CHEN1211Spring08Test2

CHEN1211Spring08Test2 - Aasmae (<91! CHEN 1211...

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Unformatted text preview: Aasmae (<91! CHEN 1211 Midterm Exam 2 Wednesday March 19, 2008 Instructor: Prof. Doug Gin This is a closed book exam. There should be a total of 11 pages to this exam booklet including the cover page, a list of constants and conversion factors / salt solubility table, 2 equations pages, a table of bond dissociation energies, and a copy of the Periodic Table. There are 17 questions in this exam worth a total of 100 pts. There are five 8 pt questions and twelve 5 pt questions. Answer all questions on the separate Scantron answer sheet by darkening in the proper bubble with a number 2 pencil. If you change your answer, be sure to thoroughly erase the undesired mark. Make sure to write and bubble in your name and SID number on your Scantron answer sheet. Read the questions carefully. Note the point value of each question and budget your time accordingly. Feel free to use the front and back of your exam booklet pages for scratch paper. The exam booklet is not to be handed in. Any answers not included on the Scantron answer sheet will not be counted. You have a maximum of 1.5 hours to complete this exam (7:30 —9:00 PM) GOOD LUCK! By taking this exam, you agree to abide by the CU Boulder Honor Code for this test, as stated below: Honor Code Agreement: "On my honor as a University of Colorado at Boulder student, I have neither received nor given unauthorized assistance on this work." Additional restrictions: (1) Please turn off all cellular phones and other related wireless communication devices. The use of such communication devices is prohibited during the exam. (2) Calculators are allowed in this exam, but devices capable of storing more information, such as PDA’s, laptop computers, etc., are not permitted. (3) The use of headphone audio devices capable of data storage such as MP3, CD, and cassette players are also not permitted during the exam. Any student found using such restricted devices during the exam will considered to be cheating and will be reported to the CU Boulder Honor Code Council for punitive action, as outlined in the class policies. ‘ (1) Which of the following pairs of elements homogeneously combined in a 1:1 (mol/mol) mixture would be the easiest to separate by giggion throu h a porous membrane at standard conditions? (5 pts) 5.5;? mg: ___.1. g l Fla»I mm a a “mks-rm HOL . . C, C09 but“ F‘ l = mete-r59” run, (a) 1W zen-u emiss- @(95 Ha o< ;( Fag (b) fluorine and xenon F; 92, Xe g anpkasm,“ 0 hydrogen and helium H, 32‘ w; :7 ~ magma. (“gut—st helium and oxygen H: _\J_$~_ 0;. :7 pk rams Big-(E: e) fluorine and oxygen F3 ‘5‘ o 55> on Mug mow Mensa e (2) What is the formal on the S atom in the SO42- molecular ion? (5 pts) ( QM mum-1*) 13: \L a.“ a ) _ b —1 ‘dze <5? 0 u C»: H 9 +1 —-'O.‘ > (e) +2 @\ C'lk “ Too HUGH . , , Au— mm we. oom- . Fae MUCHPLE saws. (3) Ketene IS an organic molecule With the structural formula: HZCCO. What IS the valence "9 orbital hybridization on the C atom bonded between 0 and the first C atom, and what is the overall shape of this molecule based on the arrangement of the CC0 backbone? (5 pts) , U. e...— z: 3 + a. Y + = ( ED -‘ $511353: it am ((7; (SB «5%) e (c) sp3: bent (d) sp3d, trigonal bipyramidal (e) sp3d2, linear ‘ W H k 5? wamblm; 36’ Bank} [80" APNzr cm ants CAI-aw (4) The number of energetically equivalent resonance structures for N03" is: (5 pts) at» def": 5+- :aé») + l e» 34:,” (a) 0 we _ 01‘» (3'0 cw!) (b) 1 :0 e '0. _. he 7:6. “6‘3 0 2 '.\ N45. 9 FREQ/A; @ 3 51mm ‘fi 3 l \ has (5) The molecular shape @C13 is: (8 pts) , _ _ i _. chznma MM 1t? U‘e‘ " 3 " s‘ft (a) square pyramidal . a (b) trigonal bipyramidal :d g g paemNg (d) octahedral a ( a H a a" 0Fci’ bBN‘JTV see-saw , "wk __N o __... l I _ M2130»; mm” e square planar ° 9 l. 9.“ \"‘-—~.;~;» ' I 41.“- “ "a" a?“ BuT’ Lowe: ma @. EQUAT‘ORAALM Postman Mb mammal) IN HDL.‘ Sit-NEE; awn (6) (7) (8) A": D‘s'm’m‘ Which of the following molecules has the smallest bond angle? (5 pts) ; If; as ve.’ (a) BC13 ~7me. PM namwe. (EXQO, (b) C02 - mum 123° @1 s) a H S I N I 1” l30 (c) 2 v \j- w'fibeHk-E $50)) lO‘i : : ‘gd £3152 ' “‘“m) we" ‘ “‘ r3 - -r— fi0° bank/mews L 1. " P: UV w— 4% Which of the following i35fécules would you expect to “have a permanent molecular dipole moment? (5 pts) (3) CH4 __ TA swing, w nun-Pout + 9M C32 3:39:33: me+ 9011 “Al-b binge—s CANCEL OCS {CS—EC as} me Bun" gsvm 5) gas biPoLE; is A an- BF3 —- mté m Hana 917%‘5553? W 195 (e) XBF2.-- LtNEM»&*-“$‘~(H~ mePocM: “ME ‘3 “warms The balanced reaction below has been studied in the laboratory, and the following initial rate data were obtained: m =. Jamming” (N $545M— 2A+B+C—>3D+E+F LAJQ (mol L41 L111!) (mol L—lz [Q9 (mol L—ll Initial rate 1—dIBI / dtl {mol L”1 8—1! on ma: .9, . ME (H 0.100 0.100 0.100 5310);]K a 13% WSW 0.20035 xa 0.100 0.100 1 KM so 0.300 0.100 0.100 x 1500 0.100 0.2 0.100 K 2000 g, 0.100 0.300 0.100 4500 :53 Wald: 0.100 0.100 0.200 X3 1000 mm 0.100 0.100 0.300 1500 ED] (Na: aw. @HE..F,~mQ} 9° [ZmE (M5 3% Hana? _" ’ What is the overall rate law for this reaction, and the value of the rate constant (k)! (! pts) Rate = k [A] [B]2 [C]; k = 5.00 x 106 L3 mol-3 s—l . Rate = k [A]2 [B] [C]; k = 5.00 x 104 L2 mol2 3‘1 (c) Rate = k [A] [B]2 [C]2; k = 5.00 x 105 L2 mol2 3‘1 (d) Rate = k [A]2 [B]2 [C]2; k = 5.00 X 107 L mol'1 8—1 (e) Rate = k [A] [B]2 [C]; 51k = 5.00 x 103 L mol-1 s—1 : $1-12 50a: ,1 s a. =_ COJ‘OOM(OJOGML'O (O‘IQQM'L'O ":— 5’.oo XIOéM'3L35-( 3 (9) Phosgene gas was used as a chemical warfare agent in World War I. If a sample of phosgene gas weighing 0.152 g has a volume of 48.3 mL at 100.0 °C and 740 mm Hg pressure, what is the molecular weight of phosgene, assuming that it behaves as an idea] 9 , gas. (5 PtS) 3 n M: H‘w‘ 5 a M ’m (a) 14.1 g/mol : - at E a > (b) 2.02 g/mol : . PM = @3121" M f\ C‘Hm (c) 18.0 g/mol 4'; 0.658302, 373.19 K 0‘ 127.3 g/mol .‘, MW 5’ mg?!" = o$wflc I ~ 6 4 l__~ (é) 98.9 g/mol (LWWMHS - .0 83 I: a M 14.4 (10) Estimate the AHf;n for the following reaction using the Table of Average Bond Dissociation Energies (D) at the back of the exam. (8 pts) H H O \ / / \ [0: C\ + H—O—O—H ————> HJ‘: C—C< H + H20 H—/C\ H H/(i H H ‘ ° ' H H H BONb§ fl ' aauga EOE-"EA _259 kJ * WWW MN I (b) —100 kJ ‘ KC‘Q 35‘3"“ (0) +52 kJ M, M (d) +130kJ I a“? a “ 9 era 9(350 4T) (e) —150 kJ “aware”? M o~o 12012: I , , AHM’ECZ hm» ~Zl>gg§g§ = (ét(+(<zo)v(3xaso)= (11) What external pressure would required to make ater boil at room temperature (25 °C), if the normal boiling point of water is 100 °C and its AHgfip is 40.67 kJ/mol? 35 pts) (3) 788 mm Hg (én F> “A” F; 3 +- (b) 760 mm Hg . L A.“ ‘ @252) ((0.013) ~ w»»-£—arr—.v+r-,>J w @ 28.1mmH‘g’3‘aq8’ :QW "meatlgj {:38 g. oégfizm ,M => — 3.9%? (12) Which of the following c micafihermodynamics is NOT true. (5 pts) . O \ The entropy of an element in its standard state at 25 °C and 1 atm is zero. 3 a: O Q o ‘S . An exothermic reaction always releases heat. 4; =6 FOR. (c) A reaction that is spontaneous as written can have a AS that is negative. m (d) A reaction that is spontaneous as written can have a AH that is positive. M (e) The internal energy of a system takes into account heat transferred and the work done. ' (13) For which of the following chemical processes would you expect AS° to be negative. (5 pts). (a) CH4(g) + 202 (g) —> C02(g) + 2H20 (g) (b) NH3 (1) —> NH3 (g) N2 (g)+2H2 (g) ~——> N2H4 (g) 2) Bmé ms. -=> (wagging; ) 2H20(I) ——> 2H2(g) + 02 (g) WZQMM m 5%; (e) CH4 (g) + C12 (g) —-—-> CH3Cl (g) + HCl (g) \himwmmwmw FLlP In GET H911) A6 ’(TZ'T IfAHfWfiE'H(g) + mg) J AHvap for HF (I) using th1s1 o" ' . ' my “flaw—m... , is found to be -564.2 k], det rrnine the V owhrgenthalpy‘data‘. pts (a) 11.3kJ _ " ' (c) 5:5?) T? (a » (58.; l (e) 8.1kJ +1: F" _,__: 519'? M..- k — ((4; (AT) x A ... Warm-..“ ° ~ "' 55’ . g Mm“- . My. (15) At —189 °C, argon reezes to form a crys me so 1 w1th ace—centered cubic latti . The shortest distance between the centers of two adjacent argon atoms is 0.382 nm. What is t # ATOME density of solid argon at this temperature? (5 pts) 1“, a H 5 to F6 C ( 0425 /c 3 “‘33 “MT “Wm me A. K H wer a . m r g - v 8 g (6’ 1.6a‘g/cm3 / :v x 3‘1. 4 v c) 1.19 g/cm: 1,..3110” E M (d) 4.79 g/cm : 09} ’33 (e) W‘Q.é/&/m3 255m Q.é53 No I "a; bLS’MME» m BAfiT )AV‘A'mug = 84‘ -: 0.3?9/Nm wwwxmmwmmy. k—nowmc; W on bombard“. ’ — . (16) The industrial synthesis of ammonia gas uses the Haber process as shown below: + ———* 2:; : 53-925; This reaction is reversible. Assuming that AH and AS do not change much with temperature, at which of the following five temperatures listed below is the Haber process spontaneous for formation of ammonia gas? (5 pts) 03 . E a z 9 = 100°C @ QDWFT’. AG 0 _ , AH 722% . 200°C ~ __ A (c) 300 °c FM. MEé.AH m G ‘ '1" a, 4% (d) 400°C 'TEZ-H TD bot-(INA tr _¢?a.;’m—— (e) 500°C 6!: AC7 -_~. AH'TAE‘: m 6}) “we? , K Tfiug' BE Loam WM wins —— v 465.3 :1 0° . Wu”? (17) The reaction of 1 mole of N2 (g) with 3 moles of H2 (9 to form NH3 (g) releases 92.2 k] of heat, as described in Question 16 above. This reaction is run to completion in a sealed bomb calorimeter initially containing 0.250 moles of N2 (g) and 0.750 moles the end of the reaction, the temperature of the entire system was found to 235 ° If the heat capacity of the calorimeter is 82.8 J/°C, what is the molar he acity of NH3(g)? (8 pts) (a) 29.1 J/(mol - °C) . __... (b) 24.4J/(mol-°C) “’ + 3% mp QNL’E, AH = dug/Er 50.5 J/(mol - °C) Para. mt,” an“ NA 05% (a) 30.6 J/(mol-°C) e) 61.2 J/(mol-°C) m 0.35?) mi N; ' GP'RAT __ .... 33 og 1645' legiogéé 3 m " tweets» sea We l5 mum-r M’Lasmb m awest-sme, = WT” Afimw + W 3% =~ (CPR) +>Q1MVQC2~J I = 0,503MMB ...
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CHEN1211Spring08Test2 - Aasmae (&amp;lt;91! CHEN 1211...

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