aq) <=> NH₄⁺ (aq) + H₂O (l)
    2. OH^- (aq) + HNO₃ (aq) <=> H₂O (l) + NO₃^- (aq)
    3. HSO₄^- (aq) + NH₃ (aq) <=> NH₄⁺ (aq) + SO₄^2- (aq)
    4. Zn (s) + 2 HCl (aq) <=> Zn²⁺ (aq) + H₂ (g) + 2 Cl^- (aq)
    5. 2 H₂O (l) <=> H₃O⁺ (aq) + OH^- (aq)

11. If it takes 1.0 gram of solid NaOH (a strong base) to change the pH of a solution containing a strong acid from 1 to 2, how much solid NaOH (in g) would be needed to change the pH of this solution from 2 to 3? You may assume that there is no change in the volume of the solution.

12. What is the hydroxide ion concentration in a 1.0 x 10^-4 M solution of HCl?

13. Consider a solution that is prepared by dissolving 2.6 g of hydrogen iodide (HI, MW=127.9 g/mol) in enough pure water to make 1.0 L of solution. Calculate:
    1. the total hydronium ion concentration (i.e., [H₃O⁺]_total).

    2. the pH of the solution.

    3. the total hydroxide ion concentration (i.e., [OH^-]_total).

    4. the hydroxide ion concentration that results from the dissociation of water (i.e., [OH^-]_water).

    5. the pOH.

14. Calculate the pH and pOH in a solution that contains a hydronium ion (H₃O⁺) concentration of 2.3 x 10^-4 M.
    1. pH = 3.64, pOH = 3.64
    2. pH = 10.36, pOH = 3.64
    3. pH = 4.0, pOH = 10.0
    4. pH = 3.64, pOH = 10.36
    5. pH = 7.00, pOH = 7.00

15. Why is it necessary to take the acid-base properties of water into account when computing the hydronium ion concentration of very dilute solutions of strong acids?
    1. The hydroxide ion produced from the dissociation of water reacts with most of the hydronium ion produced from the acid.
    2. The dissociation constant for water is larger in dilute rather than in concentrated solutions of acids.
    3. The acids do not dissociate completely in dilute solutions.
    4. The amount of hydronium ion produced by the dissociation of water is significant compared to that produced by the acid.
    5. The conjugate base of the strong acid reacts with the hydroxide ion produced from the dissociation of water.

16. Calculate the pH of a solution prepared by dissolving 5.9 x 10^-5 moles of HCl in 1.0 L of pure water.
    1. 3.77
    2. 4.77
    3. 4.23
    4. 10.23
    5. none of these are correct to within 5% because dissociation of water must be taken into account.

17. What is the hydroxide concentration in a solution with pH = 5.14?
    1. 1.0 x 10^-14
    2. 1.4 x 10^-2
    3. 1.4 x 10^-9
    4. 7.2 x 10^-6
    5. 5.2 x 10^-9

18. Given this equilibrium reaction,
    NH₃ + H₂O <==> NH₄⁺ + OH^-

    According to Bronsted-Lowry theory, which species are considered acids?

    1. Both NH₃ and OH^-
    2. Both NH₃ and NH₄⁺
    3. Both H₂O and NH₃
    4. Both H₂O and OH^-
    5. Both H₂O and NH₄⁺

19. Which of the following reactions is not considered an acid/base reaction?
    1. 2HCl + Mg --> MgCl₂ + H₂
    2. 2HCl + Mg(OH)₂ --> MgCl₂ + 2H₂O
    3. 2HCl + MgO --> MgCl₂ + H₂O
    4. HCl + H₂O --> H₃O⁺ + Cl^-

20. The following compounds can be considered bases according to Bronsted-Lowry theory. Which compound is not a base according to Arrhenius' definition?
    1. Ca(OH)₂
    2. Na₂O
    3. H₂O
    4. RbOH

21. HPO₄^2- is a Bronsted acid. Which of the following would be the conjugate base of this acid?
    1. H₃PO₄
    2. H₂PO₄^-
    3. PO₄^3-
    4. H₃O⁺
    5. OH^-

22. How many grams of HCl (molar mass = 36.5 g/mol) are needed to make 250 mL of a strong acid solution having a pH equal to 1.00?

23. NH₂^- is a Bronsted base. Which of the following would be the conjugate acid of this base?
    1. H₂O
    2. H₃O⁺
    3. OH^-
    4. NH₃
    5. NH^2-

24. Which of the following substances is NOT an Arrhenius base?
    1. H₂O
    2. MgO
    3. NaOH
    4. Ca(OH)₂
    5. KOH

25. Which of the following reactions IS a Bronsted acid-base reaction?
    1. NaCl(s) <==> Na⁺(aq) + Cl^-(aq)
    2. 2Cu⁺(aq) <==> Cu(s) + Cu²⁺(aq)
    3. Cu²⁺(aq) + 4F^-(aq) <==> CuF₄^2-(aq)
    4. NH₃(g) + H₂O(l) <==> NH₄⁺(aq) + OH^-(aq)
    5. 2NO₂(g, nitrogen dioxide) <==> N₂O₄(g, dinitrogen tetroxide)

26. Consider the following equilibrium reaction,
    NH₃(aq) + H₂O(l) <==> NH₄⁺(aq) + OH^-(aq)

    According to Bronsted-Lowry theory, which species are considered bases?

    1. both NH₃ and NH₄⁺
    2. both NH₃ and OH^-
    3. both H₂O and NH₃
    4. both H₂O and OH^-
    5. both H₂O and NH₄⁺

27. Which of the following species is the CONJUGATE BASE of HCO₃^-?
    1. H₂CO₃
    2. HCO₃^2-
    3. H₃O⁺
    4. CO₃^2-
    5. OH^-

28. Calculate the pH of a 0.88 MOLAL solution of perchloric acid (HClO₄, a strong acid). The density of the solution is 1.05 g/mL.
    1. 0.056
    2. 0.071
    3. 0.092
    4. 0.88
    5. 1.2

29. Calculate the concentration (in M) of HCl that would be needed to make an aqueous solution of HCl with a pH of 4.3.

30. What are the products of the following Bronsted acid-base reaction?
    HCO₃^-(aq) + F^-(aq) <=> ?
    1. CO₂(g) + H₂O(l)
    2. H₂CO₃(aq) + HF(aq)
    3. CO₃^2-(aq) + HF(aq)
    4. H₃O⁺(aq) + HF(aq)
    5. F₂(g) + H₃O⁺(aq)

31. Consider the following data,

    solution	conductance (uS)
    0.0050 M HCl (hydrochloric acid, Ka = 1 x 106)	1930
    0.0050 M CH3CO2H (acetic acid, Ka = 1.8 x 10-5)	134

    The conductance of the HCl solution is greater than the conductance of the CH₃CO₂H solution because:

    1. HCl reacts with water to produce a lesser quantity of ions in solution than the reaction of CH₃CO₂H with water.
    2. HCl reacts with water to produce a greater quantity of ions in solution than the reaction of CH₃CO₂H with water.
    3. HCl is a weaker acid than CH₃CO₂H.
    4. the dissociation of water makes a more significant contribution to [H₃O⁺]_total in the HCl solution than in the CH₃CO₂H solution.
    5. the conjugate base of HCl is a stronger base than the conjugate base of CH₃CO₂H.

32. In order for a chemical substance to be able to function as a Bronsted base, the substance must contain:
    1. at least one H atom.
    2. at least one O atom.
    3. at least one N atom.
    4. at least one OH group.
    5. at least one unshared pair of electrons.

33. The concentration of NaOH (a strong base) in water is gradually increased without changing the volume significantly. Which of the following describes what happens to the concentrations of H₃O⁺ and OH^-, the pH and the pOH?

    	concentration of H3O+	concentration of OH-	pH	pOH
    (a)	increases	increases	increases	decreases
    (b)	increases	decreases	increases	decreases
    (c)	increases	decreases	decreases	increases
    (d)	decreases	decreases	decreases	increases
    (e)	decreases	increases	increases	decreases

34. Consider the following reaction,
    NH₃(aq) + H₂O(l) <==> NH₄⁺(aq) + OH^-(aq)

    Which of the following pairs IS a conjugate acid-base pair in this reaction?

    1. NH₃ ; H₂O
    2. NH₄⁺ ; OH^-
    3. NH₃ ; NH₄⁺
    4. H₂O ; NH₄⁺
    5. None of these.

35. Calculate the pH of a solution prepared by dissolving 2.13 g of NaOH (a strong base) in enough water to produce 100 mL of solution.

36. Calculate the concentration of H₃O⁺ from the dissociation of water (i.e., [H₃O⁺]_water) in the solution described in the preceding question.

37. The concentration of HNO₃ (a strong acid) in water is gradually increased without changing the volume significantly. Which of the following describes what happens to the concentrations of H₃O⁺ and OH^-, the pH and the pOH?

    	concentration of H3O+	concentration of OH-	pH	pOH
    (a)	increases	increases	increases	decreases
    (b)	increases	decreases	increases	decreases
    (c)	decreases	increases	increases	decreases
    (d)	decreases	decreases	decreases	increases
    (e)	increases	decreases	decreases	increases

38. What are the products of the following Bronsted acid-base reaction?
    HSO₄^-(aq) + S^2-(aq) <=> ?
    1. SO₃(g) + H₂O(l)
    2. H₂SO₄(aq) + S^3-(aq)
    3. SO₄^2-(aq) + HS^-(aq)
    4. H₃O⁺(aq) + H₂S(aq)
    5. H₂S(aq) + H₂O(l)

Answers

1. B
2. 4.60
3. 4.0 x 10^-11
4. 4.26 x 10^-7
5. D
6. 1.4
7. D
8. C
9. D
10. D
11. 1.0 x 10^-1
12. 1 x 10^-10
13. 1. 0.020
    2. 1.7
    3. 5.0 x 10^-13
    4. 5.0 x 10^-13
    5. 12.3

14. D
15. D
16. C
17. C
18. E
19. A
20. B
21. C
22. 0.912
23. D
24. B
25. D
26. B
27. D
28. B
29. 5.0 x 10^-5
30. C
31. B
32. E
33. E
34. C
35. 13.7
36. 1.9 x 10^-14
37. E
38. C