X212F Which of the following is a weak base in aqueous solution? A) H 2 CO 3 B) B(OH) 3 C) N 2 H 4 D) LiOH E) Ba(OH) 2

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1 PX212SP14 Practice Exam II / Spring Which of the following statements are characteristic of acids? 1. They are proton donors. 2. They react with bases to produce a salt and water. 3. They taste sour. A) 1 only B) 2 only C) 3 only D) 1 and 2 only E) 1, 2, and 3 2. The major substances besides water in an aqueous solution of perchloric acid is (are) A) HClO 4 (aq). B) H + (aq) and HClO 4 (aq). C) H + (aq) and ClO 4 - (aq). D) H + (aq), HClO 4 (aq), and ClO 4 - (aq). E) HClO 4 (aq) and ClO 4 - (aq). 3. Which of the following is a weak base in aqueous solution? A) H 2 CO 3 B) B(OH) 3 C) N 2 H 4 D) LiOH E) Ba(OH) 2 4. Which of the following is a weak acid in aqueous solution? A) HNO 3 B) HCl C) H 2 SO 4 D) H 2 SO 3 E) HClO 4 Page 1

2 5. The net ionic equation for the neutralization of citric acid by a base is H 3 C 6 H 5 O 6 (aq) + 3OH (aq) 3H 2 O(l) + C 6 H 5 O 6 3 (aq) From this equation we can conclude that 1. citric acid is a weak acid. 2. the base is a strong base. 3. citric acid is the spectator ion. A) 1 only B) 2 only C) 3 only D) 1 and 2 only E) 1, 2, and 3 6. In the reversible reaction CH 3 COO - (aq) + H 2 O(l) which are the Brønsted bases? A) CH 3 COO - and CH 3 COOH B) CH 3 COO - and OH - C) H 2 O and OH - D) H 2 O and CH 3 COOH E) H 2 O, CH 3 COOH, and OH - CH 3 COOH(aq) + OH - (aq) 7. What is the net ionic equation for the acid base reaction that occurs when acetic acid and sodium hydroxide solutions are mixed? A) H + + OH - H 2 O B) H 3 O + + OH - 2H 2 O C) HC 2 H 3 O 2 + NaOH NaC 2 H 3 O 2 + H 2 O D) C 2 H 3 O H + + Na + + OH - Na + + C 2 H 3 O H 2 O E) HC 2 H 3 O 2 + OH - C 2 H 3 O H 2 O 8. Hydrochloric acid and perchloric acid appear to be equally strong acids in water, mainly because both A) react completely with water. B) form soluble salts with strong bases. C) are monoprotic acids. D) are very soluble in water. E) can participate in oxidation reduction reactions. Page 2

3 9. The acid strength decreases in the series HBr > HSO 4 > CH 3 COOH > HCN > HCO 3. The strongest base is A) CO 3 2. B) CN. C) CH 3 COO. D) SO 4 2. E) Br. 10. Which solution would cause blue litmus to turn red? A) A solution of ph 10. B) A solution of poh 4. C) A solution of 0.10 M NH 4 CH 3 COO. D) A solution of 0.01 M NH 3. E) A solution of M CH 3 COOH. 11. A solution has a hydroxide-ion concentration of M. What is the poh of the solution? A) 2.3 B) 7.0 C) 11.7 D) 5.3 E) A solution has a ph of 10.6 at 25ºC. What is its [OH - ] at 25ºC? A) M B) M C) M D) M E) 3.4 M 13. A solution has a poh of What is its hydroxide-ion concentration? A) M B) M C) M D) M E) 5.2 M Page 3

4 14. The hydronium-ion concentration of a M acetic acid solution is M. What is the ph of the solution? (K a = 1.8 x 10-5 ) A) 8.82 B) 3.00 C) 3.83 D) 4.93 E) The poh of a solution is What is its hydroxide-ion concentration? A) 5.1 M B) M C) M D) M E) M 16. A solution that is formed by combining 700. ml of 0.19 M HCl with 300. ml of 0.51 M NaOH at 25ºC has an H 3 O + concentration of A) 0.32 M. B) 0.19 M. C) M. D) 0.13 M. E) M. 17. The ph of a 0.10 M salt solution is 5.3 at 25ºC. The hydroxide-ion concentration of this solution is A) M. B) M. C) M. D) M. E) none of these. 18. The ionization constant of water at a temperature above 25 C is 2.2 x What is the ph of pure water at this temperature? H 2 O H + (aq) + OH - (aq) A) B) 6.83 C) 7.00 D) 7.83 E) 5.63 Page 4

5 19. Calculate the ph of a M Ba(OH) 2 solution. A) 2.10 B) C) 2.40 D) 9.17 E) When equal moles are dissolved in water, the hydride of which element shown below will form a solution with the highest ph? A) F B) Cl C) Br D) I E) At 21. 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) Cyanate ion B) Formic acid C) Lactic acid D) Propionic acid E) Benzoic acid Page 5

6 22. A 0.10 M aqueous solution of an acid HX has a ph of What is the value of K a for HX? A) B) C) D) E) A M aqueous solution of a weak acid HX has a ph of 4. What is the percentage dissociation of HX in the solution? A) 0.001% B) 0.1% C) 0.01% D) 1% E) 10% 24. A weak monoprotic acid is 0.60% ionized in a 1.0 M solution. The dissociation constant of the weak acid is A) B) C) D) E) Hypobromous acid, HOBr, has an acid dissociation constant of at 25ºC. Calculate the value of H 3 O + in a 0.59 M HOBr solution. A) M B) M C) M D) M E) M 26. In a 0.01 M solution of 1,4-butanedicarboxylic acid, HOOCCH 2 CH 2 COOH (K 1 = , K 2 = ), the species present in the LOWEST concentration is A) H 3 O + (aq). B) HOOCCH 2 CH 2 COOH(aq). C) HOOCCH 2 CH 2 COO (aq). D) OOCCH 2 CH 2 COO (aq). E) OH (aq). Page 6

7 27. Which of the following processes would be expected to have a S value very close to zero? A) H 2 O(s) H 2 O(l) B) 2H 2 (g) + O 2 (g) 2H 2 O(g) C) H 2 O(s) H 2 O(g) D) N 2 (g) + O 2 (g) 2NO(g) E) OF 2 (g) + H 2 O(g) O 2 (g) + 2HF(g) 28. Carbonic acid is a diprotic acid, H 2 CO 3, with K a1 = and K a2 = The ion product for water is K w = What is the carbonate-ion, CO 3 2, concentration in a M carbonic acid solution? A) B) C) D) E) What is the equilibrium constant for the reaction at 25ºC C 6 H 5 NH H 2 O C 6 H 5 NH 2 (aq) + H 3 O + (aq) K b (C 6 H 5 NH 2 ) = at 25ºC. A) B) C) D) E) What is the ph of a solution which is M in HA and also M in NaA (K a = ) at 25 C? A) 6.24 B) 3.92 C) 5.08 D) 7.34 E) 8.24 Page 7

8 31. Which of the following solutions would be expected to have the highest hydroxide concentration? A) 0.10 M Na 2 SO 4 B) 0.10 M NaNO 3 C) 0.10 M NH 4 Cl D) 0.10 M NaCN E) 0.10 M NH 4 CH 3 COO 32. A mL sample of propionic acid, CH 3 CH 2 COOH, of unknown concentration was titrated with M KOH. The equivalence point was reached when ml of base had been added. The concentration of the original propionic acid is A) M. B) M. C) M. D) M. E) M. 33. Which of the following, when added to water, will not change the ph? A) NaHCO 3 B) NH 4 NO 3 C) K 2 SO 3 D) KI E) HCN Page 8

9 34. In the titration curve shown below, which point represents the ph at the equivalence point? A) I B) II C) III D) IV E) V 35. The solubility product expression for Sn(IO 3 ) 2 is K sp = A) [Sn 4+ ][2IO 2 3 ] 2. B) [Sn 4+ ][IO 3 2 ] 2. C) [Sn 2+ ][2IO - 3 ]. D) [Sn 2+ ][IO - 3 ] 2. E) [Sn 2+ ][2IO - 3 ] The K sp for AgBr is If you mix 500 ml of M AgNO 3 with 500 ml of M NaBr, then A) AgBr will precipitate. B) no precipitation will occur. C) mol of AgBr will form. D) the concentration of Ag + will be M. E) sodium bromide will precipitate. Page 9

10 37. What is the maximum Cu 2+ concentration possible in a solution that has a M sulfide-ion concentration? (K sp for CuS = ) A) B) C) D) E) Given the equilibrium constants for the following equilibria at 25 C H 2 S(aq) H + (aq) + HS (aq) K = H + (aq) + S 2 (aq) HS (aq) K = determine the equilibrium constant for the reaction H 2 S(aq) 2H + (aq) + S 2 (aq) A) B) C) D) E) K sp BaSO x BaCrO x AgBr 5 x PbCrO x PbCO x Which salt has the highest molar solubility in water? A) BaSO 4 (K sp = ) B) PbCrO 4 (K sp = ) C) AgCl (K sp = ) D) MnS (K sp = ) E) SrCO 3 (K sp = ) 40. The K sp for manganese(ii) sulfide is at 25ºC. What is the molar solubility of MnS at 25ºC? A) mol/l B) mol/l C) mol/l D) mol/l E) mol/l Page 10

11 41. What is the molar solubility of Fe(OH) 3 at 25 C (K sp = )? A) M B) M C) M D) M E) M 42. K sp for Pb 3 (PO 4 ) 2 is Two solutions are mixed, one containing Pb 2+ and the other PO If, at the instant of mixing, Pb 2+ is 10-7 M and PO 4 3- is 10-8 M, which one of the following statements is true? A) A precipitate forms because Q sp < K sp. B) A precipitate forms because Q sp > K sp. C) No precipitate forms because Q sp = K sp. D) No precipitate forms because Q sp < K sp. E) No precipitate forms because Q sp > K sp. 43. At 25 C when 1.00 g of sulfur is burned at constant pressure in an atmosphere of oxygen to give SO 2, 9.28 kj of heat energy is liberated. The H o f of SO 2 is A) kj/mol. B) kj/mol. C) kj/mol. D) kj/mol. E) kj/mol. 44. The heat of condensation of water at 373 K is 40.7 kj/mol. When 9.00 g of water vaporizes at 373 K, the value for H is A) 366 kj. B) 81.4 kj. C) 20.4 kj. D) 20.4 kj. E) 81.4 kj. Page 11

12 45. Calculate the standard enthalpy of formation of CaCO 3 (s) given CaO(s) + CO 2 (g) CaCO 3 (s) H = kj and the following information: Compound H o (kj f mol 1 ) CO 2 (g) CaO(s) A) 1207 kj B) 851 kj C) 420 kj D) +851 kj E) kj 46. Calculate U of a gas for a process in which the gas absorbs 18 J of heat and does 6 J of work by expanding. A) 12 J B) +12 J C) 24 J D) +24 J E) None of the above 47. When ammonium nitrate dissolves in water, the solution becomes cold. We can conclude the following: A) H is positive and S is positive. B) H is positive and S is negative. C) H is negative and S is negative. D) H is negative and S is positive. E) H is positive and S is zero. 48. Calculate G for the reaction C(s) + CO 2 (g) 2CO(g) G f : CO 2 = kj/mol; CO = kj/mol A) 120 kj B) +120 kj C) kj D) kj E) Cannot determine because G f has not been given for C(s). Page 12

13 49. What is the minimum temperature required for the spontaneous conversion of CCl 4 (l) to CCl 4 (g) when H is 573 kj/mol and S is 1.64 kj/(mol K)? A) 76 C B) 89 C C) 189 C D) 215 C E) 349 C 50. For the reaction 3C(s) + 4H 2 (g) C 3 H 8 (g), S = 269 J/(mol K) H = kj/mol Calculate the equilibrium constant at 25 C for the reaction above. A) 1.0 B) C) D) E) Page 13

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

15 45. A 46. B 47. A 48. B 49. A 50. B Page 15