5. What is the percent ionization of a 1.4 M HC 2 H 3 O 2 solution (K a = ) at 25 C? A) 0.50% B) 0.36% C) 0.30% D) 0.18% E) 2.

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1 Name: Date: 1. For which of the following equilibria does K c correspond to an acid-ionization constant, K a? A) NH 3 (aq) + H 3 O + (aq) NH 4 + (aq) + H 2 O(l) B) NH 4 + (aq) + H 2 O(l) NH 3 (aq) + H 3 O + (aq) C) NH 4 + (aq) + OH (aq) NH 3 (aq) + H 2 O(l) D) HF(aq) + OH (aq) H 2 O(l) + F (aq) E) F (aq) + H 2 O(l) HF(aq) + OH (aq) 2. For which of the following equilibria does K c correspond to the acid-ionization constant, K a, of HC 2 O 4? A) H 2 C 2 O 4 (aq) + H 2 O(l) H 3 O + (aq) + HC 2 O 4 (aq) B) HC 2 O 4 (aq) + H 2 O(l) H 2 C 2 O 4 (aq) + OH (aq) C) HC 2 O 4 (aq) + H 3 O + (aq) H 2 C 2 O 4 (aq) + H 2 O(l) D) HC 2 O 4 (aq) + H 2 O(l) H 3 O + (aq) + C 2 O 4 2 (aq) E) HC 2 O 4 (aq) + OH (aq) C 2 O 4 2 (aq) + H 2 O(l) 3. Consider the K a values for the following acids: Cyanic acid, HOCN, Formic acid, HCHO 2, Lactic acid, HC 3 H 5 O 3, Propionic acid, HC 3 H 5 O 2, Benzoic acid, HC 7 H 5 O 2, Which of the following is the strongest acid? A) cyanic acid B) formic acid C) lactic acid D) propionic acid E) benzoic acid Page 1

2 4. Rank acetic acid (HC 2 H 3 O 2 ), hydrocyanic acid (HOCN), and hydrofluoric acid (HF) in order of increasing strength. Acid K a HC 2 H 3 O HOCN HF A) HC 2 H 3 O 2 < HOCN < HF B) HOCN < HC 2 H 3 O 2 < HF C) HF < HOCN < HC 2 H 3 O 2 D) HF < HC 2 H 3 O 2 < HOCN E) HOCN < HF < HC 2 H 3 O 2 5. What is the percent ionization of a 1.4 M HC 2 H 3 O 2 solution (K a = ) at 25 C? A) 0.50% B) 0.36% C) 0.30% D) 0.18% E) 2.2% 6. A M solution of a weak monoprotic acid is 2.6% ionized at 25ºC. What is the acid-ionization constant, K a, for this acid? A) B) C) D) E) A 1.0 M solution of a weak monoprotic acid is 0.50% ionized. What is the acid-ionization constant, K a, of the weak acid? A) B) C) D) E) Page 2

3 8. What is the hydronium-ion concentration of a 0.30 M solution of HCN (K a = ) at 25ºC? A) M B) M C) M D) M E) M 9. Hypobromous acid, HOBr, has an acid-ionization constant of at 25ºC. What is the poh of a 0.62 M HOBr solution? A) 4.40 B) 3.86 C) 5.19 D) 9.60 E) What is the ph of a solution prepared by dissolving mol of chloroacetic acid, HC 2 H 2 O 2 Cl) in 1.80 L of water? For chloroacetic acid, K a = A) 1.78 B) 2.38 C) 2.32 D) E) What is the hydronium-ion concentration in a M solution of carbonic acid, H 2 CO 3? For carbonic acid, K a1 = and K a2 = A) M B) M C) M D) M E) M 12. What is the hydronium-ion concentration of a M oxalic acid, H 2 C 2 O 4, solution? For oxalic acid, K a1 = and K a2 = A) M B) M C) M D) M E) M Page 3

4 13. What is the concentration of C 2 O 2 4 in a M oxalic acid, H 2 C 2 O 4, solution? For oxalic acid, K a1 = and K a2 = A) M B) M C) M D) M E) M 14. What is the ph of a 0.47 M solution of methylamine (CH 3 NH 2, K b = ) at 25 o C? A) B) 0.33 C) 1.85 D) E) What is the poh of a 0.10 M solution of pyridine (K b = ) at 25ºC? A) B) 4.93 C) 8.85 D) 3.93 E) What is the percent ionization at equilibrium in a 0.77 M solution of dimethylamine, (CH 3 ) 2 NH (K b = ), at 25 o C? A) 77% B) 2.5% C) 2.0% D) 100% E) 0.066% 17. Which of the following equilibria best represents the hydrolysis reaction that occurs in an aqueous solution of KNO 2? A) K + (aq) + H 2 O(l) KOH(aq) + H + (aq) B) NO 2 (aq) + H 2 O(l) HNO 2 (aq) + OH (aq) C) K + (aq) + NO 2 (aq) + H 2 O(l) KOH(aq) + HNO 2 (aq) D) NO 2 (aq) + H 2 O(l) HNO 3 (aq) + 2H + (aq) E) NO 2 (aq) + H 3 O + (aq) HNO 2 (aq) + H 2 O(l) Page 4

5 18. Which of the following salts will produce a neutral solution when added to pure water? A) LiHCO 3 B) Na 2 SO 4 C) RbNO 2 D) NH 4 NO 3 E) KNO Which of the following salts will produce an acidic solution when added to pure water? A) Li 2 O B) NaBr C) KHSO 4 D) Rb 2 CO 3 E) CsNO The K a for propionic acid is What is K b for the propionate ion? A) B) C) D) E) What is the hydroxide-ion concentration in a 0.10 M solution of Na 2 CO 3? For carbonic acid, K a1 = and K a2 = (K w = ) A) M B) M C) M D) M E) M 22. What is the ph of a solution prepared by adding 2.03 g of potassium nitrite to 145 ml of water? K a of HNO 2 is A) 7.00 B) 2.08 C) 5.72 D) 8.28 E) Page 5

6 23. Which of the following substances, if added to a 0.10 M HC 2 H 3 O 2 solution, would not increase the hydronium-ion concentration? A) NaHSO 4 (s) B) 1 M HCl C) HF(l) D) Na 2 CO 3 (s) E) H 2 C 2 O 4 (s) 24. Which of the following is the most effective buffer system for a ph value of 4.45? A) H 2 CO 3 /HCO 3 (K a1 for H 2 CO 3 is ) B) HCO 2 3 /CO 3 (K a2 for H 2 CO 3 is ) C) H 2 S/HS (K a1 for H 2 S is ) D) HC 2 O 2 4 /C 2 O 4 (K a2 for H 2 C 2 O 4 is ) E) H 3 PO 4 /H 2 PO 4 (K a1 for H 3 PO 4 is ) 25. A weak acid, HF, is in solution with dissolved sodium fluoride, NaF. If HCl is added, which ion will react with the extra hydrogen ions from the HCl to keep the ph from changing? A) OH B) Na + C) F D) Na E) none of these 26. What mass of sodium hydroxide must be added to 30.0 ml of M acetic acid in order to create a buffer with a ph of 4.54? K a for acetic acid is A) g B) 0.28 g C) 0.72 g D) 25 g E) 1.0 g 27. What is the ph at the equivalence point of the titration of a strong acid with a strong base? A) 3.9 B) 4.5 C) 7.0 D) 8.2 E) none of these Page 6

7 28. The titration curve shown below represents the titration of a weak acid with a strong base. Which point represents the equivalence point? A) I B) II C) III D) IV E) V 29. A solution contains 10. mmol of H 3 PO 4 and 5.0 mmol of NaH 2 PO 4. How many milliliters of 0.10 M NaOH must be added to reach the second equivalence point of the titration of the H 3 PO 4 with NaOH? A) 250 ml B) 150 ml C) ml D) 50 ml E) ml 30. A mL sample of propionic acid, HC 3 H 5 O 2, of unknown concentration was titrated with M KOH. The equivalence point was reached when ml of base had been added. What is the hydroxide-ion concentration at the equivalence point? K a for propionic acid is at 25 C. A) M B) M C) M D) M E) M Page 7

8 31. The titration curve shown below represents the titration of a weak base with a strong acid. Which point represents the equivalence point? A) I B) II C) III D) IV E) V 32. What is the hydronium-ion concentration of a solution that is formed by combining 600. ml of 0.20 M NaOH with 400. ml of 0.70 M HNO 3 at 25ºC? A) M B) 0.16 M C) 0.45 M D) M E) 0.60 M 33. Which of the following salts forms an acidic aqueous solution? A) NaCl B) NaCN C) CaCl 2 D) FeCl 3 E) NaNO 2 Page 8

9 34. What is K c at 25ºC for the following equilibrium? CH 3 NH + 3 (aq) + H 2 O(l) CH 3 NH 2 (aq) + H 3 O + (aq) K b (CH 3 NH 2 ) = at 25ºC. A) B) C) D) E) What is the solubility product expression for Ca 3 (PO 4 ) 2? A) K sp = [Ca 3 2+ ][(PO 4 3 ) 2 ] B) K sp = [Ca 2+ ][2PO 4 3 ] C) K sp = [Ca 2+ ] 3 [PO 4 3 ] 2 D) K sp = [3Ca 2+ ] 3 [2PO 4 3 ] 2 E) K sp = [Ca 3+ ] 2 [PO 4 2 ] What is the correct mathematical expression for finding the molar solubility (s) of Sn(OH) 2? A) 2s 2 = K sp B) 2s 3 = K sp C) 108s 5 = K sp D) 4s 3 = K sp E) 8s 3 = K sp 37. The hydroxide-ion concentration of a saturated solution of Cu(OH) 2 is M. What is the solubility product constant for Cu(OH) 2? A) B) C) D) E) What is the solubility (in g/l) of calcium fluoride at 25ºC? The solubility product constant for calcium fluoride is at 25ºC. A) g/l B) g/l C) g/l D) g/l E) g/l Page 9

10 39. What is the hydroxide-ion concentration of a saturated solution of Mg(OH) 2? For Mg(OH) 2, K sp = A) M B) M C) M D) M E) M 40. The insoluble salts AV, B 2 W, C 2 X 3, DY 2, and EZ 3, which were formed from the metal ions A +, B +, C 3+, D 2+, and E 3+ and the nonmetals V 1, W 2, X 2, Y 1, and Z 1, all have the same K sp value. Which salt has the highest molar solubility? A) AV B) B 2 W C) C 2 X 3 D) DY 2 E) EZ K sp for PbF 2 is If a M NaF solution is saturated with PbF 2, what is [Pb 2+ ] in solution? A) M B) M C) M D) M E) M 42. Which of Figures I IV represent(s) the result of mixing aqueous solutions of Na 2 S and NiCl 2 in which the ion product Q c > K sp for the insoluble product? (C = cation, A = anion) = C = A I II III IV A) only I B) only II C) only III D) only IV E) both I and II Page 10

11 43. Suppose ml of M Fe(NO 3 ) 3 is added to ml of M KIO 3. Which of the following statements is true? For Fe(IO 3 ) 3, K sp = A) A precipitate forms because Q c > K sp. B) A precipitate forms because Q c < K sp. C) No precipitate forms because Q c > K sp. D) No precipitate forms because Q c < K sp. E) Nothing happens. 44. What is the minimum concentration of Cd 2+ required to begin precipitating Cd(OH) 2 (s) in a solution of ph 10.19? For Cd(OH) 2, K sp = A) M B) M C) M D) M E) M 45. If 200 ml of M AgNO 3 is mixed with 200 ml of M NaI, what will occur? For AgI, K sp = A) Silver(I) iodide will precipitate. B) No precipitate will form. C) Sodium nitrate will precipitate. D) Silver(I) nitrate will precipitate. E) Sodium iodide will precipitate. 46. If 400 ml of M Ca(NO 3 ) 2 is mixed with 400 ml of M NaF, what will occur? For CaF 2, K sp = A) Calcium fluoride will precipitate. B) No precipitate will form. C) Sodium nitrate will precipitate. D) Calcium nitrate will precipitate. E) Sodium fluoride will precipitate. 47. Sodium chloride is added slowly to a solution that is M in Cu +, Ag +, and Au +. The K sp values for the chloride salts are , , and , respectively. Which compound will precipitate first? A) CuCl(s) B) AgCl(s) C) AuCl(s) D) All will precipitate at the same time. E) It cannot be determined. Page 11

12 48. Which of the following substances will increase the molar solubility of nickel(ii) phosphate in a saturated solution? A) Na 3 PO 4 B) HNO 3 C) NH 4 Cl D) (NH 4 ) 3 PO 4 E) KOH 49. Which of the following insoluble salts will dissolve upon reaction with excess ammonia? A) PbSO 4 B) BaSO 4 C) CaCO 3 D) HgS E) AgCl 50. What is the concentration of Cd 2+ in a M Cd(NO 3 ) 2 solution that is also 1.0 M NH 3? For Cd(NH 3 ) 2+ 4, K f = A) M B) M C) M D) M E) M Page 12

13 Answer Key 1. B 2. D 3. A 4. A 5. B 6. E 7. C 8. C 9. D 10. B 11. D 12. A 13. E 14. A 15. B 16. B 17. B 18. E 19. C 20. D 21. A 22. D 23. D 24. D 25. C 26. B 27. C 28. C 29. A 30. C 31. C 32. B 33. D 34. A 35. C 36. D 37. C 38. D 39. B 40. C 41. D 42. C 43. D 44. B Page 13

14 45. A 46. B 47. C 48. B 49. E 50. B Page 14