Name ____________________________________________________ Date ______________ Class _________ Chapter 19 Study Guide: Acids, Bases & Titration – Answers 1. Differentiate between Arrhenius, Brønsted-Lowry & Lewis acids and bases. Arrhenius Brønsted-Lowry Lewis ACIDS Form hydronium ions (H3O+) in aqueous sol’n Proton (H+) donors Electron pair acceptors BASES Form hydroxide ions (OH-) in aqueous sol’n Proton (H+) acceptors Electron pair donors 2. Label the acid (A), base (B), conjugate acid (CA) and conjugate base (CB) in each of the following reactions: A B CB CA a. H2CO3 + CaCl2 CaCO3 + 2HCl A B CB CA b. 2 HCl + Ca(OH)2 CaCl2 + 2 H2O 3. Write the names or formulas for the following acids and bases: a. H2S – hydrosulfuric acid e. Nitrous acid – HNO2 b. HC2H3O2– acetic acid f. Calcium hydroxide – Ca(OH)2 c. NaOH – sodium hydroxide g. hydrochloric acid – HCl d. HNO3 – nitric acid Use the following formulas for the remaining questions: (these will not be given to you on the test!) pH + pOH = 14 Kw = [H3O+][OH-] = 1.0 10-14 + MAVA nA = MBVB nB pH = -log[H3O ] pOH = -log[OH-] 4. What is the pH of 1.34 x 10-4 M solution of hydrochloric acid? pH = -log [1.34 x 10-4M] = 3.873 5. Determine the pH and pOH of a 1.85 x 10-6 M NaOH solution. pOH = -log [1.85 x 10-6M] = 5.733 pH = 14 – 5.73 = 8.267 6. What is the [OH-] of an aqueous solution that has a pH of 5.0? pOH = 9 [OH-] = 1 x 10-9 M 7. What is the pH and the pOH of a solution with a volume of 2000. mL containing 35 grams of NaOH? Is this solution acidic or basic? 35gNaOH 1molNaOH 0.44 M NaOH 2.000L 40.00gNaOH pOH = -log[0.44M] = 0.36 pH = 14 – 0.36 = 13.64 basic 8. What is the pH of a solution that contains 0.075 grams of hydrobromic acid in 200. mL of water? 0.075gHBr 1molHBr 0.0046M HBr 0.200L 80.91gHBr pH = -log [0.0046M] = 2.34 9. What is the [H3O+] of a solution that is 1.0 x 10-3 M NaOH? What is the pH? [H3O+] = 1.0 x 10-11 M pH = 11 10. What volume of 1.75 M HNO3 is needed to neutralize 30.0 mL of 1.50 M LiOH? M1 = 1.75 M M2 = 1.5 M V1 = ? V2 = 30.0 mL n1 = 1 n2 = 1 M 2V2 n2 V1 25.7mL HNO3 M1n1 11. 95.0 mL of 0.15 M HCl are titrated with 65.0 mL of Ca(OH)2. What is the molarity of Ca(OH)2? M1 = 0.15 M HCl M2 = ? V1 = 95.0 mL V2 = 65.0 mL n1 = 1 n2 = 2 M1V1n1 M2 0.11M Ca(OH)2 V2 n2 12. What volume of 0.075 M H3PO4 is required to neutralize 45.0 mL of 0.015 M Ba(OH)2? M1 = 0.075 M M2 = 0.015 M V1 = ? V2 = 45.0 mL n1 = 3 n2 = 2 M 2V2 n2 V1 6.0mL H3 PO4 Each blank can be completed with a term, short M1n1 phrase, or a number. 19.1 Acid-Base Theories 13. three 14. Arrhenius 15. hydroxide ions 16. proton (H+) 17. acceptor 18. electron pair 19. donor 20. monoprotic 21. diprotic 22. conjugate acid-base pair 23. amphoteric Compounds can be classified as acid or bases according to __13__ different theories. An _14__ acid yields hydrogen ions in aqueous solution. An Arrhenius base yields __15_ in aqueous solution. A Brønsted-Lowry acid is a __16__ donor. A Brønsted-Lowry base is a proton __17__. In the Lewis theory, an acid is an __18__ acceptor. A Lewis base is an electron-pair __19__. An acid with one ionizable hydrogen atom is called a __20__ acid, while an acid with two ionizable hydrogen atoms is a called a __21__ acid. A __22__ is a pair of substances related by the gain or loss of a hydrogen ion. A substance that can act as both an acid and a base is called __23__. Classify as: always true, AT; sometimes true, ST; or never true, NT. 24. NT Hydrochloric acid is a strong acid that is diprotic. 25. NT The ammonium ion, NH4+, is a Brønsted-Lowry base. 26. AT A Brønsted-Lowry base is a hydrogen-ion acceptor. 27. ST A compound can act as both an acid and a base. 28. AT PBr3 is a Lewis base. Matching 29. G monoprotic acids 30. D triprotic acids 31. A acid properties 32. H base properties 33. E conjugate base 34. I conjugate acid 35. C hydronium ion (H3O+) 36. F Lewis acid 37. B Lewis base a. tastes sour and will change the color of an acidbase indicator b. an electron-pair donor c. a water molecule that gains a hydrogen ion d. acids that contain 3 ionizable hydrogens e. particle that remained when an acid has donated a hydrogen ion f. an electron-pair acceptor g. acids that contain one ionizable hydrogen h. tastes bitter and feels slippery i. particle formed when a base gains a hydrogen ion 38. Identify the Lewis acid and Lewis base in the following reaction. Explain. Lewis base: e- pair donor Lewis acid: e- pair acceptor 19.2 Hydrogen Ions and Acidity 39. ionize 40. 1 x 10-7M 41. 0-14 42. hydrogen ion 43. acidic 44. basic 45. neutral 46. 7 47. ion-product 48. hydrogen 49. hydroxide Each blank can be completed with a term, short phrase, or a number. Water molecules can __39__ to form hydrogen ions (H+) and hydroxide ions (OH-). The concentrations of these ions in pure water at 25oC are both equal to __40__ M. The pH scale, which has a range from ___41_, is used to denote the __42__ concentration of a solution. On this scale, 0 is strongly __43__, 14 is strongly __44__, and 7 is __45__. Pure water at 25oC has a pH of __46__. The __47__ constant for water has a value of 1.0 x 10-14. Thus, the product of the concentrations of __48__ ions and __49__ ions in aqueous solution will always equal 1.0 x 10-14. Classify as: always true, AT; sometimes true, ST; or never true, NT. 50. AT In an acidic solution, [H+] is greater than [OH-]. 51. ST pH indicators can give accurate pH readings for solutions. 52. AT If the [H+] in a solution increases, the [OH-] must decrease. 53. NT The [OH-] is less than 10-7 M in a basic solution. 54. NT The definition of pH is the negative logarithm of the hydroxide-ion concentration. Matching 55. C alkaline solutions a. Aqueous solution in which [H+] and [OH-]are equal b. Product of hydrogen ion and hydroxide ion 56. F pH concentrations for water 57. E self-ionization c. Base solutions d. Solution in which [H+] is less than [OH-] 58. A neutral solution 59. B ion product constant for water (Kw) e. Reaction in which two water molecules produce ions 60. G acidic solution f. The negative logarithm of the hydrogen-ion concentration 61. D basic solution g. Solution in which [H+] is greater than [OH-] 62. Calculate the hydroxide-ion concentration, [OH-], for an aqueous solution in which [H+] is 1 x 10-10 M. Is this solution acidic, basic, or neutral? [OH-] = 1 x 10-4 M basic 63. Determine the hydrogen-ion concentrations for aqueous solutions that have the following pH values. a. 3 1 x 10-3 M b. 6 1 x 10-6 M c. 10 1 x 10-10 M 19.3 Strengths of Acids and Bases Classify as: always true, AT; sometimes true, ST; or never true, NT. 64. ST Acids are completely dissociated in aqueous solution. 65. NT Diprotic acids lose both hydrogens at the same time. 66. AT Acid dissociation constants for weak acids can be calculated from experimental data. 67. ST Bases react with water to form hydroxide ions. a. Ratio of the concentration of the dissociated (or ionized) form of an acid to the concentration of the undissociated acid 69. E weak acids b. Bases that dissociate completely into metal ions and 70. A acid dissociation constant (Ka) hydroxide ions in solution c. Acids that ionize completely in aqueous solution 71. B strong bases d. Bases that do not dissociate completely in aqueous 72. D weak bases solution 73. F base dissociation constant (Kb) e. Acids that are only partially ionized in aqueous solution f. Ratio of the concentration of conjugate acid times 19.4 Neutralization Reactions concentration of conjugate base Matching 68. C strong acids 74. acid 75. hydroxide 76. water 77. neutralization 78. titration 79. equivalence 80. end point Each blank can be completed with a term, short phrase, or a number. In the reaction of a(n) __74__ with a base, hydrogen ions and __75__ ions react to produce ___76_. This reaction, called ___77_, is usually carried out by __78__. The _79__ in a titration is the point at which the acid has been neutralized. At the __80__ point of a titration, the number of equivalents of acid equals the number of equivalents of base. Classify as: always true, AT; sometimes true, ST; or never true, NT. 81. AT A solution of known concentration is called a standard (or stock) solution. 82. AT The endpoint of a titration of a strong base with a strong acid occurs when [H+] = [OH-]. 83. ST The point of neutralization is the end point of a titration. 84. NT The reaction of an acid and a base produces only water. Matching 85. C titration 86. E neutralization reactions 87. A equivalence point 88. B standard solution 89. D end point a. When the number of moles of hydrogen ions equals the number of moles of hydroxide ions b. A solution of known concentration c. A process for determining the concentration of a solution by adding a known amount of standard solution d. Point of neutralization e. Reactions between acids and bases to produce a salt and water 90. Complete and balance the equations for the following acid-base reactions. a. H3PO4 + Al(OH)3 3 H2O + AlPO4 b. 2 HI + Ca(OH)2 2 H2O + CaI2 19.5 Salts in Solution 91. salt 92. acidic 93. basic 94. neutral 95. hydrolyze or react with 96. strong 97. weak 98. buffer 99. capacity Matching Each blank can be completed with a term, short phrase, or a number. A __91__ forms when an acid is neutralized by a base. Salts can be neutral, __92__, or ___93_ in solutions. Salts of strong acid-strong base reaction produce ___94_ solutions with water. Salts formed from the neutralization of weak acids or weak bases __95__ water. They produce solutions that are acidic or basic. For example, the pH of a solution at the equivalence point is greater than 7 for a _96__ base-__97__ acid titration. Solutions that resist changes in pH are called __98__ solutions. The buffer __99__ is the amount of acid or base that can be added to a buffer without changing the pH greatly. f. The cations or anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water g. The amount of acid or base that can be added to a buffer solution before a significant change in pH can occur h. The salt produced by the titration of ammonia with hydrochloric acid i. A solution in which the pH remains relatively constant when small amounts of acid or base are added 100. F salt hydrolysis 101. I buffer 102. G buffer capacity 103. H NH4Cl 104. Predict whether an aqueous solution of each salt will be acidic, basic, or neutral. a. NH4Cl acidic b. Na2CO3 basic c. NH4NO3 acidic 19.1 Acid-Base Theories 105. Identify the hydrogen ion donor(s) and the hydrogen ion acceptor(s) for ionization of H2SO4 in water. Label the conjugate acid-base pairs. A B CB CA H2SO4+ H2O HSO4 + H3O+ 106. Identify all of the ions that may be formed when H3PO4 ionizes in water. H+, H2PO4-, HPO42-, PO43- 107. Classify the following acids as monoprotic, diprotic, or triprotic. a. HCOOH – monoprotic b. HBr – monoprotic c. H2SO3 – diprotic d. H3ClO4 – triprotic 108. What would you expect to happen when lithium metal is added to water? Show the chemical reaction. Li + H2O LiOH + H2 109. In the following chemical reaction, identify the Lewis acid and base. BF3 + F- BF4- 19.2 Hydrogen Ions and Acidity 110. A solution has a hydrogen ion concentration of 1 x 10-6M. What is its pH? pH = 6 111. What is the pH of a solution if the [H+] = 7.2 x 10-9M? pH = 8.14 112. What is the pOH of a solution if the [OH-] = 3.5 x 10-2M? pOH = 1.46 113. What is the pOH of a solution that has a pH of 3.4? pOH = 10.6 114. Classify each solution as acidic, basic, or neutral. a. [H+] = 2.5 x 10-9M basic d. [H+] = 1 x 10-7M neutral b. pOH = 12.0 acidic e. pH = 0.8 acidic c. [OH-] = 9.8 x 10-11M acidic 115. Calculate the pH of each solution and classify each as acidic, basic or neutral. a. [H+] = 1 x 10-5M 5, acidic c. [OH-] = 2.2 x 10-7M b. [H+] = 4.4 x 10-11M 10.85, basic d. pOH = 1.4 7.34, basic 12.6, basic 116. Why is there a minus sign in the definition of pH? 117. A solution has a pOH of 12.4. What is the pH of the solution? pH = 1.6 118. What is the pH of a solution with [OH-] = 1 x 10-3M? pH = 11 119. What is the pH of a 25.0 L solution containing 0.450 grams of HCl, 1.70 grams of H2SO4, and 2.50 grams of HNO3? 0.450 g HCl x 1 mol HCl/36.46 g HCl = 0.01234 mol H+ 1.70 g H2SO4 x 1 mol H2SO4/98.08 g H2SO4 = 0.01733 mol H2SO4 x 2 = 0.03467 mol H+ 2.50 g HNO3 x 1 mol HNO3/63.02 g HNO3 = 0.03967 mol H+ mol H+ = 0.01234 mol H+ + 0.01733 mol H+ = 0.03967 mol H+/25.0 L = 0.00347 M H+ pH = -log(0.00347) = 2.460 = pH 120. What is pH and pOH of a solution that was made by adding 250. mL of water to 450. mL of 2.75 x 10-3 M HCl? M1 = 2.75 x 10-3 M HCl M2 = ? V1 = 450. mL V2 = 450. mL + 250. mL = 700. mL M 1V1 M2 1.77 10 3 M HCl V2 pH = -log[H3O+] = =log(1.77 x 10-3) = 2.753 pH = 2.753 pOH = 11.247 19.3 Strengths of Acids and Bases 121. Rank 1M of these compounds in order of increasing hydrogen ion concentration: weak acid, strong acid, strong base, weak base. Strong base, weak base, weak acid, strong acid 122. Match each solution with its correct description. a. dilute, weak acid (4) (1) 18M H2SO4 (aq) b. dilute, strong base (2) (2) 0.5M NaOH (aq) c. concentrated, strong acid (1) (3) 15M NH3 (aq) d. dilute, strong acid (5) (4) 0.1M HC2H3O2(aq) e. concentrated, weak base (3) (5) 0.1M HCl (aq) 123. A 0.10M solution of formic acid has an equilibrium [H+] = 6.3 x 10-5M. What is the pH of this solution? pH = -log[H3O+] = -log(6.3 x 10-5) = 4.20 124. A 0.10M solution of hydrocyanic acid, HCN, has an equilibrium hydrogen ion concentration of 6.3 x 10-6M. What is the pH of this solution? pH = -log[H3O+] = -log(6.3 x 10-6) = 5.20 19.4 Neutralization Reactions 125. What is the molarity of a sodium hydroxide solution if 38 mL of the solution is titrated to the end point with 14 mL of 0.70M sulfuric acid? Acid – H2SO4 Base – NaOH M1 = 0.70 M M2 = ? MVn M 2 1 1 1 0.52 M NaOH V1 = 14 mL V2 = 38 mL V2 n2 n1 = 2 n2 = 1 126. If 24.6 mL of a Ca(OH)2 solution are needed to neutralize 14.2 mL of a 0.0140M HC2H3O2, what is the concentration of the calcium hydroxide solution? Acid – HC2H3O2 Base – Ca(OH)2 M1 = 0.0140 M M2 = ? M 1V1n1 M 4.04 10 3 M Ca(OH ) 2 2 V1 = 14.2 mL V2 = 24.6 mL V2 n2 n1 = 1 n2 = 2 127. A 12.4 mL solution of H2SO4 is completed neutralized by 19.8 mL of 0.0100M Ca(OH)2. What is the concentration of the H2SO4 solution? Acid – H2SO4 Base – Ca(OH)2 M1 = ? M2 = 0.0100 M M Vn M 1 2 2 2 0.0160 M H 2 SO4 V1 = 12.4 mL V2 = 19.8 mL V1n1 n1 = 2 n2 = 2 128. What volume of 0.12M Ba(OH)2 is needed to neutralize 12.2 mL of 0.25M HCl? Acid – HCl Base – Ba(OH)2 M1 = 0.25 M M2 = 0.12 M MVn V1 = 12.2 mL V2 = ? V2 1 1 1 13mLBa (OH ) 2 M 2 n2 n1 = 1 n2 = 2 129. A 55.0-mg sample of Al(OH)3 is reacted with 0.200M HCl. How many milliliters of the acid are needed to neutralize the Al(OH)3? Al(OH)3 + 3HCl 3H2O + AlCl3 55.0mgAl(OH ) 3 130. 1molAl (OH ) 3 1g 3molHCl 1Lsol ' n 1000mL 10.6mLHCl 1000mg 78.01gAl (OH ) 3 1molAl (OH ) 3 0.200molHCl 1L Complete the following rules: a. strong acid + strong base neutral solution b. strong acid + weak base acidic solution c. weak acid + strong base basic solution