1.     Which of the following is NOT a valid definition of an acid?     (A) An electron pair acceptor     (B) A substance ...
(A) 0.320     (B) 2.29 x 10-4     (C) 4.57 x 10-4     (D) 4.57 x 10-6What is the pOH of a 0.350 M solution of Nitric Acid?...
(A) The electronegativity of X     (B) The strength of the H-X bond     (C) The electron affinity of X    (D) The ionizati...
(C) Barium hydroxide has a low solubility in water.     (D) Barium hydroxide is actually an acid due to the high electrone...
(A) 11.3        (B) 2.69        (C) 2.38    (D) 11.6How much pyridine (C5H5N) is needed to raise the pH of 500 mL of water...
(C) 6.25     (D) 4.35Which of the following is a characteristic of a polyprotic acid?     (A) K a1 is less than K a2.     ...
(D) 14.0What is the pH of a solution of 5.00 g acetic acid, 7.00 g sodium acetate, and 2.00 g HCl in 200 mL of water?     ...
(B) 0     (C) basic     (D) 7While performing the titration of a weak acid by a strong base, Annie Oaf and Peter Fool beca...
What is the difference between the equivalence point and the endpoint of a titration?     (A) An equivalence point is the ...
ANSWERS:   1.    B   2.    A   3.    C   4.    D   5.    B   6.    A   7.    C   8.    D   9.    B   10.   A   11.   C   1...
41.   B42.   A43.   C44.   D45.   B46.   A47.   D48.   D49.   B50.   A
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Acids and bases

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Acids and bases

  1. 1. 1. Which of the following is NOT a valid definition of an acid? (A) An electron pair acceptor (B) A substance that lowers the pOH of a solution (C) A proton donor (D) A substance that produces H+ in aqueous solution 2. Which of the following is a Bronsted base? (A) Acetate ion (B) Al3+ (C) I- (D) Ammonium ion 3. One major difference between the Bronsted-Lowry and the Arrhenius definitions of acids and bases is which of the following? (A) In the Arrhenius definition, acids release protons while in the Bronsted-Lowry definition, they donate protons. (B) Arrhenius said that bases donate electron pairs whereas Bronsted and Lowry said that bases acceptprotons. (C) The solvent dependence (D) There is no difference. 4. The K a forhypochlorous acid does not contain which of the following terms? (A) H+ (B) ClO- (C) HClO (D) H2OIf the K a of sulfurous acid is 1.54 x 10-2, what is the K b of its conjugate base? (A) 1.54 x 10-12 (B) 6.49 x 10-13 (C) 1.30 x 10-12 (D) 6.17 x 10-10What is the value of K w at 333 K? (A) 9.6 x 10-14 (B) 1.0 x 10-14 (C) 2.9 x 10-15 (D) 14What is the K a of a 0.320 M solution of nitrous acid? Nitrous acid has a pK aof 3.34.
  2. 2. (A) 0.320 (B) 2.29 x 10-4 (C) 4.57 x 10-4 (D) 4.57 x 10-6What is the pOH of a 0.350 M solution of Nitric Acid? (A) 0.460 (B) 6.70 (C) 12.0 (D) 13.5What is the pK b of an acid with a K a of 6.20 x 10-4? (A) 1.60 x 10-11 (B) 10.8 (C) 3.20 x 10-11 (D) 3.20If the pOH of a solution is 6, what is the pH? (A) 8 (B) 6 (C) 106 (D) 14What is pH? (A) log [H+] (B) A measure of the basicity of a solution (C) - log [H+] (D) - log [K a]Which of the following is true? (A) pH + pK a = 14 (B) pK b + pOH = 14 (C) pH + pOH = K w (D) pK a + pK b = pK wWhich of the following has the most impact on the acidity of a halogen acid, HX?
  3. 3. (A) The electronegativity of X (B) The strength of the H-X bond (C) The electron affinity of X (D) The ionization potential of HWhich of the following contributes to an increase in pK a for an oxyacid of the type A(OH)nOm? (A) More protons bonded to oxygens (B) A more electronegative central atom, A (C) A weaker O-H bond (D) A higher formal charge on the central atom, AWhich of the following is the weakest acid? (A) HClO4 (B) HBrO3 (C) HAsO4 - (D) H3PO4What is the [H+] in a 0.1 M solution of Nitric Acid into which 0.2 moles per liter of HCl is dissolved? (A) 0.1 M (B) 0.15 M (C) 0.2 M (D) 0.3 MWhat is the pH of a solution of 0.50 moles of nitric acid and 1.0 mole of sulfuric acid dissolved into 2.0 L of water? (A) -0.18 (B) 0.12 (C) 0.24 (D) 0.75Why can we equate the [H+] and the [strong acid]? (A) We cannot if we are treat the problem rigorously, but this is a fine approximation because the K as of strongacids are greater than 1. (B) Strong acids completely dissociate in water. (C) Strong acids have such weak Acid-H bonds that they are never formed in the first place. (D) [H+] equals the [Acid] for any acid.Why is Ba(OH)2 not a strong base whereas other alkaline earth metal hydroxides are? (A) The Ba-OH bond is exceptionally strong. (B) Barium hydroxide is a strong base.
  4. 4. (C) Barium hydroxide has a low solubility in water. (D) Barium hydroxide is actually an acid due to the high electronegativity of Ba.What is the pH of a 0.520 M solution of NaOH? (A) 0.280 (B) 14.0 (C) 0.140 (D) 13.7What happens to the pH of a solution of NaOH when BaSO4 is added? (A) The pH increase. (B) The pH decreases. (C) The pH first increases then decreases. (D) The pH first decreases then increases.What is the pH of a 1.10 M solution of hydrazoic acid? HN3 has a pK a of 4.72. (A) 2.34 (B) 4.68 (C) 1.17 (D) Not enough information to solve this problemWhat is the percent dissociation of a 0.010 M solution of acetic acid? The K aof acetic acid is 1.76 x 10-5. (A) 5.0% (B) 2.1% (C) 4.2% (D) 100%What is the pH of 2 L of a 1.0 M HF solution to which 42 g of NaF are added, causing no net change in volume?The K a of HF is 6.6 x 10-4. (A) 1.59 (B) 3.18 (C) 1.06 (D) 2.88What is the pK a of a monoprotic weak acid that gives a pH of 6.2 when you prepare a 0.56 M solution of that acid? (A) 12.4 (B) 12.1 (C) 6.2 (D) 4.75What is the pH of a 0.230 M solution of NH3? The pK b of NH3 is 4.75.
  5. 5. (A) 11.3 (B) 2.69 (C) 2.38 (D) 11.6How much pyridine (C5H5N) is needed to raise the pH of 500 mL of water by 2 units? The pK a of the pyridinium ion is5.25. (A) 4.44 g (B) 6.66 g (C) 2.22 g (D) 1.11 gWhat is the pOH of a mixture of 5 g of Ba(OH)2 in 100 mL of water given its Kspis 5.0 x 10-3. (A) 0.53 (B) 1.06 (C) 2.12 (D) 1.15What is the pH of a 1.0 M solution of NaCl in water? (A) 5.5 (B) 7 (C) 8.5 (D) 0When a weak base dissolves in water to form a 1.0 M solution, it gives a pH of 9.0. What is the pK a of its conjugateacid? (A) 4.0 (B) 5.0 (C) 6.0 (D) 10.0What is the pH of a 0.25 M solution of NaOAc (sodium acetate) in water if the pK a ofAcOH (acetic acid) is 4.75? (A) 4.93 (B) 7 (C) 9.07 (D) 12.3What is the pH of a 3.60 M solution of ammonium chloride (NH4 +Cl) in water if the pK b of ammonia is 4.75? (A) 9.65 (B) 7.00
  6. 6. (C) 6.25 (D) 4.35Which of the following is a characteristic of a polyprotic acid? (A) K a1 is less than K a2. (B) Loses its protons in a stepwise manner (C) Has many protons but only one is labile (D) Is strongly acidic due to the large number of protonsWhat is the pH of a 3.0 M solution of phosphoric acid in water? pK a1 is 2.12, pK a2 is 7.21, and pK a3 is 12.67. (A) 0.82 (B) 0.75 (C) 1.0 (D) 0.92What is the pH of a 0.10 M solution of sodium hydrogensulfate? For sulfuric acid, pK a1 is -2, pK a2 is 1.92. (A) 3.46 (B) 0.46 (C) 1.46 (D) 4.46What condition must be satisfied to make a good buffer? (A) You must mix a strong acid with its conjugate base. (B) You must mix a weak acid with its conjugate base. (C) The ratio of base to acid must be around 10. (D) The ratio of base to acid must be around 1.Which of the following is the Henderson-Hasselbalch equation? (A) pK a = pH + log (base / acid) (B) pH = pK a + log (base / acid) (C) log (base / acid) =pK a / pH (D) PV = nRTWhat is the pH of an equimolar mixture of acetic acid and sodium acetate? The K a of acetic acid is 1.76 x 10-5. (A) 4.75 (B) 9.25 (C) 7.00
  7. 7. (D) 14.0What is the pH of a solution of 5.00 g acetic acid, 7.00 g sodium acetate, and 2.00 g HCl in 200 mL of water? (A) 4.75 (B) 7.00 (C) 4.10 (D) 0.56If the pH of a solution you wish to control using a buffer is 8.0, which of the following buffer compositions would youprefer? (A) HOAc / AcO- (B) HCl / Cl- (C) H3PO4 / H2PO4 - (D) NH3 / NH4 +On a titration curve, at what point does the titrant exactly neutralize the unknown? (A) Endpoint (B) Equivalence point (C) pH = pK a of the indicator (D) pH = pK a of the weak acidHow much HCl should be added to 500 mL of a 1.0 M NaOH solution achieve the highest pH on a titration curve? (A) 0 moles (B) 0.5 moles (C) 1 mole (D) 10 molesWhich of the following is required to measure the pH of the unknown solution during a titration? (A) An accurate indicator (B) pH paper (C) The volume and concentration of titrant needed for neutralization (D) A pH meterWhat is the pH at the equivalence point for a titration of a strong acid by a strong base? (A) 14
  8. 8. (B) 0 (C) basic (D) 7While performing the titration of a weak acid by a strong base, Annie Oaf and Peter Fool became discouraged whenthey reached a pH of 4 and noticed that it takes a large amount of base to change the pH significantly. They figuredthat they had "messed up" and needed to start over. What feature of the titration curve fooled them? (A) The slow transition region from acidic to basic around the equivalence point (B) The buffering region (C) The sharp change in pH near the equivalence point (D) They forgot to standardize their base.What will be the pH at the equivalence point for a weak base being titrated with a strong acid? (A) Acidic (B) Basic (C) 7 (D) Not enough information to solve this problemWhat is the molecular weight of a weak acid solution (5.0 g in 100 mL) that is neutralized by 50 mL of a 1.0 M NaOHsolution? (A) 100 (B) 250 (C) 50 (D) Not enough information given to solve this problemWhat volume of 1.016 M NaOH is required to completely titrate 45.00 mL of a 0.6532 M H2SO4 solution? (A) 28.93 mL (B) 36.42 mL (C) 86.31 mL (D) 57.86 mLWhat property of an indicator is essential for its function? (A) Its pK a is almost exactly the pH of the equivalence point (B) Its acidic and basic forms are differently colored (C) It is inexpensive to use (D) It is "environmentally friendly"
  9. 9. What is the difference between the equivalence point and the endpoint of a titration? (A) An equivalence point is the volume of titrant at which the amount of acid equals the amount of base whereasthe endpoint is the volume of titrant at which you stop your titration (the solution is quenched by the titrant). (B) The equivalence point is the volume of titrant at which you stop your titration whereas the endpoint is thevolume of titrant at which you should end your titration. (C) The equivalence point has to do with the electrochemical potential of the two solutions whereas the endpointis the titrant volume at which you end your titration. (D) There is no difference, they are synonymous.
  10. 10. ANSWERS: 1. B 2. A 3. C 4. D 5. B 6. A 7. C 8. D 9. B 10. A 11. C 12. D 13. B 14. A 15. C 16. D 17. B 18. A 19. C 20. D 21. B 22. A 23. C 24. D 25. B 26. A 27. C 28. D 29. B 30. A 31. C 32. D 33. B 34. A 35. C 36. D 37. B 38. A 39. C 40. D
  11. 11. 41. B42. A43. C44. D45. B46. A47. D48. D49. B50. A

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