CHEM 102 Winter 18 Final Exam (A) Questions and Answers,100% CORRECT

CHEM 102 Winter 18 Final Exam (A) Questions and Answers Potentially useful data: x  1 atm = 760 torr = 760 mm Hg 2 a [A]t = – kt + [A]o ΔG° = ΔH° – T ΔS° ln[A]t = – kt + ln[A]o ΔG = ΔG° + RT ln Q 1/[A]t = kt +1/[A]o ΔG° = – RT ln K First order half-life: t1/2 = ln2 / k ΔG° = – nFE° pH  pKa  log base acid  E  E  R T ln Q n F R = 8.314 J mol-1 K-1 F = 96500 C/mol e- 1. Please choose the letter “A” as your answer for this question. 2. How many hydrogen atoms would be present in methylbenzene? a) 6 b) 8 c) 10 d) 12 e) 14 3. Which of the following solids has the highest standard entropy at 25 oC? a) LiF b) LiI c) LiCl d) LiBr e) All have the same standard entropy. Page 1 of 14 4. Which of the following would dissolve CuI(s) the most? a) 0.6 M MgI2(aq) b) distilled water c) 0.1 M CuNO3(aq) d) 1 M NaI(aq) e) 0.1 M NaI(aq) 5. Consider a buffer solution of a weak acid, HA. When will the buffer be most effective in keeping the pH around a certain value? a) [A- ] = [HA] b) [HA] = [H3O+] c) [H3O+] = [OH-] d) [OH-] = [HA] e) [H3O+] = [HA]/[A- ] 6. Determine the reaction rate with respect to [H2] in the ammonia formation: N2 (g) + 3 H2 (g) → 2 NH3 (g) a) rate = + 3Δ[H2]/Δt b) rate = - 3Δ[H2]/Δt c) rate = + 1/3 Δ[H2]/Δt d) rate = - 1/3 Δ[H2]/Δt e) Not enough info to determine. 7. Estimate the [H3O+] in a buffer that consists of 0.30 M HCOOH (Ka = 1.7 × 10–4) and 0.20 M HCOONa. a) 1.1 × 10–4 M b) 2.6 × 10–4 M c) 4.3 × 10–4 M d) 6.7 × 10–5 M e) 7.6 × 10–5 M 8. Which substance exhibits ONLY London dispersion intermolecular forces between its molecules? a) HF b) SiCl4 c) PF3 d) OF2 e) CH3Cl Use the chemical structure A given below to answer questions 9 and 10: CH3 H3C C H H C CH CH2 CH3 A 9. What is the correct name of compound A? a) 4,5-dimethylpentane b) 4,5-dimethyl-2-pentene c) 3-methyl-4-hexene d) 4-methyl-2-hexene e) 2-methyl-3-pentene 10. Which statement is FALSE about compound A? a) Methylcyclohexane is a structural isomer of compound A. b) Compound A can be used as a monomer for addition polymerization. c) Compound A is a hydrocarbon. d) There are two possible, distinct 3-D orientations of the C-H bonds around the C=C bond. e) The addition of two hydrogen atoms to compound A would convert this compound into an alkyne. 11. Use the graph below to choose the correct answer: At a constant pressure of 1 atmosphere, the transition from Phase II to Phase III is a) an exothermic process in which solid molecules lose energy. b) an exothermic process in which gas molecules lose energy. c) an endothermic process in which solid molecules gain energy. d) an endothermic process in which liquid molecules gain energy. e) an endothermic process in which gas molecules absorb energy. 12. Consider the following reaction: CO2 (g) + C (graphite) 2 CO (g) A reaction mixture containing 0.56 atm CO2 and 0.32 atm CO is heated to a certain temperature. Estimate the equilibrium pressure of CO, if the equilibrium constant, Kp, at that temperature is 2.25. a) 0.83 atm b) 0.31 atm c) 0.26 atm d) 0.58 atm e) 0.42 atm 13. Determine the molar solubility of Al(OH)3 in a solution containing 0.05 M AlCl3. Ksp for Al(OH)3 is 1.3 × 10-33. a) 2.6 × 10-9 M b) 5.2 × 10-31 M c) 9.9 × 10-12 M d) 1.04 × 10-29 M e) 6.5 × 10-35 M 14. Which of the following monomers can be used to make a condensation polymer with an amide linkage? I. a diol (or dialcohol) and a dicarboxylic acid II. a diamine and a dicarboxylic acid III. a diol and a diamine IV. an amino acid (that is, a compound containing both an -NH2 and a -COOH as functional groups) a) only II b) only I c) only IV d) both II and IV e) both I and II 15. Estimate the number of grams of NaHCO3 in 150.0 g of a solution that is 2.25% NaHCO3 by weight. a) 1.50 g b) 66.7 g c) 3.38 g d) 225 g e) 338 g 16. Sulfur dioxide combines with oxygen to form sulfur trioxide in an exothermic reaction, according to the chemical equation below. Which change (or changes) will shift the equilibrium towards reactants? 2 SO2 (g) + O2 (g) ⇌ 2 SO3 (g) a) increasing the pressure b) raising the temperature c) adding O2 (g) d) compressing the mixture e) both a) and b) 17. Calculate the concentration of OH⁻ in a solution that contains 3.9 × 10-4 M H3O+ at 25 oC. Identify the solution as acidic, basic or neutral. a) 2.6 × 10-11 M, acidic b) 2.6 × 10-11 M, basic c) 3.9 × 10-4 M, neutral d) 2.7 × 10-2 M, basic e) 2.7 ×10-2 M, acidic 18. Consider the overall reaction below for an electrochemical cell with this temperature is and the cell is . o cell = 2.350 V at 200.0 °C. G° at a) + 226.8 kJ; spontaneous 2 Na (l) + FeCl2 (s)  2 NaCl (s) + Fe (s) b) + 453.5 kJ; non-spontaneous c) – 226.8 kJ; non-spontaneous d) – 453.5 kJ; spontaneous e) – 453.5 kJ; at redox equilibrium 19. Which of the following substances is least likely to dissolve in water? a) HCl b) CH3OH c) CH3(CH2)7OH d) NaCl e) All of the above would be very soluble in water. 20. Which substance below has the highest vapor pressure at the same temperature? a) CH3-OH (l) b) CH3-O-CH3 (l) c) H2O (l) d) C20H44 (l) e) CH3-COOH (l) 21. The cell notation for a voltaic cell constructed with copper and silver is shown below. Cu (s) | Cu2+ (aq) || Ag+ (aq) | Ag (s) Which process occurs at the cathode? a) Ag+ (aq) + e–  Ag (s) b) Cu2+ (aq) + 2e–  Cu (s) c) Ag (s)  Ag+ (aq) + e– d) Cu (s)  Cu2+ (aq) + 2e– e) Cu (s) + 2 Ag+ (aq)  Cu2+ (aq) + 2 Ag (s) 22. Which statement about fuel cells is TRUE? a) In a fuel cell, reactants are constantly replenished from an external source. b) Fuel cells are based on non-spontaneous redox reactions. c) In a hydrogen-oxygen fuel cell, the hydrogen undergoes reduction. d) Fuel cells are not electrochemical cells. e) A functional fuel cell must have a negative Eocell. 23. A solution containing the equilibrium amount of dissolved solute is called . a) unsaturated b) concentrated c) supersaturated d) saturated e) None of the above. 24. Which of the following aqueous mixtures can function as a buffer solution? a) H2CO3 and NaHCO3 b) NaH2PO4 and Na2HPO4 c) NH3 and (NH4)2SO4 d) CH3CH2COOH and CH3CH2COO-K+ e) All of the above. 25. Consider the chemical equation below. Which molecule is reduced? CH4 + O2 → CO2 + H2O a) O2 b) CO2 c) H2O d) CH4 e) None of the above. This is not a redox process. 26. The cell shown below has Eocell = + 1.41 V. Al(s) | Al3+(aq) || Ni2+(aq) | Ni(s) The concentration of Al3+(aq) is 0.050 M and the concentration of Ni2+(aq) is 2.0 M. Estimate the cell potential at 25 oC. a) +1.34 V b) +1.44 V c) -1.41 V d) +1.38 V e) +1.48 V 27. The second-order decomposition of HI has a rate constant of 1.80 × 10-3 M-1s-1. If the initial concentration of HI is 4.78 M, estimate [HI] after 27.3 s. a) 3.87 M b) 0.258 M c) 4.55 M d) 2.20 M e) 2.39 M 28. Which aqueous solution has the lowest pOH? -5 a) 0.01 M HC2H3O2 (Ka =1.8 × 10 ) -4 b) 0.01 M HNO2 (Ka =4.5 × 10 ) -8 c) 0.01 M HClO (Ka =3.0 × 10 ) -4 d) 0.01 M HF (Ka =6.8 × 10 ) e) pOH cannot be estimated for acidic solutions, only for basic ones. 29. If a catalyst is added to a chemical equilibrium, the yield of the products will , and the time required for the system to reach equilibrium will . a) increase; decrease b) decrease; stay the same c) increase; stay the same d) stay the same; decrease e) decrease; decrease 30. What value could indicate a pH at the equivalence point for a weak acid – strong base titration? a) 6.8 b) 7.0 c) 5.5 d) 8.2 e) 12 31. A 25.0 mL sample of CH3COOH(aq) is titrated with a 0.175 M NaOH(aq). When 37.5 mL of the base are added, the equivalence point is reached. Estimate the concentration of CH3COOH(aq). a) 0.119 M -4 b) 1.83 × 10 M c) 0.175 M d) 0.365 M e) 0.263 M 32. Consider a reaction that has a negative ΔH and a positive ΔS. Which statement is true? a) This reaction will be spontaneous only at high temperatures. b) This reaction will be spontaneous at all temperatures. c) This reaction will be non-spontaneous at all temperatures. d) This reaction will be non-spontaneous only at high temperatures. e) It is not possible to determine without more information. 33. Consider the titration of acetic acid, CH3COOH, with sodium hydroxide, NaOH, that you performed in the lab. What happens halfway to the equivalence point? a) pH = pKa b) pH/2 = pKa c) Half the acid has been converted to its conjugate base. d) The end point equals the equivalence point. e) both a) and c) 34. Which action would increase the solubility of Mg(OH)2 in an aqueous solution at 25 °C? a) increasing the pH of the solution b) adding an aqueous solution of MgCl2 c) removing a small amount of Mg(OH)2 d) adding an aqueous solution of a strong base e) decreasing the pH of the solution 35. The reaction rate generally decreases when . a) the temperature of reaction increases b) the activation energy increases c) the surface contact area of reactants decreases d) both b) and c) e) both a) and b) 36. The rate law for the reaction below A + 2B → P was found to be: rate = k[A][B]2 If the concentration of B increases from x to 3x, while [A] does not change, the rate of reaction will . a) triple b) increase by a factor of 6 c) stay the same d) double e) increase by a factor of 9 37. Use the experimental data below to determine the rate law for the following reaction: S O2 + 3 I–(aq)  2SO2 + I3– Experiment [S O 2-] [I–] Initial Rate 2 8 0 0 a) rate = k[S2O82-][I-]3 b) rate = k[S2O82-] c) rate = k[S2O82-]2[I-]2 d) rate = k[I-] e) rate = k[S2O82-][I-] 38. Identify the correct expression for the equilibrium constant associated with the chemical equation below: 2 Cu2+ (aq) + Sn2+ (aq) ⇌ Sn4+ (aq) + 2 Cu+ (aq) a) b) c) d) e) None of the above. 39. Which statement about entropy is TRUE? a) Entropies of gases are usually much smaller than those of liquids. b) Entropy usually increases when two pure liquids mix to form a solution. c) Entropy decreases when a solid melts. d) The entropy of a pure substance in a given state decreases as the temperature rises. e) None. All of the above statements are false. 40. Which acid will generate the weakest conjugate base in aqueous solution? a) dihydrogen phosphate (Ka = 2.9 × 10–7) b) acetic acid (Ka = 1.8 × 10–5) c) benzoic acid (Ka = 6.3 × 10–5) d) formic acid (Ka = 1.8 × 10–4) e) nitrous acid (Ka = 4.6 × 10–4) 41. Which situation below would NOT favor miscibility? a) The solute-solvent interactions are stronger than the solute-solute and the solvent-solvent interactions. b) The solute-solute interactions are weaker than the solute-solvent interactions. c) The solute-solvent interactions are weaker than the solute-solute and the solvent-solvent interactions. d) The solute-solvent interactions are stronger than the solvent-solvent interactions. e) All of the above would favor miscibility. 42. Which of the following is a conjugate acid-base pair? a) H3O+ and OH- b) NH4+ and NH2- c) H2SO4 and HSO4- d) H3PO4 and PO 3- e) All of the above. 43. What is the pH of 0.1 M HCl(aq)? a) 0.05 b) 1 c) 10-1 d) 10-2 e) 2.3 44. The composition analysis of a gas-phase reaction mixture (for which Kp = 10) indicates a value of Q = 15. At equilibrium, . a) Kp > 10 b) Q = 10 c) Q = 25 d) Kp < 10 e) Q = 15 45. Which of the following plots could be used to determine if a reaction is first order? a) ln(k) versus time b) 1/[reactant] versus time c) [reactant] versus time d) ln(k) versus 1/temperature e) ln[reactant] versus time 46. Consider the following reaction: 2 A + B + 2 C → P If the reaction is zero order with respect to A, second order with respect to B, and first order with respect to C, what are the units of measure for the rate constant? Assume the time measured in seconds. a) M-2 s-1 b) M-1 s-1 c) s-1 d) M-3 s-1 e) M s-1 47. When a diprotic acid dissociates in an aqueous solution, the value of Ka1 will be the value of Ka2 because . a) smaller than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule b) larger than; it is easier to remove a hydrogen ion from a neutral molecule than from an anion c) larger than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule d) the same as; both hydrogen ions are bonded to the same anion e) smaller than; it is easier to remove a hydrogen ion from a neutral molecule than from an anion 48. Which of the following is NOT conserved in a chemical reaction? a) matter b) energy c) entropy d) atoms identity e) total number of electrons 49. Which is the weakest acid? a) HOCl b) HOI c) HOBr d) All of the above acids are very strong, since they contain O atoms. e) All of the above acids have the same strength, since they have similar molecular formulas. 50. What would be the standard cell potential for a spontaneous electrochemical cell constructed with the two metals below? Cu2+(aq) + 2e–  Cu(s) E° = 0.34 V Sn4+(aq) + 2e–  Sn2+(aq) E° = 0.13 V a) 0.47 V b) 0.21 V c) – 0.21 V d) – 0.47 V e) 0.42 V 51. Knowing that the equilibrium constant for the reaction below H2 (g) + Br2 (g) ⇌ 2 HBr (g) is Kc = 3.8 × 104, determine the equilibrium constant for the following reaction: 4 HBr (g) ⇌ 2 H2 (g) + 2 Br2 (g) a) 1.9 × 104 b) 5.1 × 10-3 c) 6.9 × 10-10 d) 2.6 × 10-5 e) 1.6 × 103 chem102w18_final exam A Answer Section MULTIPLE CHOICE 1. ANS: A PTS: 0 2. ANS: B PTS: 1 3. ANS: B PTS: 1 4. ANS: B PTS: 1 5. ANS: A PTS: 1 6. ANS: D PTS: 1 7. ANS: B PTS: 1 8. ANS: B PTS: 1 9. ANS: D PTS: 1 10. ANS: E PTS: 1 11. ANS: D PTS: 1 12. ANS: A PTS: 1 13. ANS: C PTS: 1 14. ANS: D PTS: 1 15. ANS: C PTS: 1 16. ANS: B PTS: 1 17. ANS: A PTS: 1 18. ANS: D PTS: 1 19. ANS: C PTS: 1 20. ANS: B PTS: 1 21. ANS: A PTS: 1 22. ANS: A PTS: 1 23. ANS: D PTS: 1 24. ANS: E PTS: 1 25. ANS: A PTS: 1 26. ANS: B PTS: 1 27. ANS: A PTS: 1 28. ANS: C PTS: 1 29. ANS: D PTS: 1 30. ANS: D PTS: 1 31. ANS: E PTS: 1 32. ANS: B PTS: 1 33. ANS: E PTS: 1 34. ANS: E PTS: 1 35. ANS: D PTS: 1 36. ANS: E PTS: 1 37. ANS: E PTS: 1 38. ANS: B PTS: 1 39. ANS: B PTS: 1 40. ANS: E PTS: 1 41. ANS: C PTS: 1 42. ANS: C PTS: 1 43. ANS: B PTS: 1 44. ANS: B PTS: 1 45. ANS: E PTS: 1 46. ANS: A PTS: 1 47. ANS: B PTS: 1 48. ANS: C PTS: 1 49. ANS: B PTS: 1 50. ANS: B PTS: 1 51. ANS: C PTS: 1