Chemistry 112 Name Final Exam Form A Section May 4, 2015 Signature IMPORTANT: On the scantron (answer sheet), you MUST clearly fill your name, your student number, section number, and test form (white cover = test form A; yellow cover = test form B). Use a #2 pencil. There are 40 questions on this exam. Check that you have done all of the problems and filled in the first 40 bubbles on the scantron. The maximum score on this exam is 40 points. Your score will be reported in percents (max 100%). Exam policy This cover sheet must be signed and handed in with your answer sheet for your exam to count. Calculators with text-programmable memory are not allowed. Relevant data and formulas, including the periodic table, are attached at the end of this exam. Your grade will be based only on what is on the scantron form. The answer key will be posted on the web after the exam (under News). Hints As you read the question, underline or circle key words to highlight them for yourself. Avoid errors from "mis-reading" the question. Pay attention to units and magnitudes (decimal places) of numbers obtained from calculations. There is no penalty for guessing.
CHEMISTRY 112 EXAM 4 May. 4, 2015 FORM A 1. What is the bond order of the heteronuclear diatomic ion NO +? Use the M.O. Energy diagram below. A. 1 B. 1.5 C. 2 D. 2.5 E. 3 \ 2. Consider the following kinetic data for the reaction: A + 2 B products Experiment [A], M [B], M Initial Rate, M/s 1 0.10 0.10 7.00 10 5 2 0.20 0.10 2.80 10 4 3 0.20 0.20 2.80 10 4 The rate law for the reaction is: A. k [A] [B] B. k [A] 2 [B] C. k [A] 1/2 [B] D. k [A] [B] 2 E. k [A] 2
3. The most probable mode of decay of 40 Cl is A. α emission B. β emission C. positron emission D. neutron emission E. electron capture 4. Which of the following combinations can make a buffer? A. HNO 3 + NaNO 3 B. KCl + HCl C. NaNO 2 + NaBr D. HF + KF E. NaOH + NaCl 5. Which element could be used to dope silicon to create a p-type semiconductor? A. B B. P C. C D. Ge E. F 6. Which one of the following statements is true regarding semiconductors? A. Intrinsic semiconductors have an average of 5 electrons per atom. B. An example of an intrinsic semiconductor is GaTe. C. An example of an n-type semiconductor is Si doped with P. D. Semiconductors have no band gap; electrons are free to move between the valence band and conduction band with little to no energy needed. E. A p-type semiconductor consists of an intrinsic semiconductor that is intentionally doped with an impurity that contains more than 4 valence electrons.
----------------------------------------------------------------------------------------------------------- 7. Band theory explains the conductive properties of materials. Match each MO band theory pictured below to the proper material: A. Conductor (metal) Semiconductor Insulator B. Insulator Semiconductor Conductor (metal) C. Conductor (metal) Insulator Semiconductor D. Insulator Conductor (metal) Semiconductor E. Semiconductor Insulator Conductor (metal) 8. Which of the following substances does not exist in the indicated solid type? A. graphite covalent network B. SiO 2 molecular C. Na metallic D. KI ionic E. diamond covalent network 9. What is ΔG o for the base hydrolysis of methylamine (CH 3 NH 2 ) in an aqueous solution at 25 o C? K b (CH 3 NH 2 ) = 4.4 10 4 A. 19.1 kj/mol B. 1.61 kj/mol C. 8.32 kj/mol D. 1.57 10 3 kj/mol E. 698. kj/mol
10. Which of the following statements regarding molecular solids is/are true? i. All molecular solids have London dispersion forces between the molecules. ii. The melting points of molecular solids depend only on molecular mass. iii. Molecular solids are good conductors of heat and electricity. A. i only B. ii only C. iii only D. i and iii only E. ii and iii only 11. The following is a titration curve for the titration of acetic acid and NaOH. Where is the buffer region? 14 C. 12 ph 10 8 6 A. B. 4 2 0 0 10 20 30 40 50 ml NaOH added A. A B. B C. C D. A and C E. There is no buffer region.
12. A weak acid HA has a dissociation constant K a = 1.0 x 10 7. For a 0.30 M solution of HA in water, which of the following relationships is/are true? A. i only B. ii only i. [A ] << [HA] ii. [H + ] = (K a [HA]) 1/2 iii. [OH ] >> [A ] C. i and ii only D. ii and iii only E. i, ii, and iii 13. A 15.2 mg sample of 90 Sr has an activity of 1.2 10 12 dps. What will the activity of the sample be after 60 years? (The half-life of 90 Sr is 29 years.) A. 1.8 10 11 dps B. 2.9 10 11 dps C. 4.5 10 11 dps D. 6.0 10 11 dps E. 8.0 10 11 dps 14. Magnesium hydroxide is the active ingredient in the liquid antacid called milk of magnesia. The liquid appears milky because of the limited solubility of magnesium hydroxide in an aqueous solution. What is the ph of a saturated solution of Mg(OH) 2 (s) at 25 o C? K sp of Mg(OH) 2 (s) = 5.6 10 12. A. 3.95 B. 10.1 C. 3.65 D. 10.3 E. 7.00
15. Which one of the following is the strongest reducing agent under standard conditions? A. H 2 (g) B. Au(s) C. F 2 (g) D. Li + (aq) E. Na(s) 16. A voltaic cell is constructed: What is E cell at 25 o C when [Cu(NO 3 ) 2 ] = 0.0100 M and [Zn(NO 3 ) 2 ] = 1.90 M? A. 1.03 V B. 1.11 V C. 1.17 V D. 0.969 V E. 1.24 V 17. The addition of which one of the following will result in a decrease in the solubility of CuCO 3 (K sp = 2.3 10 10 )? A. HNO 3 B. Na 2 CO 3 C. NH 3 D. NaNO 3 E. HCl
----------------------------------------------------------------------------------------------------------- 18. Consider the hypothetical reaction that has a positive ΔG rxn. A + 2B 2C + D The mechanism for the reaction is: 2 B k 1 X fast equilibrium k 1 X + A k 2 2 C + D slow Which one of the reaction profiles shown below fits this mechanism? A. B. C. D. E. There is not enough information to choose.
19. Benadryl is an over-the-counter drug that acts as an antihistamine. It is used to treat a number of conditions that include allergies, insomnia, and motion sickness. At 25 o C, an aqueous solution of Benadryl, with a concentration of 0.025 M, has a ph of 10.7. Calculate K b of Benadryl at 25 o C. Structure of benadryl: A. 6.2 10 6 B. 1.0 10 5 C. 5.0 10 4 D. 3.0 10 5 E. 2.5 10 7 O N 20. Consider the following aqueous solution of Benadryl: O N + H 2 O O NH + + OH - Which of the following would cause the equilibrium to shift to the RIGHT at 25 o C? i. Dissolving more Benadryl ii. Addition of HCl iii. iv. A. i only B. ii only C. iii only D. i, ii and iv only E. i, iii and iv only Addition of NaOH Diluting the solution by adding water
21. Nittnium (Nt) cations readily form coordination compounds. Consider the compound: [Nt(en)Cl 2 ]Br 2. What is the charge on the central Nittnium cation and the coordination number of this complex? (en = NH 2 CH 2 CH 2 NH 2 ) Answer Charge on Nt Coordination Number A 2+ 3 B 4+ 3 C 2+ 4 D 4+ 4 E 2+ 6 22. Which of the following structures represents the addition polymer that can be made from the monomer indicated?
23. Which of the following structures represents the monomer that can be used to make the polypeptide polymer indicated? 24. Rick T. Cat needs golden claws for his next great adventure across the deserts of Caldeum and he needs them fast! He decides to use a 60 ampere current to reduce his solution of Au(NO 3 ) 3 into solid gold. How long will it take him to plate 10 grams of gold for his next amazing adventure? A. 148 sec B. 245 sec C. 14,700 sec D. 48,250 sec E. 882,000 sec
25. Consider the following complexes with their respective colors: Complex [CoBr 6 ] 3 [Co(CO) 6 ] 3+ [Co(NH 3 ) 6 ] 3+ [Co(CN) 6 ] 3 Observed Color Green Orange Blue Yellow Based on this information, place the following ligands in order of increasing crystal field splitting strength: Br, CO, NH 3, CN A. Br < CO < NH 3 < CN B. Br < NH 3 < CO < CN C. CO < CN < Br < NH 3 D. CO < CN < NH 3 < Br E. Br < NH 3 < CN < CO 26. Given the following table of thermodynamic data, complete the following sentence. Substance ΔH f (kj/mol) S (J/mol K) TiCl 4 (g) 763.2 354.9 TiCl 4 (l) 804.2 221.9 The vaporization of TiCl 4 is. A. spontaneous at all temperatures B. spontaneous at low temperature and nonspontaneous at high temperature C. non-spontaneous at low temperature and spontaneous at high temperature D. non-spontaneous at all temperatures E. not enough information given to draw a conclusion
27. Which of the following statements are true? i. A chelating ligand will form a more stable complex than a comparable monodentate ligand (assuming the same metal ion is involved) because the entropy associated with chelate formation is more positive. ii. If a solution containing a metal complex is blue, yellow light is being absorbed. iii. A. i only B. ii only C. iii only D. i and ii A low spin complex will have a smaller crystal field splitting (Δ) than a high spin complex if the metal ion and geometry are the same. E. i and iii 28. Which one of the following will have the greatest number of unpaired electrons? A. [Mn(H 2 O) 6 ] 2+ (weak field) B. [Fe(en) 3 ] 3+ (strong field) C. [Ru(NH 3 ) 6 ] 2+ (strong field) D. [Cr(Cl) 6 ] 4 (weak field) E. [Fe(en) 3 ] 2+ (strong field) 29. What would be the observed color of a complex with a crystal field splitting energy of 300 kj/mole? A. Red B. Orange C. Yellow D. Blue E. Violet
30. Which of the following when dissolved in water will form an acidic solution? 1. FeCl 3 2. NH 4 Cl 3. Na 2 CO 3 4. P 4 O 10 A. 1 and 2 B. 1 and 3 C. 2 only D. 2 and 4 E. 1, 2, and 4 31. Which one of the following reactions is BEST described by the graph below: T A. 2 C 8 H 18 (l) + 25 O 2 (g) 16 CO 2 (g) + 18 H 2 O(g) B. Heat + CaCO 3 (s) CaO(s) + CO 2 (g) C. 2 H 2 (g) + O 2 (g) 2 H 2 O(g) D. Heat + 3 O 2 (g) 2 O 3 (g) E. C 6 H 12 O 6 (s) + 6 O 2 (g) 6 CO 2 (g) + 6 H 2 O(g)
32. Chlorine bleach is a water solution of sodium hypochlorite. Regular strength laundry Bleach is typically a 0.70 M NaClO (aq) solution. Given that K a for HClO = 3.0 10 8 at 25 o C, what is the ph of bleach? A. 5.6 B. 7.9 C. 10.7 D. 12.5 E. 13.1 33. 50.0 ml of 0.50 M NaOH is added to a 250 ml solution containing 0.30 M NH 3 and 0.36 M NH 4 Cl. What is the ph of the resulting solution? K b of NH 3 = 1.8 10 5 A. 8.56 B. 9.26 C. 9.08 D. 9.44 E. 12.12 34. One of the ways to determine the concentration of ethanol in the blood is via titration. Ethanol reacts with a solution of dichromate ions under acidic conditions in the following unbalanced reaction: Cr 2 O 7 2 (aq) + CH 3 CH 2 OH (aq) Cr 3+ (aq) + CO 2 (g) When balanced in acid, what is the coefficient in front of H + (aq)? A. 4 B. 8 C. 12 D. 16 E. 28
35. Equal volumes of 0.05 M solutions of several different acids are titrated with 0.1 M NaOH. The acid for which the ph at the equivalence point will be the highest is: A. HClO 4 B. HBrO C. HClO D. HClO 3 E. HIO 36. What is the activation energy for a reaction whose rate constant increases by a factor of 10 upon increasing the reaction temperature from 303 K to 333 K? A. 30 kj/mol B. 33 kj/mol C. 46 kj/mol D. 64 kj/mol E. 89 kj/mol 37. The plot of the experimental data for the following reaction is shown below. 2 A B + C If the slope of the plot is 1.00 M 1 s 1, and the y-intercept is 1.00 M 1 how long does it take for [A] to drop from [A] 0 to 0.50 M? A. 0.50 s B. 1.00 s C. 0.693 s D. 2.00 s E. 100 s 1 [A] t (s)
38. What is the nuclear binding energy of iron-56 in kj/mol? The mass of the iron-56 nucleus is 55.92068 amu. A. 7.90 10 11 kj/mol B. 2.78 10 9 kj/mol C. 4.76 10 10 kj/mol D. 8.78 10 28 kj/mol E. 5.38 10 12 kj/mol 39. Which one of the following statements concerning electrochemistry is FALSE? A. If a voltaic cell has a positive cell potential, it is spontaneous as written and will have a negative ΔG. B. In a voltaic cell when E cell = 0 and ΔG = 0, the system is at equilibrium. C. In order to maintain electrical neutrality in a voltaic cell, anions in a salt bridge flow towards the cathode and cations in a salt bridge flow towards the anode. D. Electrons in a voltaic cell always travel from the anode to the cathode. E. During electrolysis, electrical work pulls electrons from the anode and forces electrons into the cathode to force a non-spontaneous reaction in the forward direction.
40. Using reaction progress kinetic analysis, the following data were collected for a reaction producing nitrous and nitric acid: Using these data, the following mechanism was proposed: NO (g) + NO (g) N 2 O 2 (g) N 2 O 2 (g) + O 2 (g) N 2 O 4 (g) N 2 O 4 (g) + H 2 O (g) HNO 2 (g) + HNO 3 (g) What is the observed rate law consistent with this graph and mechanism? A. k obs [NO] 2 [O 2 ] B. k obs [NO] 2 C. k obs [N 2 O 2 ][O 2 ] D. k obs [N 2 O 4 ][H 2 O] E. k obs [N 2 O 2 ][O 2 ][H 2 O] End of Exam
CHEM 112 Spring 2015 Final Exam - Form A Scrap Paper
1. E 2. E 3. B 4. D 5. A 6. C 7. A 8. B 9. A 10. A 11. A 12. C 13. B 14. D 15. E 16. A 17. B 18. A 19. B 20. D 21. D 22. B 23. E 24. B 25. B 26. C 27. A 28. A 29. C 30. E 31. C 32. C 33. D 34. D 35. E 36. D 37. B 38. C 39. C 40. A Chem 112 Practice Exam 4B Final Exam Answer Key