chapter15 (2)

Chemistry, 6e (McMurry/Fay) Chapter 15 Applications of Aqueous Equilibria 15.1 Multiple-Choice Questions 1) Which is a net ionic equation for the neutralization of a strong acid with a strong base? A) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) B) H3O+(aq) + OH-(aq) ⇌ 2 H2O(l) C) HF(aq) + NaOH(aq) ⇌ H2O(l) + NaF(aq) D) HF(aq) + OH-(aq) ⇌ H2O(l) + F-(aq) Answer: B Topic: Section 15.1 Neutralization Reactions 2) Which is a net ionic equation for the neutralization of a weak acid with a strong base? A) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) B) H3O+(aq) + OH-(aq) ⇌ 2 H2O(l) C) HF(aq) + NaOH(aq) ⇌ H2O(l) + NaF(aq) D) HF(aq) + OH-(aq) ⇌ H2O(l) + F-(aq) Answer: D Topic: Section 15.1 Neutralization Reactions 3) Which is a net ionic equation for the neutralization reaction of a strong acid with a weak base? A) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) B) H3O+(aq) + OH-(aq) ⇌ 2 H2O(l) C) HCl(aq) + NH3(aq) ⇌ NH4Cl(aq) D) H3O+(aq) + NH3(aq) ⇌ NH4+(aq) + H2O(l) Answer: D Topic: Section 15.1 Neutralization Reactions

4) Which is a net ionic equation for the neutralization reaction of a weak acid with a weak base? A) H3O+(aq) + OH-(aq) ⇌ 2 H2O(l) B) HF(aq) + NH3(aq) ⇌ NH4+(aq) + F-(aq) C) HF(aq) + OH-(aq) ⇌ H2O(l) + F-(aq) D) H3O+(aq) + NH3(aq) ⇌ NH4+(aq) + H2O(l) Answer: B Topic: Section 15.1 Neutralization Reactions

1 Copyright © 2012 Pearson Education, Inc.

5) What is the equation relating the equilibrium constant Kn for the neutralization of a weak acid with a weak base to the Ka of the acid, the Kb of the base and Kw? A) Kn = KaKbKw K K B) Kn = a b Kw K K C) Kn = a w Kb K K D) Kn = b w Ka Answer: B Topic: Section 15.1 Neutralization Reactions 6) What is the approximate value of the equilibrium constant, Kn, for the neutralization of acetic acid with sodium hydroxide, shown in the equation below? The Ka for acetic acid is 1.8 × 10–5. CH3CO2H(aq) + NaOH(aq) ⇌ H2O(l) + NaCH3CO2(aq)

A) 1.8 × 10-19 B) 5.6 × 10-10 C) 1.8 × 10-8 D) 1.8 × 109 Answer: D Topic: Section 15.1 Neutralization Reactions 7) What is the approximate value of the equilibrium constant, Kn, for the neutralization of pyridine with hydrochloric acid, shown in the equation below? The Kb for pyridine is 1.8 × 10–9. HCl(aq) + C5H5N(aq) ⇌ C5H5NHCl(aq)

A) 5.6 × 10-10 B) 5.6 × 10-6 C) 1.8 × 105 D) 5.6 × 108 Answer: C Topic: Section 15.1 Neutralization Reactions 8) What is the approximate value of the equilibrium constant, Kn, for the neutralization of nitrous acid with ammonia, shown in the equation below? The Ka for HNO2 is 4.5 × 10–4 and the Kb for NH3 is 1.8 × 10–5.

HNO2(aq) + NH3(aq) ⇌ NH4NO2(aq)

A) 8.1 × 105 B) 1.8 × 109 C) 4.5 × 1010 D) 8.1 × 1019 Answer: A Topic: Section 15.1 Neutralization Reactions 2 Copyright © 2012 Pearson Education, Inc.

9) What is the approximate value of the equilibrium constant, Kn, for the neutralization of hydrochloric acid with sodium hydroxide, shown in the equation below? HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) A) 1.0 × 102 B) 1.0 × 107 C) 1.0 × 1014 D) 1.0 × 1028 Answer: C Topic: Section 15.1 Neutralization Reactions 10) The neutralization constant Kn for the neutralization of acetylsalicylic acid (C9H8O4) and codeine (C18H21NO3) is 4.8 × 104. The acid dissociation constant Ka for acetylsalicylic acid is 3.0 × 10-4. What is the base dissociation constant Kb for codeine? A) 4.8 × 10-24 B) 6.3 × 10-23 C) 1.6 × 10-6 D) 1.4 × 1015 Answer: C Topic: Section 15.1 Neutralization Reactions 11) The neutralization constant Kn for the neutralization of phenobarbital (C12H12N2O3) and morphine (C17H19NO3) is 2.9. The acid dissociation constant Ka for phenobarbital is 3.9 × 10-8. What is the base dissociation constant Kb for morphine? A) 1.3 × 10-22 B) 6.3 × 10-23 C) 7.4 × 10-7 D) 1.1 × 107 Answer: C Topic: Section 15.1 Neutralization Reactions 12) Which of these neutralization reactions has a pH = 7 when equal molar amounts of acid and base are mixed? A) CH3CO2H(aq) + NaOH(aq) ⇌ H2O(l) + NaCH3CO2(aq) B) HCl(aq) + C5H5N(aq) ⇌ C5H5NHCl(aq) C) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) D) HNO2(aq) + NH3(aq) ⇌ NH4NO2(aq) Answer: C Topic: Section 15.1 Neutralization Reactions

3 Copyright © 2012 Pearson Education, Inc.

13) Which of these neutralization reactions has a pH < 7 when equal molar amounts of acid and base are mixed? A) CH3CO2H(aq) + NaOH(aq) ⇌ H2O(l) + NaCH3CO2(aq) B) HCl(aq) + C5H5N(aq) ⇌ C5H5NHCl(aq) C) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) D) H2SO4(aq) + 2 KOH(aq) ⇌2 H2O(l) + K2SO4(aq) Answer: B Topic: Section 15.1 Neutralization Reactions 14) Which of these neutralization reactions has a pH > 7 when equal moles of acid and base are mixed? A) CH3CO2H(aq) + NaOH(aq) ⇌ H2O(l) + NaCH3CO2(aq) B) HCl(aq) + C5H5N(aq) ⇌ C5H5NHCl(aq) C) HCl(aq) + NaOH(aq) ⇌ H2O(l) + NaCl(aq) D) H2SO4(aq) + 2 KOH(aq) ⇌2 H2O(l) + K2SO4(aq) Answer: A Topic: Section 15.1 Neutralization Reactions 15) What is the common ion in a solution prepared by mixing 0.10 M NaCH3CO2 with 0.10 M CH3CO2H? A) H3O+ B) Na+ C) CH3CO2D) OHAnswer: C Topic: Section 15.2 The Common-Ion Effect 16) When 50 mL of 0.10 M NH4Cl is added to 50 mL of 0.10 M NH3, relative to the pH of the 0.10 M NH3 solution the pH of the resulting solution will A) become 7. B) decrease. C) increase. D) remain the same. Answer: B Topic: Section 15.2 The Common-Ion Effect 17) When 50 mL of 0.10 M NaF is added to 50 mL of 0.10 M HF, relative to the pH of the 0.10 M HF solution the pH of the resulting solution will A) become 7. B) decrease. C) increase. D) remain the same. Answer: C Topic: Section 15.2 The Common-Ion Effect

4 Copyright © 2012 Pearson Education, Inc.

18) What is the hydronium ion concentration in a solution prepared by mixing 50.00 mL of 0.10 M HCN with 50.00 mL of NaCN? Assume that the volumes of the solutions are additive and that Ka = 4.9 × 10-10 for HCN. A) 2.4 × 10-10 M B) 4.9 × 10-10 M C) 9.8 × 10-10 M D) 7.0 × 10-6 M Answer: C Topic: Section 15.2 The Common-Ion Effect 19) What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M CH3CO2H with 25.00 mL of 0.050 M CH3CO2Na? Assume that the volume of the solutions are additive and that Ka = 1.8 × 10-5 for CH3CO2H. A) 2.87 B) 4.44 C) 4.74 D) 5.05 Answer: B Topic: Section 15.2 The Common-Ion Effect 20) What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M NH3 with 25.00 mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb = 1.8 × 10-5 for NH3. A) 8.95 B) 9.26 C) 9.56 D) 11.13 Answer: C Topic: Section 15.2 The Common-Ion Effect 21) What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M methylamine, CH3NH2, with 25.00 mL of 0.10 M methylammonium chloride, CH3NH3Cl? Assume that the volume of the solutions are additive and that Kb = 3.70 × 10-4 for methylamine. A) 10.27 B) 10.57 C) 10.87 D) 11.78 Answer: B Topic: Section 15.2 The Common-Ion Effect

5 Copyright © 2012 Pearson Education, Inc.

22) When equal molar amounts of the following sets of compounds are mixed in water, which will not form a buffer solution? A) NaH2PO4 with Na2HPO4 B) NH3 with NH4Cl C) CH3CO2H with NaCH3CO2 D) HNO3 with NaNO3 Answer: D Topic: Section 15.3 Buffer Solutions 23) Which of the following combinations of chemicals could be used to make a buffer solution? A) HCl/NaOH B) HCl/NH3 C) HCl/H3PO4 D) NaOH/NH3 Answer: B Topic: Section 15.3 Buffer Solutions 24) Which statement about buffers is true? A) Buffers have a pH = 7. B) Buffers consist of a strong acid and its conjugate base. C) A buffer does not change pH on addition of a strong acid or strong base. D) Buffers resist change in pH upon addition of small amounts of strong acid or strong base. Answer: D Topic: Section 15.3 Buffer Solutions 25) What is the pH of a buffered system made by dissolving 17.42 g of KH2PO4 and 20.41 g of K2HPO4 in water to give a volume of 200.0 mL? The Ka2 for dihydrogen phosphate is 6.2 × 10-8 and the equilibrium reaction of interest is H2PO4-(aq) + H2O(l) ⇌ H3O+(aq) + HPO4-(aq). A) 7.03 B) 7.17 C) 7.38 D) 7.58 Answer: B Topic: Section 15.3 Buffer Solutions 26) What is the pH of a buffer system made by dissolving 10.70 grams of NH4Cl and 20.00 mL of 12.0 M NH3 in enough water to make 1.000 L of solution? Kb = 1.8 × 10-5 for NH3. A) 9.18 B) 9.26 C) 9.34 D) 11.03 Answer: C Topic: Section 15.3 Buffer Solutions

6 Copyright © 2012 Pearson Education, Inc.

27) TRIS {(HOCH2)3CNH2} is one of the most common buffers used in biochemistry. A solution is prepared by adding enough TRIS and 12 M HCl(aq) to give 1.00 L of solution with [TRIS] = 0.30 M and [TRISH+] = 0.60 M. What is the pH of this buffered system if the pKb is 5.92? A) 5.92 B) 6.22 C) 7.78 D) 8.08 Answer: C Topic: Section 15.3 Buffer Solutions 28) A buffer solution is prepared by dissolving 0.200 mol of NaH2PO4 and 0.100 mol of NaOH in enough water to make 1.00 L of solution. What is the pH of the H2PO4-/HPO42- buffer if the Ka2 = 6.2 × 10-8? A) 6.91 B) 7.21 C) 7.51 D) 7.71 Answer: B Topic: Section 15.3 Buffer Solutions 29) What is the pH of 1 L of 0.30 M TRIS, 0.60 M TRISH+ buffer to which one has added 5.0 mL of 12 M HCl? The Kb for the TRIS/TRISH+ is 1.2 × 10-6. A) 5.92 B) 6.36 C) 7.36 D) 7.64 Answer: D Topic: Section 15.3 Buffer Solutions 30) A buffer solution is prepared by dissolving 27.22 g of KH2PO4 and 3.37 g of KOH in enough water to make 0.100 L of solution. What is the pH of the H2PO4-/HPO42- buffer if the Ka2 = 6.2 × 10-8? A) 6.84 B) 7.00 C) 7.21 D) 7.84 Answer: A Topic: Section 15.3 Buffer Solutions 31) What is the [CH3CO2-]/[CH3CO2H] ratio necessary to make a buffer solution with a pH of 4.44? Ka = 1.8 × 10-5 for CH3CO2H. A) 0.50:1 B) 0.94:1 C) 1.1:1 D) 2.0:1 Answer: A Topic: Section 15.3 Buffer Solutions 7 Copyright © 2012 Pearson Education, Inc.

32) What is the pH of a buffer solution made by mixing 50.0 mL of 0.100 M potassium hydrogen phthalate with 13.6 mL of 0.100 M NaOH and diluting the mixture to 100.0 mL with water? The Ka2 for hydrogen phthalate is 3.1 × 10-6. A) 3.25 B) 5.08 C) 5.51 D) 5.94 Answer: B Topic: Section 15.3 Buffer Solutions 33) What volume of 0.100 M NaOH is needed to make 100.0 mL of a buffer solution with a pH of 6.00 if one starts with 50.0 mL of 0.100 M potassium hydrogen phthalate? The Ka2 for potassium hydrogen phthalate is 3.1 × 10-6. A) 22.4 mL B) 27.6 mL C) 30.2 mL D) 37.8 mL Answer: D Topic: Section 15.3 Buffer Solutions 34) What is the magnitude of the change in pH when 0.005 moles of HCl is added to 0.100 L of a buffer solution that is 0.100 M in CH3CO2H and 0.100 M NaCH3CO2? The Ka for acetic acid is1.8 × 10-5. A) 0.00 B) 0.20 C) 0.47 D) 1.30 Answer: C Topic: Section 15.3 Buffer Solutions 35) What is the resulting pH when 0.005 moles of KOH is added to 0.100 L of a buffer solution that is 0.100 M in H2PO4- and 0.100 M HPO42- and the Ka2 = 6.2 × 10-8? A) 5.21 B) 5.61 C) 6.73 D) 7.69 Answer: D Topic: Section 15.3 Buffer Solutions 36) What is the Henderson-Hasselbalch equation for the acidic buffer HA/A-? A) pH = -log[H3O+] B) pH = 14 - pOH C) pH = pKa + log{[A-]/[HA]} D) pH = pKa - log{[A-]/[HA]} Answer: C Topic: Section 15.4 The Henderson-Hasselbalch Equation 8 Copyright © 2012 Pearson Education, Inc.

37) What is not a correct expression for the weak acid HA? A) Ka = [H3O+][A-]/[HA] B) pKa = pH - log{[A-]/[HA]} C) pKa = logKa D) pKa = 14 - pKb Answer: C Topic: Section 15.4 The Henderson-Hasselbalch Equation 38) Which is the best acid to use in the preparation of a buffer with pH = 3.3? A) HOI (Ka = 2.0 × 10–11) B) HNO2 (Ka = 4.5 × 10–4) C) HNO3 D) HIO3 ((Ka = 1.7 × 10–1) Answer: B Topic: Section 15.4 The Henderson-Hasselbalch Equation 39) Which is the best acid to use in the preparation of a buffer with pH = 9.3? A) CH3NH2 (Kb = 3.7 × 10–4) B) NH3 (Kb = 1.8 × 10–5) C) NH2OH (Kb = 9.1 × 10–9) D) C6H5NH2 (Kb = 4.3 × 10–10) Answer: B Topic: Section 15.4 The Henderson-Hasselbalch Equation 40) What is the percent dissociation of glycine if the solution has a pH = 8.60 and a pKa = 9.60? A) 50% B) 9% C) 5% D) 1% Answer: B Topic: Section 15.4 The Henderson-Hasselbalch Equation 41) What is the percent dissociation of acetic acid if the solution has a pH = 4.74 and a pKa = 4.74? A) 100% B) 50% C) 10% D) 1% Answer: B Topic: Section 15.4 The Henderson-Hasselbalch Equation

9 Copyright © 2012 Pearson Education, Inc.

42) What is the percent dissociation of ascorbic acid if the solution has a pH = 5.50 and a pKa = 4.10? A) 96% B) 10% C) 5% D) 1% Answer: A Topic: Section 15.4 The Henderson-Hasselbalch Equation 43) At what pH is the amino acid glycine with a Ka of 2.51 × 10-10 sixty-six (66%) percent dissociated? A) 9.60 B) 9.89 C) 10.10 D) 10.60 Answer: B Topic: Section 15.4 The Henderson-Hasselbalch Equation 44) What volume of 5.00 × 10–3 M HNO3 is needed to titrate 100.00 mL of 5.00 × 10–3 M Ca(OH)2 to the equivalence point? A) 12.5 mL B) 50.0 mL C) 100. mL D) 200. mL Answer: D Topic: Section 15.6 Strong Acid - Strong Base Titrations 45) What is the pH of a solution made by mixing 30.00 mL of 0.10 M HCl with 40.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. A) 0.85 B) 1.85 C) 12.15 D) 13.15 Answer: C Topic: Section 15.6 Strong Acid - Strong Base Titrations 46) Which of the following titrations result in a basic solution at the equivalence point? A) HI titrated with NaCH3CO2 B) HOCl titrated with NaOH C) HBr titrated with KOH D) Pb(NO3)2 titrated with NaI Answer: B Topic: Section 15.7 Weak Acid – Strong Base Titrations

10 Copyright © 2012 Pearson Education, Inc.

47) What is the pH at the equivalence point of a weak acid-strong base titration? A) pH < 7 B) pH = 7 C) pH > 7 D) pH = 14.00 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 48) What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid requires 29.80 mL of 0.0567 M NaOH? Ka = 1.8 × 10-4 for formic acid. A) 2.46 B) 5.88 C) 8.12 D) 11.54 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 49) What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous hydrofluoric acid requires 30.00 mL of 0.400 M NaOH? Ka = 6.76 × 10-4 for HF. A) 1.74 B) 5.75 C) 8.25 D) 12.26 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 50) The equivalence point pH of the titration of four weak acids is given. Which is the strongest acid? A) 7.24 B) 7.86 C) 8.12 D) 8.43 Answer: A Topic: Section 15.7 Weak Acid – Strong Base Titrations 51) Formic acid (HCO2H, Ka = 1.8 × 10-4) is the principal component in the venom of stinging ants. What is the molarity of a formic acid solution if 25.00 mL of the formic acid solution requires 29.80 mL of 0.0567 M NaOH to reach the equivalence point? A) 0.0134 M B) 0.0476 M C) 0.0567 M D) 0.0676 M Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations

11 Copyright © 2012 Pearson Education, Inc.

52) What is the pH of the resulting solution if 30.00 mL of 0.10 M acetic acid is added to 10.00 mL of 0.10 M NaOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10-5 for CH3CO2H. A) 9.56 B) 8.95 C) 5.05 D) 4.44 Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations 53) What is the pH of a solution made by mixing 30.00 mL of 0.10 M acetic acid with 30.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10-5 for CH3CO2H. A) 5.28 B) 7.00 C) 8.72 D) 10.02 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 54) What is the pH of a solution made by mixing 30.00 mL of 0.10 M acetic acid with 40.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10-5 for CH3CO2H. A) 8.26 B) 9.26 C) 11.13 D) 12.15 Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations 55) Which of the following titrations result in an acidic solution at the equivalence point? A) CH3COOH titrated with NaOH B) KF titrated with KOH C) HCl titrated with NaOH D) C5H5N titrated with HCl Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 56) Sodium hypochlorite, NaOCl, is the active ingredient in household bleach. What is the concentration of hypochlorite ion if 20.00 mL of bleach requires 28.30 mL of 0.500 M HCl to reach the equivalence point? A) 0.208 M B) 0.353 M C) 0.708 M D) 1.21 M Answer: C Topic: Section 15.8 Weak Base – Strong Acid Titrations

12 Copyright © 2012 Pearson Education, Inc.

57) What is the pH at the equivalence point of a weak base-strong acid titration if 20.00 mL of NaOCl requires 28.30 mL of 0.50 M HCl? Ka = 3.0 × 10-8 for HOCl. A) 0.30 B) 3.18 C) 3.76 D) 4.03 Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 58) The equivalence point pH of the titration of four weak bases is given. Which is the strongest base? A) 4.21 B) 5.67 C) 6.33 D) 7.58 Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 59) What is the pH of the resulting solution if 25 mL of 0.432 M methylamine, CH3NH2, is added to 15 mL of 0.234 M HCl? Assume that the volumes of the solutions are additive. Ka = 2.70 × 10-11 for CH3NH3+. A) 3.11 B) 3.74 C) 10.26 D) 10.89 Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 60) Sulfurous acid, H2SO3 has acid dissociation constants Ka1 = 1.5 × 10–2 and Ka2 = 6.3 × 10–8. What is the pH after 10.00 mL of 0.1000 M NaOH is added to 10.00 mL of 0.1000 M H2SO3? A) 1.82 B) 3.60 C) 4.25 D) 7.20 Answer: C Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations 61) Oxalic acid, H2C2O4 has acid dissociation constants Ka1 = 5.9 × 10–2 and Ka2 = 6.4 × 10–5. What is the pH after 20.00 mL of 0.0500 M NaOH is added to 5.00 mL of 0.2000 M H2C2O4? A) 1.23 B) 2.10 C) 2.80 D) 4.19 Answer: C Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations

13 Copyright © 2012 Pearson Education, Inc.

62) The dissociation equilibrium constants for the protonated form of alanine (a diprotic amino acid, H2X+) are Ka1 = 4.6 × 10-3 and Ka2 = 2.0 × 10-10. What is the pH of 50.00 mL of a 0.0500 M solution of alanine after 25.00 mL of 0.100 M NaOH has been added? A) 2.34 B) 4.85 C) 5.59 D) 6.72 Answer: C Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations 63) The dissociation equilibrium constants for the protonated form of alanine (a diprotic amino acid, H2X+) are Ka1 = 4.6 × 10-3 and Ka2 = 2.0 × 10-10. What is the pH of 50.00 mL of a 0.050 M solution of alanine after 37.50 mL of 0.100 M NaOH has been added? A) 4.85 B) 6.02 C) 7.39 D) 9.70 Answer: D Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations 64) The dissociation equilibrium constants for the protonated form of alanine (a diprotic amino acid H2X+) are Ka1 = 4.6 × 10-3 and Ka2 = 2.0 × 10-10. What is the pH of 50.00 mL of a 0.100 M solution of alanine after 100.00 mL of 0.100 M NaOH has been added? A) 9.70 B) 10.69 C) 11.11 D) 12.70 Answer: C Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations 65) The balanced equation for the solubility equilibrium of Fe(OH)2 is shown below. What is the equilibrium constant expression for the Ksp of Fe(OH)2? Fe(OH)2(s) ⇌ Fe2+(aq) + 2 OH-(aq) A) Ksp = {[Fe2+][OH-]2}/{[Fe(OH)2][H2O]} B) Ksp = {[Fe2+][OH-]2}/[Fe(OH)2] C) Ksp = [Fe2+][OH-]2 D) Ksp = 1/{[Fe2+][OH-]2} Answer: C Topic: Section 15.10 Solubility Equilibria

14 Copyright © 2012 Pearson Education, Inc.

66) What is the equilibrium constant expression for the Ksp of Ca3(PO4)2? A) Ksp = [Ca2+]3[PO43-]2 B) Ksp = {[Ca2+]3[PO43-]2}/[Ca3PO4] C) Ksp = {[Ca2+]3[PO43-]2}/{[Ca3PO4][H2O]} D) Ksp = 1/{[Ca2+]3[PO43-]2} Answer: A Topic: Section 15.10 Solubility Equilibria 67) What is the silver ion concentration for a saturated solution of Ag2CO3 if the Ksp for Ag2CO3 is 8.4 × 10-12? A) 2.90 × 10-6 M B) 2.03 × 10-4 M C) 2.56 × 10-4 M D) 4.06 × 10-4 M Answer: C Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 68) What is the chromium ion concentration for a saturated solution of Cr(OH)3 if the Ksp for Cr(OH)3 is 6.7 × 10-31? A) 8.19 × 10-16 M B) 1.26 × 10-8 M C) 2.17 × 10-8 M D) 3.76 × 10-8 M Answer: B Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 69) What is the most soluble salt of the following set? A) Ba(OH)2 with Ksp = 5.0 × 10-3 B) Ca(OH)2 with Ksp = 4.7 × 10-6 C) Cd(OH)2 with Ksp = 5.3 × 10-15 D) Fe(OH)2 with Ksp = 2.5 × 10-37 Answer: A Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 70) What is the most soluble salt of the following set? A) AgCN with Ksp = 6.0 × 10-17 B) Al(OH)3 with Ksp = 1.9 × 10-33 C) Fe(OH)3 with Ksp = 2.6 × 10-39 D) Sn(OH)2 with Ksp = 1.6 × 10-19 Answer: D Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp

15 Copyright © 2012 Pearson Education, Inc.

71) Calculate the Ksp for silver sulfate if the solubility of Ag2SO4 in pure water is 4.5 g/L. A) 3.0 × 10-6 B) 1.2 × 10-5 C) 2.1 × 10-4 D) 4.2 × 10-4 Answer: B Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 72) Calculate the solubility (in g/L) of silver carbonate in water at 25°C if the Ksp for Ag2CO3 is 8.4 × 10-12. A) 8.0 × 10-4 g/L B) 3.5 × 10-2 g/L C) 4.4 × 10-2 g/L D) 5.6 × 10-2 g/L Answer: B Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 73) What is the molar solubility of CaF2 in 0.10 M NaF solution at 25°C? The Ksp for CaF2 is A) 8.5 × 10-10 M B) 3.4 × 10-10 M C) 3.4 × 10-9 M D) 2.0 × 10-4 M Answer: C Topic: Section 15.12 Factors That Affect Solubility 74) What is the molar solubility of Mg(OH)2 in a basic solution with a pH of 12.00? Ksp for Mg(OH)2 is 5.6 × 10-12. A) 5.6 × 10-10 M B) 5.6 × 10-8 M C) 2.4 × 10-6 M D) 1.1 × 10-4 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 75) Calculate the molar solubility of thallium(I) chloride in 0.30 M NaCl at 25°C. Ksp for TlCl is 1.7 × 10-4. A) 5.1 × 10-5 M B) 5.7 × 10-4 M C) 7.1 × 10-3 M D) 1.3 × 10-2 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 16 Copyright © 2012 Pearson Education, Inc.

76) What is the molar solubility of lead(II) chromate in 0.10 M HNO3 if the Ksp for PbCrO4 is 2.8 × 10-13? and the Ka2 for H2CrO4 is 3.0 × 10-7? Note that H2CrO4 is considered to be a strong acid. A) 9.2 × 10-11 M B) 2.9 × 10-10 M C) 9.3 × 10-7 M D) 3.1 × 10-4 M Answer: D Topic: Section 15.12 Factors That Affect Solubility 77) In which of the following solutions would solid PbCl2 be expected to be the least soluble at 25°C? A) 0.1 M HCl B) 0.1 M NaCl C) 0.1 M CaCl2 D) 0.1 M KNO3 Answer: C Topic: Section 15.12 Factors That Affect Solubility 78) What is the molar solubility of AgCl in 0.10 M NH3? Ksp for AgCl is 1.8 × 10-10 and the Kf for Ag(NH3)2+ is 1.7 × 107. A) 1.3 × 10-5 M B) 5.0 × 10-3 M C) 5.5 × 10-3 M D) 5.5 × 10-2 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 79) What is the molar solubility of AgCl in 1.0 M K2S2O3 if the complex ion Ag(S2O3)23- forms? The Ksp for AgCl is 1.8 × 10-10 and the Kf for Ag(S2O3)23- is 2.9 × 1013. A) 0.50 M B) 1.0 M C) 1.5 M D) 2.0 M Answer: A Topic: Section 15.12 Factors That Affect Solubility 80) What is the molar solubility of AgCl in 0.10 M NaCN if the colorless complex ion Ag(CN)2- forms? Ksp for AgCl is 1.8 × 10-10 and Kf for Ag(CN)2- is A) 0.050 M B) 0.10 M C) 0.20 M D) 0.40 M Answer: A Topic: Section 15.12 Factors That Affect Solubility 17 Copyright © 2012 Pearson Education, Inc.

81) Which of the following metal hydroxides are amphoteric? A) Al(OH)3, Zn(OH)2, Cr(OH)3, Sn(OH)2 B) Cu(OH)2, Mn(OH)2, Fe(OH)2, Fe(OH)3 C) Be(OH)2, Ca(OH)2, Ba(OH)2, Sr(OH)3 D) LiOH, NaOH, KOH, RbOH Answer: A Topic: Section 15.12 Factors That Affect Solubility 82) Which of the following reactions are not consistent with the concept of acid base amphoterism? A) Al(OH)3(s) + OH-(aq) → Al(OH)4-(aq) B) Al(OH)3(s) + 3 H3O+(aq) → Al3+(aq) + 6 H2O(l) C) H2O(l) + H2O(l) ⇌ H3O+(aq) + OH-(aq) D) Al(OH)3(s) ⇌ Al3+(aq) + 3 OH-(aq) Answer: D Topic: Section 15.12 Factors That Affect Solubility 83) Precipitation of an ionic compound will occur upon mixing of desired reagents if the initial ion product is ________. A) greater than the Ksp B) equal to the pKsp C) equal to the Ksp D) less than the Ksp Answer: A Topic: Section 15.13 Precipitation of Ionic Compounds 84) Potassium chromate is slowly added to a solution containing 0.20 M AgNO3 and 0.20 M Ba(NO3)2. Describe what happens if the Ksp for Ag2CrO4 is 1.1 × 10-12 and the Ksp of BaCrO4 is 1.2 × 10-10. A) The BaCrO4 precipitates first out of solution. B) The Ag2CrO4 precipitates first out of solution and then BaCrO4 precipitates. C) Both BaCrO4 and Ag2CrO4 precipitate simultaneously out of solution. D) Neither BaCrO4 nor Ag2CrO4 precipitates out of solution. Answer: B Topic: Section 15.13 Precipitation of Ionic Compounds 85) 0.10 M potassium chromate is slowly added to a solution containing 0.20 M AgNO3 and 0.20 M Ba(NO3)2. What is the Ag+ concentration when BaCrO4 just starts to precipitate? Ksp for Ag2CrO4 and BaCrO4 are 1.1 × 10-12 and 1.2 × 10-10, respectively. A) 6.5 × 10-5 M B) 1.3 × 10-4 M C) 3.2 × 10-4 M D) 4.3 × 10-2 M Answer: D Topic: Section 15.13 Precipitation of Ionic Compounds 18 Copyright © 2012 Pearson Education, Inc.

86) Which metal sulfides can be precipitated from a solution that is 0.01 M in Mn2+, Zn2+, Pb2+ and Cu2+ and 0.10 M in H2S at a pH of 1.0?

A) MnS B) CuS C) PbS, CuS D) ZnS, PbS, CuS Answer: D Topic: Section 15.13 Precipitation of Ionic Compounds 87) Which metal sulfides can be precipitated from a solution that is 0.01 M in Mn2+, Zn2+, Pb2+ and Cu2+ and 0.10 M in H2S at a pH of 0.50?

A) MnS B) CuS C) PbS, CuS D) ZnS, PbS, CuS Answer: C Topic: Section 15.13 Precipitation of Ionic Compounds 88) Which metal ions can be precipitated out of solution as chlorides? A) Ag+, Hg2+, Co2+ B) Cu2+, Cd2+, Bi3+ C) Ag+, Hg22+, Pb2+ D) Na+, K+, Mg2+ Answer: C Topic: Section 15.13 Precipitation of Ionic Compounds

19 Copyright © 2012 Pearson Education, Inc.

89) A solution may contain the following ions Ag+, Cu2+, Cd2+, Mn2+, Ni2+ and Na+. A white precipitate formed when 0.10 M NaCl was added and after this was removed the solution was treated with H2S gas under acidic conditions and no precipitate formed. When the solution was made basic and again treated with H2S gas a dark colored precipitate formed. If no further tests were made then what conclusions can you draw? A) possible ions present Ag+, Mn2+, Ni2+ B) possible ions present Ag+, Mn2+, Ni2+, Na+ C) possible ions present Ag+, Cu2+, Cd2+ D) possible ions present Ag+, Cu2+, Cd2+, Na+ Answer: B Topic: Section 15.13 Precipitation of Ionic Compounds 90) A solution may contain the following ions Ag+, Cu2+, Mn2+, Ca2+, and Na+. No precipitate formed when 0.10 M NaCl was added but a dark colored precipitate formed when H2S was added to an acidic portion of the solution. After the removal of the solid the solution was made basic and more H2S was added and a dark precipitate again formed. Treatment of the filtrate with (NH4)2CO3 resulted in a white precipitate. If no further tests were made then what conclusions can you draw? A) possible ions present Cu2+, Mn2+, Na+ B) possible ions present Cu2+, Mn2+, Ca2+ C) possible ions present Cu2+, Mn2+, Ca2+, Na+ D) possible ions present Ag+, Cu2+, Mn2+, Ca2+, Na+ Answer: C Topic: Section 15.13 Precipitation of Ionic Compounds 91) Which set of ions precipitate as sulfides? A) Ag+, Pb2+, Mn2+ B) Pb2+, Fe2+, Ca2+ C) Co2+, Ba2+, K+ D) NH4+, Na+, K+ Answer: A Topic: Section 15.13 Precipitation of Ionic Compounds 92) Which pair of ions can be separated by the addition of chloride ion? A) Ag+ and Co2+ B) Cu2+ and Bi3+ C) Pb2+ and Hg22+ D) Ca2+ and Ba2+ Answer: A Topic: Section 15.14 Separation of Ions by Selective Precipitation

20 Copyright © 2012 Pearson Education, Inc.

93) Which pair of ions can be separated by the addition of sulfide ion? A) Ag+ and Cu2+ B) Cu2+ and Bi3+ C) Pb2+ and Ca2+ D) Ca2+ and Ba2+ Answer: C Topic: Section 15.14 Separation of Ions by Selective Precipitation The following pictures represent solutions that contain a weak acid HA and/or its potassium salt KA. Unshaded spheres represent H atoms and shaded spheres represent A- ions. (K+, H3O+, OH-, and solvent H2O molecules have been omitted for clarity.)

94) Which solution has the highest pH? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 95) Which solution has the lowest pH? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 96) Which solution has the largest percent dissociation of HA? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems

21 Copyright © 2012 Pearson Education, Inc.

97) Which of the solutions are buffer solutions? A) (1) and (2) B) (1) and (3) C) (2) and (3) D) (2) and (4) Answer: B Topic: Conceptual Problems 98) Which solution has the greatest buffer capacity? A) (1) B) (2) C) (3) D) (4) Answer: C Topic: Conceptual Problems 99) For which solution(s) is pH = pKa? A) only solution (1) B) only solution (2) C) only solution (3) D) solutions (1) and (3) Answer: D Topic: Conceptual Problems The following pictures represent solutions that contain a weak acid HA (pKa = 5.0) and its potassium salt KA. Unshaded spheres represent H atoms and shaded spheres represent A- ions. (K+, H3O+, OH-, and solvent H2O molecules have been omitted for clarity.)

100) Which solution has the highest pH? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems

22 Copyright © 2012 Pearson Education, Inc.

101) Which solution has the lowest pH? A) (1) B) (2) C) (3) D) (4) Answer: C Topic: Conceptual Problems 102) Which solution has the largest percent dissociation of HA? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 103) Which of these solutions are buffers? A) (1) and (2) B) (1) and (3) C) (1), (2) and (3) D) All are buffer solutions. Answer: D Topic: Conceptual Problems 104) Which solution has the greatest buffer capacity? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 105) For which of these solutions is pH = pKa? A) All have pH = pKa. B) (1), (2) and (3) C) (1) and (4) D) (2) and (3) Answer: C Topic: Conceptual Problems

23 Copyright © 2012 Pearson Education, Inc.

The following pictures represent solutions that contain a weak acid HA (pKa = 5.0) and its potassium salt KA. Unshaded spheres represent H atoms, black spheres represent oxygen atoms, and shaded spheres represent A- ions. (K+, H3O+ initially present, OH- initially present and solvent water molecules have been omitted for clarity.)

106) Which picture represents the equilibrium state of the solution after addition of one H3O+ ion to the solution shown in picture (1)? A) (2) B) (3) C) (4) D) (5) Answer: C Topic: Conceptual Problems 107) Which picture represents the equilibrium state of the solution after addition of one OH- ion to the solution shown in picture (1)? A) (2) B) (3) C) (4) D) (5) Answer: B Topic: Conceptual Problems

24 Copyright © 2012 Pearson Education, Inc.

The following pictures represent solutions at various points in the titration of a weak acid HA with aqueous KOH. Unshaded spheres represent H atoms, black spheres represent oxygen atoms, and shaded spheres represent A- ions. (K+, H3O+ initially present, OH- initially present and solvent water molecules have been omitted for clarity).

108) Which picture represents the solution before the addition of any KOH? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 109) Which picture represents the solution before the equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 110) Which picture represents the solution at the equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: A Topic: Conceptual Problems 111) Which picture represents the solution after the equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: C Topic: Conceptual Problems

25 Copyright © 2012 Pearson Education, Inc.

The following pictures represent solutions at various stages in the titration of a weak diprotic acid H2A with aqueous KOH. Unshaded spheres represent H atoms, black spheres represent oxygen atoms, and shaded spheres represent A2- ions. (K+, H3O+ initially present, OH- initially present and solvent water molecules have been omitted for clarity).

112) Which picture represents the system halfway to the first equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 113) Which picture represents the system at the first equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 114) Which picture represents the system halfway between the first and second equivalence points? A) (1) B) (2) C) (3) D) (4) Answer: A Topic: Conceptual Problems 115) Which picture represents the system beyond the second equivalence point? A) (1) B) (2) C) (3) D) (4) Answer: C Topic: Conceptual Problems

26 Copyright © 2012 Pearson Education, Inc.

116) Which picture represents the system with the highest pH? A) (1) B) (2) C) (3) D) (4) Answer: C Topic: Conceptual Problems 117) Which picture represents the system with the lowest pH? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems Use the graphs below to answer the following questions.

118) What is the characteristic pH-titrant curve for the titration of a strong acid by a strong base? A) A B) B C) C D) D Answer: B Topic: Conceptual Problems 119) What is the characteristic pH-titrant curve for the titration of a strong base by a strong acid? A) A B) B C) C D) D Answer: C Topic: Conceptual Problems 120) What is the characteristic pH-titration curve for the titration of a weak acid by a strong base? A) A B) B C) C D) D Answer: A Topic: Conceptual Problems 27 Copyright © 2012 Pearson Education, Inc.

The following plot shows two titration curves, each representing the titration of 50.00 mL of 0.100 M acid with 0.100 M NaOH.

121) Which point a-d represents the equivalence point for the titration of a strong acid? A) point a B) point b C) point c D) point d Answer: D Topic: Conceptual Problems 122) Which point a-d represents the equivalence point for the titration of a weak acid? A) point a B) point b C) point c D) point d Answer: C Topic: Conceptual Problems 123) At which point a-d is the pKa of the acid equal to the pH? A) point a B) point b C) point c D) point d Answer: A Topic: Conceptual Problems 124) Which points a-d represent the half-equivalence point and the equivalence point, respectively, for the titration of a weak acid? A) points a and b B) points a and c C) points b and d D) points c and d Answer: B Topic: Conceptual Problems 28 Copyright © 2012 Pearson Education, Inc.

125) Which point a-d represents a buffer region? A) point a B) point b C) point c D) point d Answer: A Topic: Conceptual Problems The following plot shows a titration curve for the titration of 1.00 L of 1.00 M diprotic acid H2A with NaOH.

126) A buffer region is indicated by which point(s) a-d? A) point a B) points a and c C) point b D) points b and d Answer: B Topic: Conceptual Problems 127) Which point a-d represents the HX-/X2- buffer region? A) point a B) point b C) point c D) point d Answer: C Topic: Conceptual Problems

29 Copyright © 2012 Pearson Education, Inc.

128) Which point a-d represents the H2X/HX- buffer region? A) point a B) point b C) point c D) point d Answer: A Topic: Conceptual Problems 129) Which point a-d represents the first equivalence point? A) point a B) point b C) point c D) point d Answer: B Topic: Conceptual Problems 130) Which point a-d represents the second equivalence point? A) point a B) point b C) point c D) point d Answer: D Topic: Conceptual Problems 131) Which point a-d represents pKa1? A) point a B) point b C) point c D) point d Answer: A Topic: Conceptual Problems 132) Which point a-d represents pKa2? A) point a B) point b C) point c D) point d Answer: C Topic: Conceptual Problems 133) What is the pH at the first equivalence point? A) pH = pKa1 B) pH = 14 - pKa1 C) pH = (pKa1 + pKa2)/2 D) pH = pKa1 + pKa2 Answer: C Topic: Conceptual Problems 30 Copyright © 2012 Pearson Education, Inc.

134) The following plot shows a titration curve for the titration of 1.00 L of 1.00 M diprotic acid H2A+ with NaOH. Which point a-d represents the isoelectric point?

A) point a B) point b C) point c D) point d Answer: B Topic: Conceptual Problems The following pictures represent solutions of CuS, which may also contain ions other than Cu2+ and S2which are not shown. Gray spheres represent Cu2+ ions and dotted spheres represent S2- ions.

135) If solution (1) is a saturated solution of CuS, which of solutions (2)-(4) are unsaturated? A) only (2) B) only (3) C) only (4) D) (3) and (4) Answer: D Topic: Conceptual Problems

31 Copyright © 2012 Pearson Education, Inc.

136) If solution (1) is a saturated solution of CuS, which of solutions (2)-(4) are saturated? A) (2) B) (3) C) (4) D) None of these Answer: D Topic: Conceptual Problems 137) If solution (1) is a saturated solution of CuS, which of solutions (2)-(4) are supersaturated? A) (2) B) (3) C) (4) D) None of these Answer: A Topic: Conceptual Problems The following pictures represent solutions of AgCl, which may also contain ions other than Ag+ and Clwhich are not shown. Gray spheres represent Ag+ ions and dotted spheres represent Cl- ions.

138) If solution (1) is a saturated solution of AgCl, which of solutions (1)-(4) represents the solution after a small amount of HCl is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 139) If solution (1) is a saturated solution of AgCl, which of solutions (1)-(4) represents the solution after a small amount of HNO3 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: A Topic: Conceptual Problems

32 Copyright © 2012 Pearson Education, Inc.

140) If solution (1) is a saturated solution of AgCl, which of solutions (1)-(4) represents the solution after a small amount of AgNO3 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 141) If solution (1) is a saturated solution of AgCl, which of solutions (1)-(4) represents the solution after a small amount of NH3 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems The following pictures represent solutions of CaCO3, which may also contain ions other than Ca2+ and CO32- which are not shown. Gray spheres represent Ca2+ ions and unshaded spheres represent CO32ions.

142) If solution (1) is a saturated solution of CaCO3, which of solutions (1)-(4) represents the solution after a small amount of NaOH is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 143) If solution (1) is a saturated solution of CaCO3, which of solutions (1)-(4) represents the solution after a small amount of HNO3 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 33 Copyright © 2012 Pearson Education, Inc.

144) If solution (1) is a saturated solution of CaCO3, which of solutions (1)-(4) represents the solution after a small amount of Ca(NO3)2 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: B Topic: Conceptual Problems 145) If solution (1) is a saturated solution of CaCO3, which of solutions (1)-(4) represents the solution after a small amount of K2CO3 is added and equilibrium is restored? A) (1) B) (2) C) (3) D) (4) Answer: D Topic: Conceptual Problems 15.2 Algorithmic Questions 1) What is the hydronium ion concentration in a solution prepared by mixing 50.00 mL of 0.10 M HCN with 50.00 mL of 0.030 M NaCN? Assume that the volumes of the solutions are additive and that Ka = 4.9 × 10-10 for HCN. A) 1.5 × 10- 10 M B) 4.9 × 10-10 M C) 1.6 × 10- 9 M D) 7.0 × 10-6 M Answer: C Topic: Section 15.2 The Common-Ion Effect 2) What is the pH of a solution prepared by mixing 25.00 mL of 0.10 M CH3CO2H with 25.00 mL of 0.0 10 M CH3CO2Na? Assume that the volume of the solutions are additive and that Ka = 1.8 × 10-5 for CH3CO2H. A) 2.87 B) 3.74 C) 4.7 5 D) 5. 74 Answer: B Topic: Section 15.2 The Common-Ion Effect

34 Copyright © 2012 Pearson Education, Inc.

3) What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M NH3 with 5.00 mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb = 1.8 × 10-5 for NH3. A) 8. 25 B) 10.26 C) 10.25 D) 11.13 Answer: C Topic: Section 15.2 The Common-Ion Effect 4) What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine, CH3NH2, with 20.00 mL of 0.10 M methylammonium chloride, CH3NH3Cl? Assume that the volume of the solutions are additive and that Kb = 3.70 × 10-4 for methylamine. A) 10.17 B) 10.57 C) 10.97 D) 11.78 Answer: C Topic: Section 15.2 The Common-Ion Effect 5) What is the pH of a buffer system prepared by dissolving 10.70 grams of NH4Cl and 25.00 mL of 12 M NH3 in enough water to make 1.000 L of solution? Kb = 1.80 × 10-5 for NH3. A) 9.08 B) 9.26 C) 9. 43 D) 11. 32 Answer: C Topic: Section 15.3 Buffer Solutions 6) What is the [CH3CO2-]/[CH3CO2H] ratio necessary to make a buffer solution with a pH of 4.34? Ka = 1.8 × 10-5 for CH3CO2H. A) 0. 39:1 B) 0. 91:1 C) 1. 09:1 D) 2.5:1 Answer: A Topic: Section 15.3 Buffer Solutions 7) What volume of 5.00 × 10–3 M HNO3 is needed to titrate 80.00 mL of 5.00 × 10–3 M Ca(OH)2 to the equivalence point? A) 10.0 mL B) 40.0 mL C) 80.0 mL D) 160. mL Answer: D Topic: Section 15.6 Strong Acid - Strong Base Titrations 35 Copyright © 2012 Pearson Education, Inc.

8) What is the pH of a solution made by mixing 25.00 mL of 0. 100 M HCl with 40.00 mL of 0.100 M KOH? Assume that the volumes of the solutions are additive. A) 0.64 B) 1.64 C) 12.36 D) 13.36 Answer: C Topic: Section 15.6 Strong Acid - Strong Base Titrations 9) What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous formic acid requires 29.80 mL of 0.3567 M NaOH? Ka =1.8 × 10-4 for formic acid. A) 2. 06 B) 5. 48 C) 8. 52 D) 11.94 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 10) What is the approximate pH at the equivalence point of a weak acid-strong base titration if 25 mL of aqueous hydrofluoric acid requires 30.00 mL of 0.400 M NaOH? Ka = 6.76 × 10-4 for HF. A) 1.74 B) 5.75 C) 8.25 D) 12.26 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 11) Formic acid (HCO2H, Ka = 1.8 × 10-4) is the principal component in the venom of stinging ants. What is the molarity of a formic acid solution if 25.00 mL of the formic acid solution requires 29.80 mL of 0.0567 M NaOH to reach the equivalence point? A) 0.0134 M B) 0.0 476 M C) 0.0567 M D) 0. 0676 M Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations 12) What is the pH of the resulting solution if 25.00 mL of 0.10 M acetic acid is added to 10.00 mL of 0.10 M NaOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10-5 for CH3CO2H A) 9. 43 B) 9.08 C) 4.92 D) 4. 57 Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations

36 Copyright © 2012 Pearson Education, Inc.

13) What is the pH of a solution made by mixing 10.00 mL of 0.10 M acetic acid with 10.00 mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. Ka =1.8 × 10-5 for CH3CO2H. A) 5.28 B) 7.00 C) 8.72 D) 10.02 Answer: C Topic: Section 15.7 Weak Acid – Strong Base Titrations 14) What is the pH of a solution made by mixing 30.00 mL of 0.10 M acetic acid with 50.00 mL of 0. 100 M KOH? Assume that the volumes of the solutions are additive. Ka = 1.8 × 10-5 for CH3CO2H. A) 8.26 B) 9.26 C) 11.13 D) 12. 40 Answer: D Topic: Section 15.7 Weak Acid – Strong Base Titrations 15) Sodium hypochlorite, NaOCl, is the active ingredient in household bleach. What is the concentration of hypochlorite ion if 20.00 mL of bleach requires 32.00 mL of 0.500 M HCl to reach the equivalence point? A) 0. 300 M B) 0. 312 M C) 0. 800 M D) 1. 30 M Answer: C Topic: Section 15.8 Weak Base – Strong Acid Titrations 16) What is the pH at the equivalence point of a weak base-strong acid titration if 20.00 mL of NaOCl requires 28.30 mL of 0. 50 M HCl? Ka = 3.0 × 10-8 for HOCl. A) 0.30 B) 3. 18 C) 3.76 D) 4. 03 Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 17) What is the pH of the resulting solution if 45 mL of 0.432 M methylamine, CH3NH2, is added to 15 mL of 0.234 M HCl? Assume that the volumes of the solutions are additive. Ka = 2.70 × 10-11 for CH3NH3+. A) 2.77 B) 4.09 C) 9.91 D) 11.23 Answer: D Topic: Section 15.8 Weak Base – Strong Acid Titrations 37 Copyright © 2012 Pearson Education, Inc.

18) Calculate the Ksp for silver sulfite if the solubility of Ag2SO3 in pure water is 4.6 × 10-3 g/L. A) 3.8 × 10-15 B) 1.5 × 10-14 C) 2.4 × 10-10 D) 4.8 × 10-10 Answer: B Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 19) Calculate the solubility (in g/L) of silver chromate in water at 25°C if the Ksp for Ag2CrO4 is 1.1 × 10-12. A) 3.5 × 10-4 g/L B) 6.5 × 10-5 g/L C) 2.7 × 10-2 g/L D) 3.4 × 10-2 g/L Answer: B Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 20) What is the molar solubility of Mg(OH)2 in a basic solution with a pH of 12.50? Ksp for Mg(OH)2 is 5.61 × 10-12. A) 1.8 × 10- 10 M B) 5.6 × 10- 9 M C) 2.4 × 10-6 M D) 1.1 × 10-4 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 21) Calculate the molar solubility of thallium(I) chloride in 0. 40 M NaCl at 25°C. Ksp for TlCl is 1.7 × 10-4. A) 6.8 × 10-5 M B) 4.2 × 10- 4 M C) 8.2 × 10-3 M D) 1.3 × 10-2 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 22) In which of the following solutions would solid PbBr2 be expected to be the least soluble at 25°C? A) 0.1 M H Br B) 0.1 M NaBr C) 0.1 M CaBr2 D) 0.1 M K NO3 Answer: C Topic: Section 15.12 Factors That Affect Solubility

38 Copyright © 2012 Pearson Education, Inc.

23) What is the molar solubility of AgCl in 0. 20 M NH3? Ksp for AgCl is 1.8 × 10-10 and Kf for Ag(NH3)2+ is 1.7 × 107. A) 1.3 × 10-5 M B) 1.0 × 10- 2 M C) 1.1 × 10- 2 M D) 5.5 × 10-2 M Answer: B Topic: Section 15.12 Factors That Affect Solubility 24) What is the molar solubility of AgCl in 0. 10 M NaCN if the colorless complex ion Ag(CN)2- forms? Ksp for AgCl is 1.8 × 10-10 and Kf for Ag(CN)2- is 1.0 × 1021. A) 0. 050 M B) 0. 10 M C) 0.20 M D) 0.40 M Answer: A Topic: Section 15.12 Factors That Affect Solubility 25) 0.10 M potassium chromate is slowly added to a solution containing 0. 50 M AgNO3 and 0. 50 M Ba(NO3)2. What is the Ag+ concentration when BaCrO4 just starts to precipitate? The Ksp for Ag2CrO4 and BaCrO4 are 1.1 × 10-12 and 1.2 × 10-10, respectively. A) 6.5 × 10-5 M B) 1.3 × 10-4 M C) 3.2 × 10-4 M D) 6.8 × 10-2 M Answer: D Topic: Section 15.13 Precipitation of Ionic Compounds

39 Copyright © 2012 Pearson Education, Inc.

15.3 Short Answer Questions 1) The balanced net ionic equation for the neutralization reaction involving equal molar amounts of HNO3 and KOH is ________. Answer: H3O+(aq) + OH–(aq) ⇌ 2 H2O(l) Topic: Section 15.1 Neutralization Reactions 2) The balanced net ionic equation for the neutralization reaction involving equal molar amounts of HCl and CH3CH2NH2 is ________. Answer: H3O+(aq) + CH3CH2NH2 ⇌ CH3CH2NH3+ + H2O(l) Topic: Section 15.1 Neutralization Reactions 3) What is the equation relating the equilibrium constant Kn for the neutralization of a weak acid with a weak base to the Ka of the acid, the Kb of the base and Kw? K K Answer: Kn = a b Kw Topic: Section 15.1 Neutralization Reactions 4) The neutralization constant Kn for the neutralization of penicillin V (C16H18N2O5S) and erythromycin (C37H67NO13) is 1.3 × 106. The acid dissociation constant Ka for penicillin V is 2.0 × 10-3. What is the base dissociation constant Kb for erythromycin? Answer: 6.5 × 10-6 Topic: Section 15.1 Neutralization Reactions 5) The solution formed upon adding 50.00 mL of 0.10 M NH4Cl to 50.00 mL of 0.10 M NH3 will have a pH that is ________ the pH of the original NH3 solution. Answer: lower than Topic: Section 15.2 The Common-Ion Effect 6) The pH of a solution of HIO3 (Ka = 1.7 × 10-1) and KIO3 is 1.00. What is the molarity of KIO3 if the molarity of HIO3 is 0.025 M? Answer: 0.043 M Topic: Section 15.2 The Common-Ion Effect 7) The pH of a solution of ethylamine, C2H5NH2 (Kb = 6.4 × 10-4) and ethylammium bromide, C2H5NH3Br is 11.00. What is the molarity of C2H5NH3Br if the molarity of C2H5NH2 is 0.025 M? Answer: 0.016 M Topic: Section 15.2 The Common-Ion Effect 8) A buffer prepared by mixing 50.00 mL of 0.10 M HF with 50.00 mL of 0.10 M NaF will have a pH that is ________ 7.0. Answer: less than Topic: Section 15.4 The Henderson-Hasselbalch Equation

40 Copyright © 2012 Pearson Education, Inc.

9) A buffer prepared by mixing equal moles of an acid having Ka = 4.5 × 10–4 and a salt of its conjugate base has a pH = ________. Answer: 3.35 Topic: Section 15.4 The Henderson-Hasselbalch Equation 10) The pH of a 0.150 M formic acid/0.250 M sodium formate buffer = ________? The Ka of formic acid is 1.8 × 10–4. Answer: 3.56 Topic: Section 15.4 The Henderson-Hasselbalch Equation 11) Addition of 0.0125 mol KOH to 150 mL of a 0.150 M formic acid/0.100 M sodium formate buffer results in a pH = ________? The Ka of formic acid is 1.8 × 10–4. Answer: 4.43 Topic: Section 15.4 The Henderson-Hasselbalch Equation 12) Addition of 0.0125 mol HCl to 150 mL of a 0.150 M formic acid/0.100 M sodium formate buffer results in a pH = ________? The Ka of formic acid is 1.8 × 10–4. Answer: 3.89 Topic: Section 15.4 The Henderson-Hasselbalch Equation 13) What is the Ka of the amino acid glycine if it is 75.0% dissociated at pH = 10.08? Answer: 2.5 × 10-10 Topic: Section 15.4 The Henderson-Hasselbalch Equation 14) What is the Ka of the amino acid glutamine if it is 33.0% dissociated at pH = 8.82? Answer: 7.5 × 10-10 Topic: Section 15.4 The Henderson-Hasselbalch Equation 15) The addition of ________ mL of 0.1500 M NaOH is required to titrate 25.00 mL of 0.2250 M HCl to the equivalence point, which occurs at a pH of ________. Answer: 37.50, 7.00 Topic: Section 15.6 Strong Acid - Strong Base Titrations 16) What is the pH of the solution formed when 50 mL of 0.250 M NaOH is added to 50 mL of 0.120 M HCl? Answer: 12.81 Topic: Section 15.6 Strong Acid - Strong Base Titrations 17) What is the pH of the solution formed when 25 mL of 0.173 M NaOH is added to 35 mL of 0.342 M HCl? Answer: 0.89 Topic: Section 15.6 Strong Acid - Strong Base Titrations 18) The half equivalence point in the titration of 0.100 M HCO2H (Ka = 1.8 × 10–4) with 0.250 M NaOH occurs at pH = ________. Answer: 3.74 Topic: Section 15.7 Weak Acid – Strong Base Titrations 41 Copyright © 2012 Pearson Education, Inc.

19) The half equivalence point in the titration of 0.100 M CH3NH2 (Kb = 3.7 × 10–4) with 0.250 M HCl occurs at pH = ________. Answer: 10.57 Topic: Section 15.8 Weak Base – Strong Acid Titrations 20) Selenous acid, H2SeO3 has acid dissociation constants Ka1 = 3.5 × 10–2 and Ka2 = 5 × 10–8. When 25.00 mL of 0.100 M selenous acid is titrated with 0.200 M NaOH the first equivalence point occurs at pH = ________. Answer: 4.2 Topic: Section 15.9 Polyprotic Acid – Strong Base Titrations 21) At 25°C calcium fluoride has a solubility product constant Ksp = 3.5 × 10–11. The solubility of CaF2 at this temperature is ________ mol/L. Answer: 2.1 × 10–4 Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 22) Silver oxalate, Ag2C2O4, has a molar solubility = 1.1 × 10-4 mol/L. Ag2C2O4 has a solubility product Ksp = ________. Answer: 5.4 × 10-12 Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 23) The artist’s pigment cadmium yellow, CdS, has a water solubility of 0.13 g/L. The solubility product of CdS, Ksp = ________. Answer: 8.1 × 10-7 Topic: Section 15.11 Measuring Ksp and Calculating Solubility from Ksp 24) State whether the solubility of Cu(OH)2 will increase or decrease upon the addition of aqueous solutions of a) HCl, b) NaOH, c) NH3. Answer: a) increase, b) decrease, c) increase Topic: Section 15.12 Factors That Affect Solubility 25) CaF2 has Ksp = 3.5 × 10-11. If 25 mL of 8.0 × 10-4 M Ca(NO3)2 is mixed with 75 mL of 4.0 × 10-4 M KF, a precipitate of CaF2 ________ (will, will not) form. Answer: will not Topic: Section 15.13 Precipitation of Ionic Compounds

42 Copyright © 2012 Pearson Education, Inc.