Acid Base Review Package

Acid Base Review Package 1. In which of the following eqb systems is HCO 3 acting as a BronstedLowry base? 2 a. HCO 3 H+ + CO 3 b. HCO 3 + HS 2 H 2 S + CO 3 c. HCO 3 + H 2 S H 2 CO 3 + HS d. HCO 3 + H 2 O H 3 O + 2 + CO 3 2. The dissolving of a base in water can be recognized by the formation of aqueous a. hydrogen ions b. hydroxide ions c. hydronium ions d. protonated water molecule 3. In the reaction: NH + 4 (aq) + H 2 O (l) H 3 O + (aq) + NH 3 (aq) H 2 O is acting like a: a. BL acid donating protons b. BL base donating protons c. BL acid accepting protons d. BL base accepting protons 4. Write an equation that shows HClO 2 acting like a weak acid in water 5. An aqueous solution of HPO 4 2 turns litmus paper blue. Write a balanced equation to represent the eqb between HPO 4 2 and H 2 O. 6. The hydrogen sulphite ion, HSO 3, is amphiprotic. a. Write the equation of the reaction between HSO 3 (aq) and CO 2 3 (aq) b. Write the equation for the reaction HSO 3 (aq) and HF (aq) 7. Define the term amphiprotic and give an example of a chemical species that is amphiprotic. 8. Consider the following reactions of the hydrogen carbonate ion in solution: a. F ( aq) + HCO 3 (aq) HF (aq) + CO 3 2 (aq) b. CH 3 COO(aq) + HCO 3 (aq) CH 3 COOH(aq) + H 2 CO 3 (aq) Describe the role of HCO 3 in each of these reactions and state what these reactions reveal about the nature of HCO 3 9. H 2 O is added separately to each substance in the following pairs of solute. With which pairs does H 2 O display its amphiprotic nature? a. HI and NH 3 b. NaI and NH 3 c. NaI and NaOH d. NaOH and NH 3 10. The conjugate acid of PO 4 3 is a. H 3 O + b. HPO 4 2 c. H 3 PO 4 d. H 2 PO 4

11. The conjugate base of HSe is a. Se 2 b. OH c. H 2 O d. H 2 Se 12. Consider the following eqb: CH 3 COOH + H 2 O H 3 O + + CH 3 COO Write the formulas of a conjugate acidbase pair in the above eqb 13. A student tested the electrical conductivity of two acid solutions. One of the solutions contained a strong acid, the other a weak acid. Both acid solutions gave the same conductivity. Explain how this result could have been obtained. 14. Which of the following experimental tests would distinguish a 0.10 M strong acid from a 0.10 M weak acid? a. electrical conductivity b. effect on phenolphthalein c. effect on thymolphthalein d. ability to neutralize NaOH 15. Which of the following compounds is a bse when in solution? a. HCl b. NH 3 c. NaCl d. CH 3 COOH 16. a) Define the term weak base. b) Give an example of a compound that is a weak base in aqueous solution. 17. The strongest base that exist in water is a. O 2 b. NH 3 c. NH 2 d. OH 18. When either HCl or NaOH is added to water at 25 o C, the fraction of water molecules ionized is: a. Less than in pure water b. Greater than in pure water c. Equal to that in pure water d. Always equal to 1.00 x 10 14 19. Consider the following eqb: H 2 O H + + OH If NH 3 is added to this eqb: a. no change occurs b. both [OH ] and [H + ] decrease c. [OH ] increases and [H + ] decreases d. [OH ] decreases and [H + ] increases 20. Consider the following eqb: H 2 O H + + OH H = +57 kj/mol If the temperature of the water is raised, then the value of Kw will: a. increase and the water will remain neutral b. increase and the water will become acidic c. decrease and the water will become basic d. decrease and the water will become neutral 21. At 40 o C, Kw = 3.1 x 10 14. Water at 40 o C may be described as a. acidic with [H 3 O + ] = 3.1 x 10 7 M b. acidic with [H 3 O + ] = 1.8 x 10 7 M c. neutral with [H 3 O + ] = 1.8 x 10 7 M d. neutral with [H 3 O + ] = 1.0 x 10 7 M

22. A student has a sample of water and measures the [H 3 O + ] at various temperatures giving the following data: Temp ( o C) 0 20 40 60 [H 3 O + ] 4.4 x 10 8 M 8.2 x 10 8 M 1.3 x 10 7 M 3.2 x 10 7 M This data shows that as water is heated a. the ph increases b. it becomes more acidic c. it is ionized to a greater extent d. [H 3 O + ] increases while [OH ] decreases 23. As the [H 3 O + ] in a solution increases, a. the ph increases and the poh increases b. the ph increases and the poh decreases c. the ph decreases and the poh increases d. the ph decreases and the poh decreases 24. Consider the following 1.0 M solutions: NaOH, HCl and NaCl Which of the following lists the solutions in increasing order of ph? a. NaOH, HCl, NaCl b. HCl, NaOH, NaCl c. NaOH, NaCl, HCl d. HCl, NaCl, NaOH 25. The ph of two solutions is measured as follows: Solution A ph = 2.0 Solution B ph = 6.0 The data suggests that the [H 3 O + ] in solution A is: a. 1/3 of that in solution B b. 3 times that in solution B c. 0.0001 of that in solution B d. 10,000 times that in solution B 26. Solution A is prepared with a ph of 2.50 and solution B with a ph of 5.00. How many times more acidic is solution A than solution B? Support your answer with calculations. 27. Which of the following describes the relationship between pkw, poh and ph? a. pkw = ph + poh b. poh = pkw + poh c. ph = pkw + poh d. ph = pkw + poh 28. In a solution of ph = 9.52, the [OH ] is a. 3.0 x 10 10 M b. 1.7 x 10 5 M c. 3.3 x 10 5 M d. 4.48 M 29. Calculate the ph of a solution prepared by dissolving 0.44 g Ba(OH) 2 in enough water to make 250.0 ml of solution. 30. A student is given a 0.10 M solution which is known to be either an acid or a base. Describe what test(s) the student should perform and how the results should be interpreted to decide whether the solution is an acid or a base and whether that acid or base is strong or weak. 31. A saturated solution of Zn(OH) 2 has a ph of 8.30. Calculate the value of Ksp for Zn(OH) 2

32. Which of the following 0.10 M acid solutions would be the strongest electrolyte? a. boric acid b. oxalic acid c. nitrous acid d. carbonic acid 33. a. Complete the following acid base reaction: HCO 3 + HSO 3 b. Identify a conjugate acid and based pair in the above reaction c. Predict whether reactants or products are favoured at eq b and justify your prediction. 34. Consider the following acidbase reaction: 2 H 2 PO 4 + HCO 3 HPO 4 + H 2 CO 3 2 a. HPO 4 is the stronger acid and reactants are favoured b. H 2 PO 4 is the stronger acid and products are favoured c. H 2 CO 3 is the stronger acid and reactants are favoured d. HCO 3 is the stronger acid and products are favoured. 35. A BronstedLowry acidbase equilibrium system is known to involve four chemical species. 2 Three of the species are listed below: HPO 4 H 2 PO 4 S 2 a. Write a balanced equation to represent the BL eq b system. b. Which BL acid would be present in the largest concentration? Explain. 36. Consider the following acidbase reactions and their respective eq b constants: A. H 2 TeO 4 + TeO 4 2 2HTeO 4 Keq = 1 x 10 3 B. H 2 SeO 3 + HTeO 4 H 2 TeO 4 + HSeO 3 Keq = 2 C. HTeO 4 + SeO 3 2 TeO 4 2 + HSeO 3 Keq = 40 a. Write a formula for the stronger acid in equation A b. Write the formula for the stronger acid in equation B c. List the four acids in decreasing order of strength. 37 a. Compare the ease with which the first hydrogen ion (proton) is removed from a diprotic acid in relation to the ease of removal of the second hydrogen ion. b. Use an example from the table of acids to illustrate the above situation. c. Give the reasons why the above situation occurs.

38. Calculate the ph of 0.50 M CH 3 COOH. (4 marks) 39. Calculate the concentration of CH 3 COOH solution in which the maximum [Ag + ] possible without a precipitate forming is 0.79 M. (4 marks) 40. Dimethylamine, HN(CH 3 ) 2, is a weak base and established the following eqb in water: HN(CH 3 ) 2 (aq) + H 2 O (l) H 2 N(CH 3 0 2 ) + (aq) + OH A 0.100 M solution of HN(CH 3 ) 2 is found to have a ph of 11.86. Calculate the value of K b for dimethylamine (4 marks) 41. The value of Kb for F is: a. 1.5 x 10 11 b. 6.7 x 10 4 c. 1.5 x 10 3 d. 1.5 x 10 3 42. An environmental chemist measures the ph and the [NH 3 ] in a river contaminated with ammonia. The collected data are : ph 10.98 [NH 3 ] 4.5 x 10 3 M Temperature 5 o C Kw @ 5 C 2.10 x 10 15 Use this data to calculate the value of K b of NH 3 at 5 o C (5 marks) 43. 1.50 g of NaOH is added to 2.0 L of 0.0150 M HCl. Assuming negligible volume change, calculate the resulting ph of the solution. (4 marks) 44. A 25.0 ml sample of Ba(OH) 2 (aq) is titrated with 0.50 M HCl. The following data were obtained: Trial Volume HCl (ml) 1 8.73 2 8.51 3 8.53 Calculate the [Ba(OH) 2 ]. (4 marks) 45. Consider the following data: Flask number Contents 1 25.00 ml 0.10 M HCl 2 25.00 ml 0.10 M CH 3 COOH 3 25.00 ml 0.10 M H 2 C 2 O 4 4 25.00 ml 0.15 M HNO 3 The flask that would require the largest volume of 0.11 M NaOH for complete neutralization in a titration is: a. 1 b. 2 c. 3 d. 4

46. Calculate the volume of 0.100 M NaOH that must be added to 0.500 L of HCl (aq) which is at a ph of 1.000 in order to produce a solution of ph = 2.000 (5 marks). 47. A student uses several indicators to determine the ph of a solution and obtain the following data: Indicator: thymol blue methyl orange methyl red phenol red phenolphthalein Colour: yellow yellow red yellow colourless The ph of the solution is: a. 2.8 b. 4.6 c. 6.3 d. 8.1 48. A solution is known to be buffered at one the following ph s: 4.0, 6.0 or 8.0. Describe how a chemist could determine the ph of solution A using the indicators methyl red and bromthymol blue. Interpret all possible results (3 marks) 49. 25.00 ml of a solution of HCl was titrated with 0.4500 M NaOH using bromthymol blue as indicator. Successive readings of the burette gave the following data: Volume NaOH (ml) Colour 16.35 yellow 16.40 yellow 16.45 green 16.50 blue Based on this data, the original [HCl] was: a. 0.2970 M b. 0.2943 M c. 0.2952 M d. 0.2961 M 50. The indicator HIn ionizes according to the following equation: HIn + H 2 O H 3 O + + In Ka = 1 x 10 4 At the transition point of HIn, which relationship is true: a. [In ] = [OH ] b. [HIn] = [In ] c. [HIn] = [H 3 O + ] d. [H 3 O + ] = [OH ] 51. An indicator, HInd, is found to establish the following equilibrium: HInd H + + Ind When the indicator was added to buffer solutions of various ph values, the following data was collected: Buffer ph 2 4 6 8 10 12 Indicator colour yellow yellow yellow yellow green blue At ph 10, a. [H + ] = Ka b. [H + ] = ph c. [H + ] = [Ind ] d. [H + ] = [Hind]

52. The approximate Ka value for the indicator thymolphthalein is: a. 1 x 10 10 b. 1 x10 4 c. 4 d. 10 53. Describe how a person should distinguish experimentally between 0.10 M weak acid solution and a 0.10 M strong acid solution. Explain how the experimental results would enable the scientist to make the distinction. (2 marks) 54. The ph of a 0.1 M Na 2 SO 3 solution is approximately a. 1 b. 7 c. 10 d. 14 55. Is a solution of NH 4 CN acidic or basic? Support your answer by writing appropriate hydrolysis equations and using the respective Ka and Kb values. 56. HPO 2 4 in water will act as a. a base since its Kb < its Ka b. as base since its Kb > its Ka c. an acid since its Kb < its Ka d. an acid since its Kb > its Ka 57. In which of the following 0.10 M solutions would Ag(OH) (s) have the lowest solubility? a. Na 2 O b. HClO 4 c. NaNO 3 d. NaCH 3 COO 58. Which of the following solutions has the highest ph? a. 0.10 M acetic acid, CH 3 COOH b. 0.10 M sodium hydroxide, NaOH c. 0.10 M ammonia, NH 3 d. 0.10 M sodium acetate, NaCH 3 COO 59. Which of the following oxides, dissolved in water, makes the most basic solution? a. SO 2 b. CO 2 c. BaO d. ClO 60. An aqueous solution of which one of the following would cause methyl red to be red in colour? a. CaO b. ZnO c. NO 2 d. Li 2 O 61. When Na 2 O (s) is dissolved in water, it will act as a a. weak acid b. weak base c. strong acid d. strong base 62. Buffers can be prepared from any a. salt and acid b. weak base and a weak acid c. weak acid and its conjugate base d. strong acid and its conjugate base 63. Which pair of solutions could be used to prepare a buffer? a. 0.25 M HCl and 0.25 M NaOH b. 0.50 M K 2 CO 3 and 0.50 M KOH c. 1.0 M NaHSO 4 and 1.0 M H 2 SO 4 d. 0.10 M HCOOH and NaHCOO 64. Which of the following chemical species, when added to 1.0 M CH3COOH, would produce a buffer? a. HCl b. H 2 O c. H 3 O + d. KCH 3 COO 65. Using KF as one of the reagents, describe how to prepare a buffer solution. Write the equation of the eqb present in this buffer and state the purpose of a buffer solution. (3 marks)

66. When 10 ml of 0.10 M Sr(OH) 2 is added to 20 ml of a solution of 0.10 M CH 3 COOH and 0.10 M NaCH 3 COO, the ph greatly increases. This result occurs because a. the solution is a buffer b. Sr(OH) 2 is a strong base c. Sr(OH) 2 contains a common ion d. amount of OH exceeds the buffer s capacity 67. Which of the following materials could be used as a primary standard for acidbase titrations? a. HCl b. NaCl c. NaOH d. KHC 8 H 4 O 4 68. List three descriptive characteristics of a primary standard used for an acidbase titration and give an example of a primary standard. 69. Consider the following eqb systems: Bromthymol blue Hind H + + In Ka = 1 x 10 7 Acetic acid CH 3 COOH H + + CH 3 COO Ka = 1.8 x 10 5 With reference to the above eqb, explain why bromthymol blue is useful as an acidbase indicator, but acetic acid is not. 70. Explain why methyl red would be a good choice for use in a titration of 0.25 M NaOH with 0.25 M HNO 3, but a poor choice for use in a titration of 0.25 M NaOH with 0.25 M HCN. (3 marks) 71. Which titration curve illustrates the titration of CH 3 COOH (aq) and KOH (aq)?

72. In a titration, which of the following combinations would result in a equivalence point with ph greater than 7.0? a. HCl and NaOH b. HNO 3 and NH 3 c. HBr and NaCH 3 COO d. CH 3 COOH and NaOH 73. Consider the following titration curves. One is of 25 ml of 0.10 M HBr titrated by 0.1 M NaOH, and the other is of 25 ml 0.1 M CH 3 COOH titrated by 0.1 M NaOH. (3 marks) a. Which curve corresponds to the titration of HBr by NaOH? b. Explain why the ph of the equivalence point is higher for graph A. Include equation(s) to support your answer. 74. If 0.10 M HNO 2 is titrated with 0.10 M NaOH, the equivalence point will have a ph a. equal to 7 since HNO 2 is a weak acid and NaOH is a weak base b. less than 7 since HNO 2 is a weak acid and NaOH is a strong base c. equal to 7 since HNO 2 is a strong acid and NaOH is a strong base d. greater than 7 since HNO 2 is a weak acid and NaOH is a strong base. 75. Which of the following indicators should be used when titrating a weak acid with a strong base? a. methyl violet b. methyl orange c. phenolphthalein d. indigo carmine 76. A suitable indicator for the titration of 0.10 M Na 2 S with 0.10 M HCl would be a. methyl violet b. methyl orange c. phenolphthalein d. thymolphthalein 77. When titrating a 25.00 ml sample of NH 3 (approximately 0.10 M), which of the following solutions should be used to determine the [NH 3 ]? a. 0.00100 M HCl b. 0.125 M HCl c. 6.00 M HCl d. 12.0 M HCl

78. Examine the following titration curve obtained from the data for the titration of 20.00 ml of the weak base B with 0.500 M HCl. Calculate the value of Kb for B using the information provided by the above graph. (6 marks) 79. Normal rain water, free from industrial pollutants, has a ph of approximately 6.4 as a result of dissolved a) H 2 (g) b) O 2 (g) c) H 2 O (g) d) CO 2 (g) 80. The Rocky Mountains consist largely of calcium carbonate. The ph of lakes and rivers in the Rockies does not change much even when exposed to acid rain. Suggest why this might be so. (1 mark)