177Exam3KeyF07

177Exam3KeyF07 - PROF. THOMAS J. GREENBOWE DR. KATHY BURKE...

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Unformatted text preview: PROF. THOMAS J. GREENBOWE DR. KATHY BURKE FALL 2007 CHEM 177 NAME QHSWL’F‘ k8; HOUR EXAM III OCTOBER 22 2007 RECIT. INSTR. THIS EXAM CONSISTS OF 27 QUESTIONS ON 7 PAGES PARTS Page 2 Page 3 Page 4 LRAMNG. POINTS 18 pts 27 pts 21 pts 12 pts 22 pts 100 pts SCORE RECIT. SECT. NOTE: THE METHOD YOU USE IN SOLVING QUESTIONS MUST BE CLEARLY SHOWN IF YOU ARE TO RECEIVE FULL CREDIT. QUESTIONS ARE WRITTEN ON BOTH SIDES OF EACH PAGE. THE LAST PAGE CONTAINS USEFUL INFORMATION AND A PERIODIC TABLE. THIS SHOULD BE REMOVED AND USED FOR ADDITIONAL REFERENCE AND SCRATCH PAPER. DO NOT PUT ANSWERS ON THE TEAR AWAY PAGE. Teaching Assistants and Recitation Sections blame Bernie Anding Cynthia Bunders Shantha Daniel Christopher Ebert Tanya Gupta Emily Hull Zainab Khan Brandon Kobilka Rose Kohl Jason Lupoi Nataliya Markina Emily McDanel Megan Mekoli Derrick Morast Sahana Nagappayya Nicholas Nagle Gerald Pollock Nathan Schulz Justin Valenstein Anthony Young Chad Yuen Sections Time 6, 29 11:00, 3:10 23 8:00 5,27 10:00, 12:10 13, 17 9:00, 12:10 9,11 2:10, 5:10 28, 35 2:10, 5:10 10 4:10 2, 4 9:00, 10:00 20 2:10 8, 15 2:10, 11:00 16 12:10 12 8:00 24, 25 10:00, 11:00 30, 34 4:10, 9:00 18, 22 1:10, 4:10 32, 33 4:10, 5:10 7,21 1:10, 3:10 1 8:00 19,26 1:10, 12:10 3 9:00 14, 31 10:00, 11:00 2 PART I — Multiple Choice. (22 questions at 3 pts each = 66 pts total) 1. To which one of the following reactions occurring at 25 "C does the symbol AHleZSO4(€)] refer? 3) 2H(g) + 3(g) + 40(g) —’ P1250403) b) H2(g) + S(g) + 202(g) _’ 1123040?) C) H2504“) -—> H2(g) + 8(8) + 202(g) d) H2504U3) —’ 2H(g) + 5(5) + 40(g) Hag) + so) + 20g) —> Mom 2. When magnesium metal is burned in a pure carbon dioxide atmosphere (such as dry ice), carbon and magnesium oxide form. The balanced equation is 2Mg(s) + C02(g) —> 2 MgO(s) + C(s) AH? for CO2 (g) is —393.5 kJ/mole AH? for MgO(s) is —601.6 kJ/mole Does AH ° for this reaction indicate it is endothermic or exothermic? rxn a) endothermic exothermic 3. The AE of a system that releases 12.4 J of heat and does 4.2 J of work on the surroundings is J. a) 16.6 b) 12.4 c) 4.2 —16.6 e) —8.2 4. When we watch a fireworks display, the fireworks we see are a result of electrons emitting light energy as they change from a higher to lower energy level. electrons emitting energy as they change from a lower to higher energy level. (:1) none of these. é electrons absorbing light energy as they change from a higher to lower energy level. 5. Of the following, radiation has the longest wavelength and radiation has the greatest energy. gamma ultraviolet visible a) ultraviolet, gamma visible, gamma e b) visible, ultraviolet gamma, visible C) gamma, gamma 6. A possible set of quantum numbers for the last electron added to complete an atom of gallium Ga in its ground state is 3] A 2 n f m m G I0 “‘44 w r’ s r Z I a) 4 0 0 4/2 C-A 1 La (6° (-f .4 ., ,4 b) 3 1 0 4/2 I ’ 2 L 07$ c 4 1 0 +1/2 q / a) @f 1 _1 +1/2 —— — *‘ e 4 2 -1 +1/2 E L n 1L 7L“. ‘1? 10. 11. 12. 13. 14. 15. 3 What is the energy in joules of a mole of photons associated with visible light of wavelength 486.1 nm? 246 k] a) 4.08 x 10'ng b) 6.46 x 10’25 J c) 2.46 x 10—4] d) 12.4kJ Which element has the greatest metallic character (of the ones listed)? @321 The orbital diagram for a ground state carbon atom is a) Ca b) Mg (1) As Is 2s 2p an it LL_..__ b)J‘_L l__l_l_i‘__ on it LLL LL LL LL_ The group of elements that have outer electron configurations ending in ns2 (where n is the row #) are called? a) transition metals b) halogens c) alkali metals alkaline earth metals 6 noble gases Which one of the following is not isoelectronic with Kr? As3+ b) Sez‘ c) Rb+ d) Sr2+ e) Br‘ Which one of those atoms listed below will have the largest radius? a) B Ga c) Br d) Si e) Cl Which element will have the smallest ionization energy? a) Li b) Na c) Be (1) K Rb Which one of the following elements(s) behave chemically similarly to potassium? a) magnesium b) calcium @ lithium Which of the following is an acidic oxide? P4010 d) chlorine e) iron f) beryllium b) MgO c) FezO3 (1) K20 e) Cr203 4 16. Which atom most likely forms an ion with charge of +3? a) 1522522136352 @1s22322p63s23pfi4323d” b) 1322322p‘f’3s‘23p64s1 1522s22p63sl3p64s13dm l7. Metals tend to react with the halogens to form metal halides. What is the reactivity order for the halogens? F2>C12>Br2>12 c) Br2>12>C12>F2 - CIZ>F2>Br2>l2 d)12>Br2>ClZ>F2 18. The four spheres below represent K”, Ca2+, Cl‘, and 8”", not necessarily in that order. 0 A,r=lOOpm B,r=l38pm C,r=180pm D,r=184pm Which sphere most likely represents the K+ ion? a) A B c)AorB d)CorD 19. Sodium is much more apt to exist as a cation than is chlorine. This is because a chlorine has a greater electron affinity than sodium does. c chlorine is bigger than sodium. (1) chlorine has a lower ionization energy than sodium does. e) chlorine is more metallic than sodium. a! chlorine is a gas and sodium is a solid. 20. Which of the following correctly represents the electron affinity of bromine? G) Br(g) + e‘ —=- Br-(g) e) Br+(g) + e‘ —> Br(g) c) Brag) + e‘ -> Br‘(g) aBflg) —> Br*(g) + e’ d) Br2(g) + 2e" —> 2Br‘(g) 21. Alkali metals tend to be more reactive than alkaline earth metals because a) alkali metals have lower densities. b) alkali metals have lower melting points. c alkali metals have greater electron affinities. alkali metals have lower ionization energies. e) alkali metals are not more reactive than alkaline earth metals. 22. For the fourth—shell orbital shown at the right, what are the principal quantum number, n, and the angular momentum quantum number, 1? a)n=4andl=0 @n=4andl=2 b)n=4andl=1 d)n=4andl=3 5 PART II — Problems. Show all work. Answers should include appropriate units and contain the correct number of significant figures. (34 pts total) 23. (6 pts) Ethanol undergoes combustion according to the equation CZHSOHU?) +302(g) —>2_C02(g) SHZOOE) (not balanced) The standard heat of combustion of ethanol, CZHSOHUE), is —1366.8 kJ/mol. Given that AH ?[C02(g)1 = 393.5 lemol T 0 AH $[H20(r) = -285.8 kJ/mol A H «m AH"; CsHiJU ‘- ? What is the standard enthalpy of formation of ethanol? A Him“: 2 A“: Paige—1'5 "‘ ‘2 AH; «Ad-atth —t3u$ . at __ : mo - . mohH ass—Ric.) 1- mac 1 o [ Ink _ Afib [(1 u Coi I flasks“ )+ ( 3 2o ‘ mom ) L l 4S 8103 lQ} flaws: kl '2 [(-WHQH (“257-94 L0] - ['“ACLH5OHAH;] -1356“sz = 4994.4 IcJ — L iszHSOH 5H3] — rum; kJ'HsLHMIg -: ~— that Cassatt AH“; +2??.LkJ—- —lwkcs_asou Arte-9 — laqfié CLl‘lb—OH 3‘ Al? 24. (6 pts) Calculate the enthalpy change for the reac lOIl C(graph) + 2H2(g) + V2 02(g) —> CH30H(€) using the following information: - K “M W (D C(graph) + 049:» Gig) AH; = -3935 k] muhpflzfig Hag) + 1&0“; 2002') AH?=—285.8 kJ mm @ CH3OH(€) + 3/2 02(g) —> CO2(g) + 2 H2002”) AH§=-726.4k.1 G) C(jmpk) +35%) “‘9 E6245] AH} = -593.5 I43 @1 +1105) t J102(5) —-> 2M) A H391: 295.3 lez = $71.1, ® W J“ W) —”C'*30Htm 30— AH°¥3=+71£H a.) ________________._.———___.——-——-— Ik. a AH" :- ‘23%r? (in 6 25. (6 pts) The combustion of pentane (72.17 g/mole) produces heat according to the equation CSHIZU?) + 8 02(g) —> 5 C02(g) + 6 H200?) AH?7m = —3,510 k] How many grams of CO2 (44.01 g/mole) are produced per 2,500 k] of heat released? -1500 5M0i¢COx HH‘tOI C _ “3510 KJ M41. (0; 3C0). 0 r “305031 (2551) 26. (6 pts) Calculate the wavelength (in nanometers) of the light emitted by a hydrogen atom during a transition of its electron from the n = 4 to n = 1 principal energy level. _i_. u. l _ >x ” R“ "v??- w: 'L : LOCI—two} _]___ _ i __W\__ )\ m 1" LP- lxlofiwm "‘ It .0515 .1. 1~ ' 0 : LOT-H10 m A M Mloqwm "LA" -:-. 0.0 [02.8 hmnl l v-O A = "i .- fi¥i otoiol?» nm 27. (10 pts) Complete and balance the following equations. a) C02(s) + H2003) —> HICL)5 (“Lil b) _Ca0(s) + _H20(£) —> Ca (0H); («1) c) Lesa) + LHZOU?) 4’ 2C50HCat) + 113(5) d) kMge) + 7— H20(g) E» M 5mg («1) + H; (3) e) ___Mg0(s)+ __2_..__HCl(aq) —> MSULCQZ) + HLOCQ) °F = 2 (°C) + 32 q = WAT M = (number of moles of solute)! L of solution 1 amu = 1.66054 x 10-24 g qlost + qgained = Avogadro’s Number = 6.022 x 1023 1 hertz = Cyde AB = q + w sec AH:m = EnAH‘Kproducts) w EmAHerac tants) C = 3.00 x 108 3 sec AE'218X10—18J i—i h h _ ' nf ni2 E=h'u=—C or E=hf=—C _ R 1 1 _ R _ 1.097 x 107 h = 6.626 x 10‘3410ule—sec — H 2 — _2 7 H ' — III 112 m )w = c or 78f = 0 Periodic Table of the Elements 1A 1 1 2A 3A 4A 5A 6A 7A 8A 18 2 13 14 15 16 17 He 4.00 5 6 7 8 9 10 BB 8 c N 0 F Ne . . 10.8 12.01 14.00 16.00 18.99 20.2 11 12 38 48 58 68 78 r—‘% 18 28 13 14 15 16 17 18 Na Mg 3 4 5 6 7 8 9 10 11 12 AI 51 P s (:1 Ar 23.0 24.3 27.0 : 31.0 32.1 35.5 39-9 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni CU Zn Ga Ge As Se Br Kr 39.1 40.1 45.0 47.9 50.9 52.0 54.9 55.84 58.9 58.7 63.5 65.4 69.7 725 74.9 79.0 79.9 83.8 37 38 39 40 41 42 43 44 4s 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te | Xe 85.5 87.6 88.9 91.2 92.9 95.9 (98) 101 103 105 108 112 115 119 122 128 127 131 55 56 57 72 73 75 76 77 78 79 80 81 82 83 84 5 86 74 8 W e 5 r o A n 133 137 139 178 181 184 186 190 192 195 197 201 204 207 209 (209) (210)(222) 104 105 106 107 108 109 110 (223) 226 227 (261) (262) (263) (262) (265) 58 59 60 61 62 63 64 65 65 67 68 69 70 71 Lanthanides Ce Pl" Nd Pm Sm EU Gd Tb Dy HO Er Tm Yb LU 140 141 144 (145) 150 152 157 159 162 165 167 169 173 175 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Acfinwes Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 232 231 238 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) (266) (281) ...
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This note was uploaded on 03/26/2008 for the course CHEM 177 taught by Professor Greenbowe during the Fall '06 term at Iowa State.

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177Exam3KeyF07 - PROF. THOMAS J. GREENBOWE DR. KATHY BURKE...

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