Answers to UNIT 10 Self Test:

Part 1: Matching

1.  b    2. bc    3. ae    4. ac    5. c    6. d    7. ab    8. e    9. a    10. ad

11. a; Only one of these hydrogens will ionize.

12. d; "strong" refers to 100% dissociation or ionization.

13. d; 12.0 M is concentrated and the fact that the acid 100% ionizes means that it is also strong.

14. a; acetic acid is a weak acid that partially dissociates and has a Ka, and NaOH is a strong base, dissociating completely.

15. b; H₂O accepts a proton from NH₄⁺ to become H₃O⁺.

16. d; Since Ka for formic acid is larger that means it ionizes more, therefore it produces more H₃O⁺ and HCO₂^- in solution.

17. a; acid turns blue litmus to red.

18. b; If [OH^-] = 1 x 10^-5 M then [H₃O⁺] = 1 x 10^-9 M, thus [OH^-] > [H₃O⁺], a basic solution.

19. a; these are the products of the self ionization of water that leads to the relationship between [OH^-] & [H₃O⁺].

20. a; in this case [OH^-] = 1 x 10^-3 M.

21. b; -log (0.0010) = 3.00

22. c; Weak acids and their conjugate bases in similar proportions make good buffers.

23. d

24. b; At the equivalence point, a weak base completely reacts with the strong acid leaving only the weak conjugate acid.  This produces a small amount of H₃O⁺ dropping the pH below 7.

Part II: Problems

25.  a)  Ka = [H₂PO₄^-][H₃O⁺]                    b)  Ka = [NH₃][H₃O⁺]
                            [H₃PO₄]                                               [NH₄⁺]

26. a.         H₃PO₄   +  Al(OH)₃     à  AlPO₄  +  3H₂O

b.         HI  +  Ca(OH)₂    à  CaI₂  +  2H₂O

c.         H₂SO₄   +  2 NH₃   à (NH₄)₂SO₄

d.         3 HCl   +  Al(OH)₃     à 3H₂O  +  AlCl₃

27.           Acid                Base          Conjugate Acid      Conjugate Base

            (a) H₂CO₃               H₂O                H₃O⁺                    HCO₃^-

            (b) HCl                   H₂O                H₃O⁺                    Cl^-

            (c) H₂O             CH₃COO^-        CH₃COOH            OH^-

28.  (a) pH = 9.00, basic    (b) pH = 4.422, acidic    (c) pH = 2.82, acidic    (d) pH = 12.65, basic

29. (a) pH > 7    (b) pH = 7    (c) pH < 7    (d) pH > 7
      (e) PO₄^3- + H₂O à HPO₄^2- + OH^-

30. (a) 1 x 10^-5 M    (b) 5.8 x 10^-5 M    (c) 0.19 M    (d) 0.1 M

32.  Ka = 5.2 x 10^-5

33. Ka = 5.4 x 10^-3

34. acid added:  CH₃COO^-  +  H₃O⁺ à  CH₃COOH  + H₂O
      base added: CH₃COOH  +  OH^- à  CH₃COO^-  +  H₂O

35. (a) NT    (b) NT    (c) AT    (d) NT

36. Volume of HNO₃ = 140 mL