CHEM2A FINAL Fall2008 KEY

CHEM2A FINAL Fall2008 KEY - First Name: Lab day/time: Last...

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Unformatted text preview: First Name: Lab day/time: Last Name: Lab Sec. # TA: Andreas Toupadakis, Ph.D. CHEMISTRY 2A Final Exam - Fall 2008 Instruc fians: CLOSED BOOK EXAM! DO NOT OPEN the exam until instructed to do so. No books, notes, or additional scrap paper are permitted. All information required is contained on the exam. Place all work in the space provided. If you require additional space, use the back of the exam. A Scientific calculator may be used (if it is a programmable calculator, its memory must be cleared before the exam). Sharing of calculators is not allowed. (1) (2) (3) (4) (5) Read each question carefully (28 problems, 15 pages). ANSWER ALL THE QUESTIONS YOU ARE SURE OF FIRST, AND THEN USE THE REMAINING TIME FOR THE REST. Please show all relevant work where it is indicated for full credit. The last 2 pages contain a periodic table and some useful information. You may remove them for easy access and for scratch. If you finish early, RECHECK YOUR ANSWERS! U.C. Davis is an Honor Institution Possible Points ‘1 Points #1—13 (3 points each) ‘ / 39 # 14-19 (5 points each) ‘ / 3O # 20-21 (48 points) ‘ / 48 # 22 (10 points) / 10 # 23 (10 points) / 10 r11¢ 24-25 (16 points) / 16 # 26 (30 points) / 3O # 27 (06 points) ‘ / O6 # 28 (08 points) l / 08 Total Score (197) l / 197 Multiple Choice 5 bcde 6. ab©de 7. abcd@ 8. [email protected] 9. [email protected] 1o.@b c d e 11.0 b [email protected] [email protected] 13.abcd@ Circle one FALL 2008 FINAL CHEM 2A (Page 2 of 15) Concepts: Multiple Choice Questions 1—13: 3 points each (no partial credit) 1. A balloon is filled and sealed with air at sea level. If the balloon is taken to a city at 12,000 ft above sea level, what could be the result? a A decrease in volume of the balloon c. An increase in pressure of the balloon d. A decrease in the number of moles of air in the balloon e. An increase in the number of moles of air in the balloon 2. Choose the correct electronic configuration of A9? a. [Kr]4d9 55‘2 b. is2 252 2p" 352 3p"4s2 3d1° 4p" 552 4d1° c. ls2 252 2p6 3s2 3p6 452 3d10 4p6 552 4d10 5p4 d- W] - , 3. Which bond from below is most ionic in character? b. LiCl c. LiBr d. LiI e. LiAt 4. Choose the INCORRECT formula-name combination. a. FeClz ferrous chloride b. FeC|3 ferric chloride genwtrio ide 2 3 e. K3N potassium nitride 5. Choose the net ionic chemical equation that corresponds to the resulting reaction by mixing an aqueous solution of ferric chloride and an aqueous solution of potassium sulfide. by. c. 2 Fe3‘(aq) + 3 5032'(aq) 9 Fez(503)3(5) d. Fe2*(aq) + SO42’(aq) 9 FeSO4(s) e. no reaction FALL 2008 FINAL CHEM 2A (Page 3 of 15) 6. Which of the following combinations could give the quantum numbers (n, l, m, m) for the single valence electron of the copper atom in its ground state? a. 4, O, O, 3/2 G b. c. d. , 8. Which of the molecules listed below has the smallest dipole moment? Cl. b. CO C. Q4. 9. Which of the following is TRUE about first ionization energies? a. Na<Mg<Al b. Si<P<S c- __,,N_9 > i > 6' None of the above S“ 1.9: 10. The central atom of a molecule has three lone pairs and is bonded to each of two other atoms with a single bond. What is the molecular geometry (shape) of the molecule? b) Trigonal planar c) Trigonal bipyramidal d) Octahedral e) Square Planar FALL 2008 FINAL CHEM 2A (Page 4 of 15) 11. How many 0 bonds and how many TI bonds are present in the HCN molecule? a. 10/11T b. 10/211 c. 30/211 e. O o /O 11 12. If you aswme 5p3 hybridization for a free nitrogen atom, how many lone pairs of electrons will the free (not bonded to other atoms) nitrogen atom have? _ 0 599—9979 1 2 3 4 13. Gases are described by which of the following characteristics? a) Indefinite shape and volume b) Able to expand and compress c) Relatively low densities d) Able to diffuse to form homogeneous mixtures FALL 2008 FINAL CHEM 2A (Page 5 of 15) Calculations: Multiple Choice Questions 14-19: 5 points each (no partial credit) 14. A gas is collected and found to fill a volume of 2.85 L at 250°C. What will be its volume at standard temperature? 15. Iron ores contain iron oxide minerals, which often contain ferric and ferrous ions. Such an ore can be analyzed for its iron content by dissolving it in acidic solution, reducing all the iron to ferrous ions, and then titrating with a standard solution of potassium permanganate. In the resulting solution, permanganate ion is reduced to manganese (II) ion, and ferrous ion is oxidized to ferric ion. A sample of iron ore weighed 0.3500 g. The titration required 41.56 mL of the permanganate solution (1.621 x 10‘2 M) to reach the light purple end point. Determine the mass percent of iron in the iron ore. b. c. 33.75% d. 23.75% e. 13.75% FALL 2008 FINAL CHEM 2A (Page 6 of 15) 16. In the past, acetylene Csz was produced by reacting calcium carbide with water according to the following chemical equation: CGCz + 2 H20 ‘9 CO(OH)2 + Csz What would be the volume of acetylene gas produced at 25°C and 0.950 atm by the reaction of 128 g of calcium carbide and 45.0 g of water? a. 45.2 L 17. Equal volumes of a 6.0 M KN03 solution and 2.6 M NaCl solution are mixed. What is the molarity of the new solution in KN03 and NaCl? a. 6.0 M KN03 and 2.6 M NaCl b. 2.6 M KN03 and 6.0 M NaCl c. 12 0 M KN03 and 5 2 M NaCl e. none of the above FALL 2008 18. 19. FINAL CHEM 2A (Page 7 of 15) To whaT uncertain’ry (in m) can The posifion of a baseball Traveling of 45.0 m/s be measured if The uncertainty of HS speed is 0.10%? The mass of a baseball is abouT 0.145 kg. r- 10.33,; m b. 5.6 X 10'15 m c. 6.7 x 10'45 m d. 5.9 x 10'14 m e. 4.4 x 10'65 m Au"; *‘(02’10/1oofifi45 " How many grams is a wafer molecule? a. 2x10239 b. 3x1023g S“ .0- FALL 2008 FINAL CHEM 2A (Page 8 of 15) 20. (6 poinTs) Fill in The blanks wiTh The correcT ground sTaTe elecTron configuration (noble gas configuraTion) for The given aTom or The aTom for The given ground [Ar] 3d10 452 l 21. (42 poinTs) Fill in The following Table (see The C/F3 example). For The deTerminaTion of formal charge(s) consider The Lewis formula wiTh The smallesT formal charges (lowesT energy). sTaTe elecTron configuraTion. ATom l ElecTron ConfiguraTifl EIecTron- H brid_ Formal OxidaTion Group Ideal Polar or .y . Charge(s) Number Molecular IzaTIon Molecule GeomeTry Bond Nonpolar of The of The GeomeTry (cenTral (cenTral Angles Molecule Mom) underlined underlined aTom) _4 elemenT elemerii cu:3 Tr’gm‘ll' T-shape 9011809 polar 5de 0 -1 Blpyram/da/ '— EEClz 592 Tr"91‘%"L‘“ Planar? ‘ BFa J Biff, §F4 FALL 2008 FINAL CHEM 2A (Page 9 of 15) Partial Credit. Show 5],]: Your Work. Explain. 22. (10 poin‘rs) Into a 5.00 L com‘ainer‘ at 18°C are placed 0.200 mol H2, 20.0 g 602, and 14.00 g 02. Calculate The To’ral pressure in The container and The par'Tial pressure of each gas. P(COz) [(0: n(Q:*)if=,“(14590:,9571 FALL 2008 FINAL CHEM 2A (Page 10 of 15) 23. (10 poinTs) Draw The Lewis elecTron doT diagrams for The following chemical species and include all reasonable resonance diagrams, if any. HinT: Minimize formal charge wiThouT breaking The OcTeT rule unless The aTom is in period 3 or higher. A. PO43' (phosphaTe ion) B. 62042' (oxalaTe ion) C. CHsNHz (meThylamine) F I:9:I i 1:2: FALL 2008 FINAL CHEM 2A (Page 11 of 15) 24. (12 poinTs) A 5.00 9 sample of a gas mixTure, consisTing of meThane, CH4, and eThylene, CZH4, was burned in excess oxygen, yielding 14.5 g of C02 and some amounT of waTer as producTs. WhaT mass percenT of The sample was eThylene? HINT: WriTe and balance The chemical equaTion for each reacTion Taking place before you sTarT working on The problem. ‘74 Ii<2:o,2;:g 25. (4 poinTs) Consider The polar chemical species XeOZCIZZ'. A) Draw The Lewis elecTron doT diagram. B) Draw a diagram, show and sTaTe The geomeTry around The cenTral aTom. FALL 2008 FINAL CHEM 2A (Page 12 of 15) 26. (30 poinTs) CompleTe The MO energy level diagram for 022‘. a. Fill in The elecTrons using arrows (T and/or l) for The aTomic and molecular orbiTals. b. DesignaTe a_H The energy levels (i.e., 025*, 112p, 025, eTc.) c. CalculaTe The bond order for 022'. d. Is 022‘ a paramagneTic or diamagneTic chemical species? a. and b. c' Bond order for 022' = 1 ParamagneTic or DiamagneTic? FALL 2008 FINAL CHEM 2A (Page 13 of 15) 27. (6 poinTs) WriTe ouT The four possible quanTum numbers for each of The elecTrons in The diagram below. Give Them in The order of: n, l, m, and ms. HINT: There are 6 elecTrons Therefore you should give 6 answers. I 2;) 1s 2s Zp'elecTrbns 28. (8 poinTs) Consider The reacTion represenTed by The following chemical equaTion: Crzoyzxaq) + CszOHU) e Cr3*(aq) + 602(9) EIemenT being oxidized: EIemenT being reduced: b. WriTe and balance The oxidaTion half reacTion in acidic soluTion. Czl’leO‘T3E4‘:Héf‘yg c. WriTe and balance The reducTion half reacTion in acidic soluTion. d. WriTe The overall balanced redox chemical equaTion in BASIC soluTion. FALL 2008 Solubility rules: FINAL CHEM 2A Compounds which are soluble or most/y so/ub/e: Group 1, NHJ, chlorates, acetates, nitrates Halides (except sz’, Ag*, and ngz‘) Sulfates (except Sr”, Ba”, Pb”, and Hg”) Compounds which are Ihso/ub/e: (Page 14 of 15) Hydroxides, sulfides (except above rule, and sulfides of group 2) Carbonates, phosphates, chromates (except above rules) Some useful equations and data: PLEASE NOTE: Important values and equations required for calculations are given with the respective problem. The following may or may not be of any use. NA = 6.022 x1023 h = 6.626x10‘34 Js 1J : 1kg m2 5-2 = 1 N m photon A Z i. d : P_M mu RT PV = nRT mL-M = mmol PM” = P1 + P2 + 1nm:10‘9m c: 3.00x108ms'1 E : hv latm = 760 mmHg Ratez/Ratel‘-‘(M1/M2)1/2 e = 9.109387x1o-28 9 _l_—_——"_—l_——__———— Moles Molari = ty Liter TK : Toc‘l' c=v/l lg = 6.02x1023 amu 11 (moles) = R = 0.0821 L atm mol'1 K-1 ‘l————f~—————— XA : nA / "m = PA / Pm AE = RH(1/ni2- 1/nf2) mass (g) molar mass (g/mol) i———i ApzmAU % Yield 2 Theoretica 1 Yield _V m _.___ Actual Yield x100 FALL 2008 FINAL CHEM 2A (Page 15 of 15) Potentially Useful Information (You may remove This page for ease of access) Key 1 Atomic Number 2 H Symbol He 1008 Atomic Moss EIecTronega’rivify _ 5 6 7 8 9 10 B C N O F Ne 10.81 12.01 14.01 16,00 19.00 20.18 2.04 2.55 3.04 3.44 3.98 - 13 18 Al 5i P 5 Cl Ar 26.98 28.09 30.97 32.06 35.45 39.95 1.61 1.90 2.19 2,58 3.16 - 24 25 26 27 28 29 30 31 32 33 34 35 36 Cr Mn Fe Co Ni Cu Zn Ga Ge As 5e Br Kr 52.00 54.94 55.85 58.93 58.70 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80 1.66 1.55 1.83 1.88 1.91 1.90 1.65 1.81 2.01 2.18 2.55 2.96 - 42 43 44 45 46 47 48 49 5O 51 52 53 54 Mo Tc Ru Rh Pd Ag Cd In 5n Sb Te I Xe 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 2.16 1.9 2.2 2.28 2,20 1.93 1.69 1.78 1.96 2.05 2.1 2.66 - 74 75 76 77 78 79 8O 81 82 83 84 85 86 W Re Os Ir PT Au Hg Tl Pb Bi Po AT Rn 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222) 2.36 1.9 2.2 2.20 2.28 2.54 2.00 2.04 2.33 2.02 2.0 2.2 - 106 107 109 Unh Uns Une 57 58 5 60 61 62 63 64 65 66 67 68 69 70 La Ce P Nd Pm 5m Eu Gd Tb Dy Ho Er Tm Yb ' I 2 ~ 1 2 23 V 50.94 1.63 39.10 40.08 1.00 21 Sc 44.96 1.36 Y 88.91 1.22 Lu 175.0 127 103 Lr‘ (260) 5r 87.62 0.82 0.95 55 56 Cs Ba 104 105 Unq Unp 9 I" 1389 1401 1409 144.2 (145) 150.4 152.0 1573 158.9 16215 164.9 167.3 168.9 173.0 1.10 1.12 1.13 1.14 1.13 1,17 1. 1.20 1.22 1.23 1.24 1.25 1.1 89 9o 91 92 93 94 95 96 97 98 99 100 101 102 Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No (227) 232.0 (231) 238.0 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) 1.1 1.3 1.5 1.38 1,36 1.28 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 ...
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This note was uploaded on 10/22/2010 for the course CHE 2A CHE 2A taught by Professor Enderle during the Fall '09 term at UC Davis.

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CHEM2A FINAL Fall2008 KEY - First Name: Lab day/time: Last...

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