Chapter 18 ACID-BASE REACTIONS

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 1 Chapter 18 ACID-BASE REACTIONS 18-1. Predict the products of the following acid-base reaction: HCl(aq) + NaOH(aq)? (a) H 3 O + (aq) + OH - (aq) (b) Na + (aq) + Cl - (aq) (c) H 2 O(l) + NaCl(aq) (d) no reaction takes place 18-2. Predict the products of the following acid-base reaction: HCl(aq) + NaCH 3 COO(aq)? (a) H 2 O(l) + NaCl(aq) (b) H 2 O(l) + OH - (aq) (c) NaCl(aq) + CH 3 COOH(aq) (d) no reaction takes place 18-3. Predict the products of the following acid-base reaction: NaOH(aq) + HF(aq)? (a) NaF(aq) + H 2 O(l) (b) NaH(aq) + HOF(aq) (c) OH - (aq) + NaF(aq) (d) no reaction takes place 18-4. Predict the products of the following acid-base reaction: NH 3 (aq) + HNO 3 (aq)? (a) NH 2 OH(aq) + HNO 2 (aq) (b) NH 4 NO 3 (aq) (c) NH 4 OH(aq) (d) no reaction takes place 18-5. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, HCl(aq) + NaHCO 3 (aq)? 18-6. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, HCl(aq) + NaOH(aq)? 18-7. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, HF(aq) + KOH(aq)? 18-8. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, H 2 SO 4 (aq) + KOH(aq)?

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 2 18-9. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, CH 3 COOH(aq) + NH 3 (aq)? 18-10. The following reactants are mixed in equal molar portions. Predict if the resulting solution will be acidic, HCl(aq) + Ca(OH) 2 (aq)? 18-11. We mix 100. ml of 0.10 M HCl and 100. ml of 0.10 M NaCN. What is the ph of the resulting solution? K a (HCN) = 4.0 x 10-10 (a) 8.65 (b) 5.20 (c) 8.80 (d) 5.35 18-12. We mix 100. ml of 0.20 M HBr and 50.0 ml of 0.40 M NaClO. What is the ph of the resulting solution? K a (HClO) = 3.5 x 10-8 (a) 9.83 (b) 4.07 (c) 4.17 (d) 3.92 18-13. We mix 50.0 ml of 0.050 M HNO 3 and 25.0 ml of 0.10 M NaCH 3 COO. What is the ph of the resulting solution? K a (CH 3 COOH) = 1.8 x 10-5 (a) 3.11 (b) 3.02 (c) 2.87 (d) 10.89 18-14. We mix 55.0 ml of 0.10 M HCl and 110. ml of 0.050 M NH 3. What is the ph of the resulting solution? K a (NH 4 +) = 5.6 x 10-10 (a) 5.13 (b) 5.36 (c) 8.64 (d) 5.98 18-15. We add 1.00 ml of 10.0 M HNO 3 to 100. ml of 0.10 M NaHCOO. What is the ph of the resulting solution? K a (HCOOH) = 1.8 x 10-4 (a) 11.6 (b) 3.45 (c) 1.16 (d) 2.38 18-16. We add 100. ml of 0.10 M NaOH to 100. ml of 0.10 M HClO. What is the ph of the resulting solution? K b (ClO - ) = 2.9 x 10-7 (a) 10.3 (b) 3.76 (c) 10.1 (d) 3.91 18-17. We add 200. ml of 0.10 M KOH to 50.0 ml of 0.40 M HF. What is the ph of the resulting solution? K b (F - ) = 1.4 x 10-11 (a) 8.02 (b) 5.97 (c) 9.32 (d) 8.37

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 3 18-18. We add 100. ml of 0.50 M NaOH to 50.0 ml of 1.00 M NH 4 Cl. What is the ph of the resulting solution? K b (NH 3 ) = 1.8 x 10-5 (a) 11.6 (b) 11.4 (c) 2.61 (d) 9.34 18-19. We add 1.00 ml of 10.0 M NaOH to 50.0 ml of 0.20 M HNO 2. What is the ph of the resulting solution? K b (NO 2 -) = 2.2 x 10-11 (a) 8.32 (b) 5.68 (c) 9.17 (d) 10.3 18-20. We add 24.0 ml of 0.45 M NaOH to 20.0 ml of 0.54 M HCN. What is the ph of the resulting solution? K b (CN - ) = 2.5 x 10-5 (a) 6.83 (b) 11.6 (c) 10.8 (d) 11.4 18-21. We have a solution of NH 3. What effect will addition of HCl have on the ph of the solution? 18-22. We have a solution of NH 4 Cl. What effect will addition of NH 3 have on the ph of the solution? 18-23. We have a solution of acetic acid. What effect will addition of sodium acetate have on the ph of the solution? 18-24. We have a solution of NH 4 Cl. What effect will addition of NaCl have on the ph of the solution? 18-25. We have 100. ml of a 0.10 M solution of CH 3 COOH. It has a ph = 2.9. If we add 0.820 g of NaCH 3 COO what will the ph be? (K a (CH 3 COOH) = 1.8 x 10-5 ) (a) 2.9 (b) 1.8 (c) 3.7 (d) 4.7 18-26. We have 250. ml of a 0.20 M solution of NH 4 Cl. It has a ph = 4.97. If we add 10.0 ml of a 1.00 M NH 3 solution, what will the ph be? K a (NH 4 +) = 5.6 x 10-10 (a) 10.0 (b) 4.3 (c) 8.6 (d) 5.7 18-27. We have 500. ml of a 0.35 M solution of HCN. It has a ph of 4.92. If we add 0.50 g of NaCN(s), what will the ph of the solution be? K a (HCN) = 4.0 x 10-10 (a) 8.2 (b) 9.4 (c) 10.6 (d) 3.7

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 4 18-28. We have 200. ml of a 0.53 M solution of NaF. We add to this solution 100. ml of a 0.20 M solution of HF. What is the ph of the resulting solution? K a (HF) = 7.2 x 10-4 (a) 3.1 (b) 3.9 (c) 2.4 (d) 7.9 18-29. We have 100. ml of water. We add to this 0.50 g of NaCH 3 COO and 1.00 ml of 1.00 M CH 3 COOH. What is the ph of the resulting solution? K a (CH 3 COOH) = 1.8 x 10-5 (a) 8.8 (b) 4.7 (c) 4.0 (d) 5.6 18-30. We have 50.0 ml of water and add to it 2.0 g of NH 4 Cl and 3.00 ml of 0.50 M NH 3. What is the ph of the resulting solution? K b (NH 3 ) = 1.8 x 10-5 (a) 9.26 (b) 4.74 (c) 7.86 (d) 5.53 18-31. We have 500. ml of a 0.10 M NH 3 solution. We add 1.0 ml of 10.0 M HCl. What is the ph of the resulting solution? K b (NH 3 ) =1.8 x 10-5 (a) 5.35 (b) 4.15 (c) 8.64 (d) 9.85 18-32. We have 100. ml of a 0.20 M NaF solution and add to it 10.0 ml of 0.50 M HCl. What is the ph of the resulting solution? K b (F - ) =1.4 x 10-11 (a) 11.4 (b) 3.6 (c) 3.1 (d) 2.7 18-33. We have 250. ml of 0.33 M NaClO. We add to this solution 50.0 ml of 0.10 M HNO 3. What is the ph of the resulting solution? K b (ClO - ) = 2.9 x 10-7 (a) 9.1 (b) 8.6 (c) 6.3 (d) 5.4 18-34. We have 50.0 ml of 0.58 M NaCN. We add to this solution 10.0 ml of 1.0 M HClO 4. What is the ph of the resulting solution? K b (CN - ) = 2.5 x 10-5 (a) 4.9 (b) 5.3 (c) 9.1 (d) 9.7 18-35. We have 100. ml of a 0.10 M HCN solution. We add to this solution 50.0 ml of 0.10 M NaOH. What is the ph of the resulting solution? K a (HCN) = 4.0 x 10-10 (a) 9.4 (b) 10.2 (c) 4.6 (d) 7.0 18-36. We have 250. ml of a 0.20 M HF solution. We add to this solution 20. ml of 0.50 M KOH. What is the ph of the resulting solution? K a (HF) = 7.2 x 10-4 (a) 10.1 (b) 12.1 (c) 2.5 (d) 3.7

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 5 18-37. We have 555 ml of a 0.37 M NH 4 Cl solution. We add to this solution 1.00 g of pure NaOH(s). What is the ph of the resulting solution? K a (NH 4 +) = 5.6 x 10-10 (a) 6.2 (b) 8.4 (c) 10.1 (d) 9.3 18-38. We have 100. ml of a 0.10 M solution of CH 3 COOH. How many grams of NaCH 3 COO must be added to make a buffer solution of ph = 5.00? K a (CH 3 COOH) = 1.8 x 10-5 (a) 0.88 (b) 24.7 (c) 0.56 (d) 1.48 18-39. We have 300. ml of a 0.20 M solution of HF. How many grams of solid KF should be added to make a buffer of ph = 3.00? K a (HF) = 7.2 x 10-4 (a) 2.51 (b) 10.8 (c) 0.45 (d) 8.45 18-40. We have 500. ml of a 0.50 M solution of HNO 2. How many grams of NaNO 2 should be added to make a buffer of ph = 4.00? K a (HNO 2 ) = 4.5 x 10-4 (a) 10.2 (b) 0.67 (c) 77.6 (d) 104.3 18-41. We have 100. ml of a 0.20 M solution of NaClO. How many milliliters of 0.10 M HClO should be added to make a buffer of ph = 7.2? K a (HClO) = 3.5 x 10-8 (a) 45.7 (b) 360 (c) 126 (d) 339 18-42. We have 250. ml of a 0.56 M solution of NaCH 3 COO. How many milliliters of a 0.50 M CH 3 COOH solution should be added to make a buffer of ph = 4.40? K a (CH 3 COOH) = 1.8 x 10-5 (a) 198 (b) 231 (c) 754 (d) 622 18-43. We have 375 ml of a 0.68 M solution of NH 3. How many grams of solid NH 4 Cl should be added to make a buffer of ph = 9.50? K a (NH 4 +) = 5.6 x 10-10 (a) 7.70 (b) 4.50 (c) 2.97 (d) 0.34 18-44. We have 100. ml of a buffer solution containing 0.10 M CH 3 COOH and 0.10 M NaCH 3 COO. If we add 5.00 ml of 0.50 M HCl to this solution, what will the resulting ph be? K a (CH 3 COOH) = 1.8 x 10-5 (a) 4.97 (b) 4.52 (c) 7.00 (d) 8.48 18-45. We have 200. ml of a buffer solution containing 0.10 M CH 3 COOH and 0.10 M NaCH 3 COO. If we add 10.00 ml of 0.20 M NaOH to this solution, what will the resulting ph be? K a (CH 3 COOH) = 1.8 x 10-5 (a) 4.83 (b) 4.66 (c) 8.44 (d) 6.43

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 6 18-46. We have 300. ml of a buffer solution containing 0.10 M CH 3 COOH and 0.40 M NaCH 3 COO. If we add 20.00 ml of 0.10 M NaOH to this solution, what will the resulting ph be? K a (CH 3 COOH) = 1.8 x 10-5 (a) 4.11 (b) 8.88 (c) 5.38 (d) 3.26 18-47. We have 100. ml of a buffer solution containing 0.25 M HF and 0.45 M NaF. If we add 5.00 ml of 0.80 M HCl to this solution, what will the resulting ph be? K a (HF) = 7.2 x 10-4 (a) 2.99 (b) 3.51 (c) 6.43 (d) 3.29 18-48. We have 550 ml of a buffer solution containing 0.50 M HNO 2 and 0.15 M NaNO 2. If we add 22.0 ml of 1.00 M HNO 3, what will the resulting ph be? K a (HNO 2 ) = 4.5 x 10-4 (a) 4.04 (b) 2.96 (c) 3.56 (d) 2.66 18-49. We add some ammonium cyanide, NH 4 CN to some water. What can be said about the ph of the resulting solution? K a (NH 4 +) = 5.6 x 10-10 ; K b (CN - ) = 2.5 x 10-5 (a) it is acidic (b) it is basic (c) it is neutral (d) nothing can be said 18-50. We add some ammonium sulfate, (NH 4 ) 2 SO 4, to some water. What can be said about the ph of the resulting solution? K a (NH 4 +) = 5.6 x 10-10 ; K b (SO 4 2-) = 8.3 x 10-13 (a) it is acidic (b) it is basic (c) it is neutral (d) nothing can be said 18-51. In order to buffer a solution at a ph of 4.57, how many grams of sodium acetate, NaCH 3 COO, should you add to 500. ml of a 0.150 M solution of acetic acid (CH 3 COOH)? (a) 8.20 g (b) 4.50 g (c) 4.11 g (d) 2.05 g 18-52. You add 25.0 ml of 0.015 M HNO 3 to 50.0 ml of 0.012 M NH 3. What is the final ph of the solution? (a) 4.97 (b) 9.03 (c) 1.82 (d) 7.00 18-53. What is the ph of the buffer solution that consists of 12.6 g of sodium acetate (NaCH 3 COO) dissolved in 150 ml of 1.8 M acetic acid (CH 3 COOH)? (a) 1.50 (b) 3.68 (c) 4.50 (d) 9.50 18-54. What is the ph of a solution created by mixing 30 ml of 0.10 M acetic acid with 15 ml of 0.150.0 M NaOH? (a) 4.74 (b) 9.25 (c) 7.00 (d) 2.87

Chapter 18: Acid-Base Reactions (Rev. April 2001) Page 7 18-55. What is the concentration of each of the species listed below when you have reached the equivalence point in a titration of 35.00 ml of 0.015 M HCl with 0.012 M NH 3? What is the ph of the final solution? [H 3 O + ] [NH 3 ] [NH 4 +] ph (a) 6.67 x 10-6 6.67 x 10-6 1.93 x 10-3 5.18 (b) 1.93 x 10-6 1.93 x 10-6 6.67 x 10-3 5.71 (c) 1.50 x 10-2 1.93 x 10-6 1.93 x 10-3 1.82 (d) 1.93 x 10-6 1.93 x 10-6 5.25 x 10-4 5.71 ANSWERS CHAPTER 18 1. c 11. d 21. b 2. c 12. c 22. a 3. a 13. a 23. a 4. b 14. b 24. c 5. a 15. d 25. d 6. c 16. c 26. c 7. b 17. a 27. a 8. a 18. b 28. b 9. d 19. a 29. d 10. b 20. d 30. c 31. d 41. b 51. c 32. b 42. d 52. b 33. b 43. a 53. c 34. d 44. b 54. a 35. a 45. a 55. b 36. c 46. c 37. b 47. d 38. d 48. d 39. a 49. b 40. c 50. a