300 May 8, Put all calculations on the examination pages. Do not make any extra marks on the computer answer sheet!!

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1 Name Chemistry (3150: ) FINAL EXAM 120 MINUTES Tuesday, 6:00PM Instructions: 300 May 8, Each student is responsible for following instructions. Read this page carefully. 2. Print your name on this page and on your computer answer sheet. 3. CODE your name (LAST NAME FIRST) on the computer answer sheet using an ordinary (No. 2) pencil. It is very important to code the information correctly!! 4. Put all calculations on the examination pages. Do not make any extra marks on the computer answer sheet!! 5. This exam consists of 60 multiple-choice questions worth 5½ points each. For each multiple-choice question, choose the ONE best or correct answer and write it both on your exam paper and on the computer answer sheet. The computer answer sheet is the only one that will be graded! 6. This exam booklet consists of 10 pages (including this one) and a Periodic Table and Data Sheet. Please check to be sure that you have them all! KEEP YOUR EXAM BOOKLET AND ANSWER SHEET COVERED TO PROTECT THE INTEGRITY OF YOUR WORK!

2 Which of the following aqueous solutions will freeze at the lowest temperature? Note: all of the solutes listed below are completely soluble in water. (a) A 0.10 m solution of KNO 3. (b) A 0.10 m solution of K 2 SO 4. (c) A 0.10 m solution of K 3 PO 4. (d) A 0.10 m solution of K 4 [Fe(CN) 6 ] (Contains the Fe(CN) 4 6 ion.) (e) A 0.10 m solution of sugar. Which of the following alcohols would be least soluble in water? (a) CH 3 OH (b) CH 3 CH 2 CH 2 CH 2 OH (c) CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 OH (d) CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 OH The presence of a non-volatile solute in water will: (a) lower the vapor pressure and freezing point and raise the boiling point. (b) lower the freezing point, vapor pressure, and boiling point. (c) lower the freezing point and raise the vapor pressure and boiling point. (d) raise the boiling point, freezing point, and vapor pressure. (e) lower the vapor pressure and boiling point and raise the freezing point. The following data were collected for the reaction NO 2 (g) + CO (g) NO (g) + CO 2 (g) A study of initial concentration versus initial rate at a certain temperature yields the following data for this reaction: (NO 2 ) o, M (CO) o, M initial rate, M s Which of the following is the correct rate law for this reaction? (a) Rate = k[no 2 ][CO] (d) Rate = k[co] 2 (b) Rate = k[no 2 ][CO] 2 (e) Rate = k (c) Rate = k[no 2 ] 2 If the instantaneous rate of appearance of NO 2 (g) is M/s at some moment in time, what is the rate of disappearance of N 2 O 5 (g) in M/s? 2 N 2 O 5 (g) 4 NO 2 (g) + O 2 (g) (a) M/s (b) M/s (c) M/s (d) M/s (e) M/s A reaction is third-order with respect to a certain reactant. Doubling the concentration of this reactant (holding everything else constant) will cause the rate of the reaction rate to increase by a factor of: (a) 2 (b) 3 (c) 6 (d) 8 (e) 9

3 7. Consider the following reaction: 2 NOCl (g) º 2 NO (g) + Cl 2 (g) K C = Which direction must the reaction shift to reach equilibrium if a reaction container were prepared with (NO) = 0.05 M, (Cl 2 ) = M, and (NOCl) = 1.5 M? (a) right (b) left (c) the reaction is already at equilibrium. 8. Listed here are the three steps in the solution process. Which of these steps is/are exothermic? I. Separation of solute molecules II. Separation of solvent molecules III. Formation of solute-solvent interactions (a) I only. (b) II only. (c) III only. (d) I and II. (e) I, II, and III. 9. Calculate the [H 3 O + ] in a solution of nitric acid with a ph of (a) M (b) 3.78 M (c) M (d) M (e) none of these. 10. Which of the following statements about a reaction at chemical equilibrium is/are true? I. The concentrations of all species in the reaction must be equal. II. The concentrations of all species in the reaction are constant over time. III. The rates of the forward and reverse reactions are equal. (a) I only. (b) II only. (c) III only. (d) II and III. (e) I, II, and III. 11. A change in which of the following to a system at equilibrium would cause the value of the equilibrium constant to change? (a) pressure (b) volume (c) concentration (d) temperature (e) all of the these 12. Which of the following factors affect the effectiveness of collisions between particles in a chemical reaction? (a) orientation of molecules (b) concentration (c) energy of colliding molecules (d) all of these 13. Under which set of conditions would a gas be most soluble in a liquid? (a) high pressure, low temperature (b) low pressure, low temperature (c) low pressure, high temperature (d) high pressure, high temperature 14. Which of the following statements is FALSE? (a) Entropy is a measure of a driving force behind chemical reactions. (b) Entropy is a measure of disorder or randomness. (c) Entropy can be created and destroyed. (d) Entropy is a measure of the number of ways energy can be distributed among the motions of particles. (e) Entropy is a measure of the tendency of energy to become less concentrated.

4 15. Consider the following endothermic reaction at equilibrium: 2 N 2 O 5 (g) º 4 NO 2 (g) + O 2 (g) K C = Which of the following would cause an increase in the equilibrium concentration of NO 2? I. addition of N 2 O 5 II. decrease in pressure III. increase in temperature IV. addition of O 2 (a) I only. (b) I and II only. (c) IV only. (d) I, II, and III. (e) I, II, III, and IV. What would be the value of K C for the following reaction? (See previous question.) 4 NO 2 (g) + O 2 (g) 2 N 2 O 5 (g) (a) (b) (c) 1 (d) 1 (e) none of these Chemical thermodynamics predicts (correctly) that materials made of wood, paper, metal, plastic, leather, and rubber react with oxygen in the atmosphere and decompose at 25 o C and 1 atm pressure. Which of the following is responsible for the fact that these reactions are very slow under these conditions? (a) entropy (b) enthalpy (c) internal energy (d) activation energy (e) potential energy The following equation represents the reaction that occurs when fuel oil and ammonium nitrate, a component of fertilizer, react explosively. This kind of explosion destroyed the Murrah Federal Building in Oklahoma City, Oklahoma in NH 4 NO 3 (s) + C 17 H 36 (l) 52 N 2 (g) + 17 CO 2 (g) H 2 O (g) Using positional entropy arguments, the S sys for this process would be: (a) positive (b) negative (c) zero (d) It is impossible to tell. The following equation was derived for the [H 3 O + ] in a solution of a weak acid in water: [H O ] = K C + o 3 A acid 20. What assumptions were included in the derivation of this formula? I. there are no OH ions present in the solution. II. the auto-ionization of water is negligible. III. [H 3 O + ] is much smaller than C. o acid (a) I only. (b) II only. (c) III only. (d) II and III only. (e) I, II, and III. Formic acid (HCOOH) is a weak acid with K A = Acetic acid (CH 3 COOH) is a weak acid with K A = Which of the following is/are FALSE? I. Formate ion (HCOO ) is a stronger base than acetate ion (CH 3 COO ). II. A 0.10 M solution of formic acid has a larger percent dissociation than a 0.10 M solution of acetic acid. III. Formic acid is a stronger acid than acetic acid. (a) I only. (b) II only. (c) III only. (d) I and II only. (e) II and III only.

5 Addition of formic acid to a sodium formate solution at equilibrium will cause: (a) no change in H 3 O + concentration. (b) H 3 O + concentration to decrease. (c) H 3 O + concentration to increase. (d) concentrations of all species to increase. (e) concentrations of all species to decrease. Consider the following reactions: Ag + (aq) + 2 NH 3 (aq) º Ag(NH 3 ) + 2 (aq) K 1 = AgCl (s) º Ag + (aq) + Cl (aq) K 2 = What is the value of the equilibrium constant for the following reaction? AgCl (s) + 2 NH 3 (aq) º Ag(NH 3 ) + 2 (aq) + Cl (aq) (a) K 1 K 2 (b) K 1 K 2 (c) K 1 K 2 (d) K 1 + K 2 (e) none of these. Calculate the ph of a buffer prepared by mixing 0.10 mol of sodium formate (HCOONa) and 0.10 mol of formic acid (HCOOH) in 1.0 L of solution. [HCOOH: K A = ] (a) (b) 3.44 (c) 4.05 (d) 5.31 (e) none of these Would a solution of ammonium bromide (NH 4 Cl) be acidic, basic, or neither? K B (NH 3 ) = (a) acidic (b) basic (c) neither acidic nor basic A reaction has a value of G o = kj. Which of the following must be TRUE about this reaction? I. The reaction is spontaneous at standard conditions. II kj of work must be done on the reaction to make it occur. III. The equilibrium constant of this reaction is greater than 1. (a) I only. (b) II only. (c) I and II only. (d) I and III only. (e) I, II, and III. A reaction has a value of G o = kj. How long (in s) would the reaction take to reach equilibrium? (a) 83.9 s (b) s (c) s (d) 42.0 s (e) It is impossible to tell. Which of the following sets of conditions is consistent with a reaction that would be spontaneous at HIGH temperatures and nonspontaneous at LOW temperatures? (a) H positive, S negative (b) H positive, S positive (c) H negative, S positive (d) H negative, S negative CHEM 153 Final Exam 2

6 The ph at the equivalence point of the titration is not = 7.0 because: (a) at the equivalence point, there is excess OH present. (b) at the equivalence point, the solution contains the conjugate base of the weak acid. (c) at the equivalence point, the weak acid becomes a stronger base than water. (d) This titration contains some experimental error. The ph of an equivalence point should be 7. Which of the following might increase the solubility of a salt above the molar solubility estimated from the K SP value? (a) formation of ion pairs (b) formation of complex ions (c) reaction of ions with water (d) all of the above The solubility product constant for cobaltic hydroxide, Co(OH) 3, is What is the solubility of cobaltic hydroxide in a solution buffered at ph 9.00? (a) M (b) M (c) M (d) M (e) none of these CHEM 153 Final Exam 3

7 The enthalpy of vaporization of carbon tetrachloride is 32.6 kj/mol. The value of S o for the vaporization of carbon tetrachloride is 95.0 J/mol K. Use this information to estimate the boiling point of carbon tetrachloride. (a) 0.34 K (b) 2.91 K (c) 343 K (d) 616 K (e) 3097 K Consider the following chemical reaction at equilibrium: H 2 (g) + I 2 (s) º 2 HI (g) Which of the following statements is/are TRUE? I. Adding solid iodine would change the value of G. II. Adding solid iodine would change the value of G o. III. Adding HI gas to the equilibrium mixture would make the value of G decrease. IV. The value of G is zero. (b) I only. (b) IV only. (c) I and III only. (d) I and IV only. (e) I, III, and IV. Calculate the cell potential in V at 25 o C for the galvanic cell shown in the diagram below. Note that zinc sulfate is a soluble salt. (a) 0.50 V (b) V (c) V (d) V (e) V Which of the following metals could be used to prevent the corrosion of a buried steel fuel tank using cathodic protection? (a) Ag (b) Mg (c) Sn (d) Cd (e) Pb Which of the following reactions IS is a redox reaction? (a) H 3 PO 4 (aq) + 3 NaOH (aq) Na 3 PO 4 (aq) + 3 H 2 O (l) (b) NH 3 (g) + H 2 O (l) º NH + 4 (aq) + OH (aq) (c) AgF (s) º Ag + (aq) + F (aq) (d) H 2 (g) + O 2 (g) 2 H 2 O 2 (l) (e) 2 NO 2 (g, nitrogen dioxide ) º N 2 O 4 (g, dinitrogen tetroxide ) CHEM 153 Final Exam 4

8 Questions deal with the following galvanic cell which involves the following reduction potentials: Ag + (aq) + e Ag (s) E o = V Cr 3+ (aq) + 3 e Cr (s) E o = 0.74 V 36. Calculate E o for the following galvanic cell: (a) 1.54 V (b) 0.06 V (c) V (d) +1.54V (e) none of these 37. Which of the following describes what happens to the concentrations of Cr 3+ and Ag + and the masses of the electrodes as this galvanic cell generates an electrical current spontaneously at 25 o C? Concentration of Cr 3+ Concentration of Ag + Mass of Ag electrode Mass of Cr electrode (a) decreases decreases increases increases (b) decreases increases decreases increases (c) increases decreases increases decreases (d) increases increases decreases decreases (e) increases decreases no change no change Which of the following statements about a salt bridge in a galvanic cell is FALSE? (a) The salt bridge contains an electrolyte solution in a gelatinous matrix. (b) The salt bridge does not allow the ions present in the two half-cells to mix extensively. (c) The wire must be connected to the salt bridge in order for the salt bridge to be able to maintain electrical neutrality in the half-cells. (d) Anions in the salt bridge flow toward the half-cell where oxidation occurs. (e) Ions from the electrolyte in the salt bridge flow into each half-cell to maintain electrical neutrality in the half-cells. What is the relationship between the following structures? (a) linkage isomers (b) geometric isomers (c) enantiomers (d) coordination isomers (e) identical CHEM 153 Final Exam 5

9 40. Which of the following forms of radiation would have the greatest ionizing ability? (a) alpha particles. (c) beta particles. (e) gamma rays (b) neutrons. (d) positrons. 41. Which of the following radioactive nuclides would be most appropriate for verifying a claim that an aged wine was bottled in 1953? (a) carbon-14, t 1/2 = 5730 years (d) potassium-40, t 1/2 = 1.3 billion years (b) thallium-201, t 1/2 = 73 hours (e) tritium (hydrogen-3), t 1/2 = 12.3 years (c) chromium-51, t 1/2 = 27.8 days 42. Which of the following parts of a fission nuclear reactor slows down but does not absorb neutrons? (a) fuel rods (c) control rods (e) containment system (b) moderator (d) coolant 43. The instrumentation in a PET scan detects which of the following? (a) positrons. (c) neutrons. (e) beta particles. (b) alpha particles. (d) gamma rays. 44. A fresh sample containing grams of cobalt-60 today would have how much cobalt-60 remaining after years? The half-life of cobalt-60 is 5.25 years. (b) grams. (d) 0.0 grams (no cobalt-60 remaining). (c) 50.0 grams. (e) It is impossible to tell without additional information. (d) 25.0 grams. 45. Why does natural unpolluted rainwater has a ph of ~5.6? (a) 5.6 is the neutral point of the ph scale. (b) Carbon dioxide is dissolved in the rainwater (c) Salts from evaporated seawater are dissolved in the rainwater. (d) There are no hydroxide ions in rainwater. (e) It is impossible to explain why. 46. According to the diagram, uranium nuclei can become more stable nuclei by what process? (a) fission. (b) fusion. (c) osmosis. (d) oxidation. (e) hybridization. CHEM 153 Final Exam 6

10 Identify the Lewis Base in the following complex ion formation reaction: Co :OCN [Co(OCN) 4 ] (a) Co 3+ (b) OCN (c) [Co(OCN) 4 ] What is the coordination number of the metal ion in the following coordination compound: [Fe(o-phen) 2 (NH 3 ) 2 ]Cl 2? (Note: o-phen is a bidentate ligand.) (a) 3 (b) 4 (c) 5 (d) 6 (e) 8 What is the oxidation number of the metal ion in the coordination compound in the previous question? (a) 3 (b) 2 (c) 0 (d) +2 (e) +3 Which of the following ions should be colorless in solution? (a) Cu 2+ (b) Fe 2+ (c) Zr 4+ (d) Mo 2+ (e) Cr 3+ EDTA 4 is a hexadentate ligand. Which of the following must be true? (a) EDTA 4 contains six donor atoms. (b) The coordination number of Co in [Co(EDTA)] 2 is 6. (c) When EDTA 4 forms a complex with a transition metal, the geometry around the transition metal is octahedral. (d) All of the above are true. If 192 Ir undergoes electron capture, the product is: (a) 192 Os (b) 192 Pt (c) 188 Re (d) 190 Re (e) none of these are correct What nuclide is formed after Po undergoes one alpha decay and one beta decay? (a) 214 Bi (b) 210 Hg (c) 218 Rn (d) 214 Tl (e) none of these are correct 1.50 liters of a solution contain 147 g of HClO 4. What is the molarity of the solution? (a) M (b) 1.46 M (c) 1.86 M (d) 2.69 M (e) 2.80 M How many of the items below are important concerns for the use of radioactive nuclides in medical applications? short half-life stable decay products small doses localization in body penetrating ability (a) 1 (b) 2 (c) 3 (d) 4 (e) 5 Which of the following is FALSE? (a) Internal Energy ( E) is a state function. (b) Temperature (T) is a state function. (c) Entropy ( S) is a state function. (d) Wyoming (WY) is a state. (e) Heat (q) is a state function. CHEM 153 Final Exam 7

11 57. Which of the following diagrams represents a snapshot of a very small portion of a beaker containing a weak acid, HA, dissolved in water? HA (aq) + H 2 O (l) º H 3 O + (aq) + A (aq) Note that the solvent molecules (i.e., H 2 O) are not shown for clarity Which of the following would have the largest buffer capacity toward addition of small amounts of acid or base? (Benzoic acid is a weak acid.) (a) a solution 0.80 M in benzoic acid and 0.10 M in sodium benzoate (b) a solution 0.80 M in benzoic acid and 0.80 M in sodium benzoate (c) a solution 0.80 M in HCl and 0.80 M in KCl (d) a solution 0.80 M in benzoic acid and 0.40 M in sodium benzoate (e) a solution 0.40 M in benzoic acid and 0.80 M in sodium benzoate In class, you observed a demonstration starting with a pale blue solution of Cu 2+ ions. Addition of aqueous ammonia (NH 3 ) produced a dark solid precipitate. Addition of more ammonia caused the precipitate to dissolve, producing a deep blue solution. What is the best explanation for the precipitate dissolving? (a) Ammonia is a common ion. (b) The solution of copper ions became supersaturated. (c) A complex ion was formed. (d) Ammonia acts as a Bronsted base but as a Lewis acid. (e) We did not wait long enough for the solid to dissolve in the first place. CHEM 153 Final Exam 8

12 60. The graph below shows the catalyzed and uncatalyzed reaction pathways for the same reaction. Which of the following correctly matches the labels to the labeled graph regions? Region A Region B Arrow C Arrow D Arrow E (a) products transition state E A (uncatalyzed (b) reactants transition state E A (uncatalyzed (c) reactants products E A (uncatalyzed (d) transition state reactants E A (uncatalyzed (e) transition state reactants E A (catalyzed H RXN (or E RXN ) H RXN (or E RXN ) H RXN (or E RXN ) H RXN (or E RXN ) H RXN (or E RXN ) E A (catalyzed E A (catalyzed E A (catalyzed E A (catalyzed E A (uncatalyzed B C energy A E D reaction progress 61. Compound A 2 B 4 decomposes at high temperature into AB 3 and AB: A 2 B 4 AB 3 + AB A student collects concentration data for the decomposition over time. If the reaction is second order in Compound A 2 B 4, which of the following plots should give a straight line? (a) [A 2 B 4 ] vs time (b) ln[a 2 B 4 ] vs time (c) 1/[A 2 B 4 ] vs time (d) [A 2 B 4 ] 2 vs time (e) none of these. CHEM 153 Final Exam 9

13 62. In solution, cobalt (II) ions form the [Co(H 2 O) 6 ] 2+ complex ion. How many unpaired electrons are there in this complex ion? Note: H 2 O is a weak-field ligand. (a) 0 (b) 1 (c) 2 (d) 3 (e) 4 END OF EXAM Check to see that you have entered 62 answers on your scan sheet. Proofread your work. You may take this exam booklet with you but you must return your scan sheet before leaving the room! CHEM 153 Final Exam 10