Midterm 3 Key - Chemistry 1A, Feii 2006 Midterm 3, Version...

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Unformatted text preview: Chemistry 1A, Feii 2006 Midterm 3, Version A Nov 14, 2006 {9ft min, eioseti hook-J Name: SID: 651 Name: I There are 24 Muttipie ehoiee questions worth 3.?5 points eaeh. I There are 5 short answer questions. i For the muitiple ehoiee section, fill in the Seantrou form AND eirele your answer on the exam. - Put your Iinal answers in the boxes provided. Answers outside the hoses may not he eonsidered in grading. - The homework and eltemquiazes that each question is based upon is listed after the question e.g. {11W 1.13. CQ 13] I Question 23 5.} Question 29 ID Totai Page 1 NOTE! 1' riff ther'mtnrfltnmnfe Forfoht'es reIEr to the system mn’ess otherwise stated. 3) The .rymhm’ "H " a'a'h' be used to denote potential} eqm‘h‘hrmm reactions. For questions i — a consider the following three step process shots-r: on the P‘s” diagram for one mole ofari idea] gas initiatly at 1 atm pressure and EEK. Step 1: The gas expands isoU-termalh; from 22.4 L to 44.8 L {point I to 2 on the Pie" diagram}. Step II: The gas is cooled and compressed baeit to its original volume {point “I to 3 on the PU diagram]. Step III: The gas is manned haeh to its original pressure and 1mlorrte {point 3 to point I on the P‘s-F diagram}. I.) ‘i‘u’hieh is true ofthe gas for step1?[[‘.Q 23.1] s) at :-~ 1'} a} at = o e) at" e a o) q = a . F.) none ot'lhese 2.} ‘t‘n’hat is the temperature [K]: of the gas at point 3'? a.) HE E} 425 C} ass or; 13? E} 5? 3.} Which is true oi'the gas For step I'? ECQ 23.1] A} Work is done on the gas with no heat transfer. Bi The gas does 1work with no heat trans t'er. C] The gas does work and absorbs heat. DJ Work is done or: the gas and it releases heat. E} Cajmot be determined. Page 2 4.} Which is true eithe gas Fer step iI':J [HW 6.5] A} Wertt is dent: en the gas with no heat trans Fer. 13} The gas {i035 wnrk with an heat transfer. C] The gas dees werit and ahserhs heat. D} Work is done on the gas and it reieases heat. E} Cannet be determined. 5.} 1tin-"l'tieh is true et'the gas t'er step III':1 [HW 15.] t] A“: Heat is ahset‘hed and ne work is dene. 3] Heat is reIeased and ne wart; is dene. C} Heat is absorbed and were is dene en the gas. D} Heat is ahserbed and the gas dees werit. E} Cunnut be determined. it.) 1|t-‘Ir’hich is the cerreet arrangement DFLhe three paints ti, 2, 3} in the PU diagram frera highest to Iewest internal energyr E? [CQ 23.] HW 6.5] A} sass] m 3=2at e; tasal a; 1a2=3 Page 3 For queattona 'F — it‘i consider the following table of data for reactions among two unknown diatomic molecules X: and Y1. Ran Reaction K. {equtlthrtum} Temp ' Number {K} 2 KY tg} H x2 tuf_}_+ Y: t& .:e_o H 2 x to 'F.) Which reactionta} in the tabie are spontaneous at tUDUK starting, from the standard State? [CQ 31.1HW 9.15. 9.1131] A} 1 a) II C] III D} All three E} None 3.} 1Which is one of at!“ For reaction II? A) an” 3’ If} B} aH“ = {J C] an“ e o D] Cannot be determined from the infon-nation given. 9.} 1titthici't is true oFoS” for reaction 11‘:1 [LPN 1.25)] A} as.“ :-~ o B) 515“ = D C} ate '1 Ct D} Cannot be determined from the information given. 1G,} What is the 1wattle ofaCr'” {Id} for reaction II] at IDUUK? [i-IW 9.15] It} 33 a} —45 t“) 22 E} —‘.|1 1.} 1iii-J'tticlt is true of reaction I? n} are :=- n B} are = t} c; an” e o D} Cannot be determined front the information given. Page 4 12.] Which is the beet pint nifitfi” vs. T fer reactions II and III trenrtien 11 is the scaliti line. reaction [11 is the t10ttec111ne}?[£‘Q31.2_ I9.1611 13.1 What is the value an [the equilibrium constant} at 1111111K for the reactinn: W Le} -~ K (g1+ ‘r {g}? [Hw 5.25 A1 4.1511115 [1} 5.5 .v. m"- C] it: x 111* D) 1.2 x ttr'” E} 2.5 x 15* 14.1 1Iii‘vililieit is true For reactit‘m II at 1111111114: when 1 mm X; and 1 atm X. are present?l JH‘W 1“1.17". 130 31.1} A] K = 1 B] 5.0“ = U D} Q '— K 131 Q < K 15.1 For which partial pressure nth: utnmt-r 15 fit“: '—' 11m 11111111151 for reaction 11 when 1.1111 atm 5th is present [11W 9.11]? ft} 1.01:1 atnt 13.} 3111.1 atnt {7'} 1.13: 10" mm D} 3.2 it 111" atm E) 3.4 x 11'1"J atm Itin Which is true For the relative bend enthalpies III—X and 11-1”? EHW 9.39] A} Xv}: it V—‘i’ E) X-X = Y-‘I’ C1 Ks}: 5’- Y-‘t’ D1 Cannot be determined From the mint-[nation given. Page 5 Consider two compounds in their gas phase: ethanol {CH3CHIDH} and ditnethyl ether {CHEDCIIJ} and their combustion in oxygen to form carbon dioxide and liquid water for questions 17" a 27". Unless instructed otherwise, you should use standard enthalpies and Ilcss’s Law to calculate enthalpies of reaction. Compound— Abbreviation oil-Ti: (formation) all:t {combustifi I 1 _ [kl-"molt {kl-"HIGH ' ethanol {g} : EtDl-l . 912731 {CllJCHJUH} I L dimethyl ether {g} DiMe ' I 4328 EHaflCHE) carbon dioxide tg} -394 {C02} I I. water {111F110} '235 fl __— l'i'.} 1l.ir'hat is the eoefficient of D; in the balanced chemical reaction for the combustion ofone {I 1 mole ofdirnethyl ether? Al 1 B} 2 C} 3 D] 4 E} 5 13.} llonr much heat {kl} is released when it] g ofethanol is reacted with excess oxygen [aw ear]? A] 12H a} 1332 C) L492 D} 1555 E} 1645 19.} Which ofthe following is responsible for the sign eras“:- {the enthalpy of combustion} for ethanol? A} Breaking C—l—l and Cat: bonds. B] Breaking CI—H bonds. C} Forming C—H bonds and DC bonds. D} Forming Chi: and 0—H bonds. E} Condensation of the water formed. 213.} 1ir‘tl'hieh statementts} {I W} below are true regarding at i". for the gas phase isonierization shown [HW 6.56:. am}? CH3CH10H —. CtlgflCl-lg 1 any: ol-I‘utCUg} — oI-l";{EtClll} {1 ant: oli=dDiMejt — ante-non}. Ill any: anacon - aH’frHZo} w an: = an‘rrsiom ‘ flH°cmiMej A} I only 13] I and ll C) ll only D) it and W E} III only Page 6 21.} 1t't’hat is art: {kl} for the gas phase isornerizatioo reaction shown? [HW anl - oozes] CHJCHgDH {g} —> tit-tastiest1 lg] tat—ea Bt-Ifl C_i+22 E}+ltl2 21.} Which is the arrangement of ethanol tEtUH}. dimetltyl ether tDiMe} and the combustion products {P} in terms of relaLit-‘e rial-l“ [EQ 24.2]? A} B] EttJH P ans DiMe FtDH P DiMe P l'JIiMe EIDH ELDH 23.} 1lit-’l'iieh combustion would release more energy"? [CQ 25.4] A} it] mole ethanol in excess [)2'? B) It} ntole oldintethyl ether in excess 02'? D} 0.5 mole {limethyl ether in excess 01. F.) A and B release the same amount of energy. 24.} ll'yoti consume ethanol at 25°C it reacts with oxygen in your body to term carbon dioxide and water {both ol'whieh you exhale}. The products you exhale then cool to carbon dioxide gas and lirgtiti water at 259C. How does this process compete with the combustion of ethanol in the laboratory where the products and reactants are also compared at EEUC‘? A} The laboratory combustion has a larger at |. B} The reaction in your body has a larger all. C l The free energy released by the reaction in your body is la: er. D} so and an are the same for the laboratory combustion and in your hotly. E] No comparison of energy functions for different the two processes can he made. Page T The table from page 6 it? re eated here for your exam—taking etmvenlenee. Cempeu ad Ahhreviatien AH = r (1" arm alien} -' 11‘5va (eembuatiun) _rkrrmen ‘ ethane! {g} l - ' 42?! tC‘I—I-fiI—IEDH] ' _ _ _ m __ w u} dimethyl ether {g} Bible —I 3’23 _ t lea-teen}; i earthen Eliflxlt'lll {g} nag-1 JCDfl WP ' wag!) (H 4-36 - - F.— 25_} (4 pt) What is Mfrtthe enthalpy el'l'errnatien} l'er ethanel {kamel} JHW 6.515. 15.51]? a , Ear LIJ-EL +'- M: = iaHF (Products) - Ems: (“Wm magnum at; + Z rat-t: = 3(a); + MHZCD *- (EtUH) Elfin A“? “3'5 #tflt = 2&3?th Entr 1%?" EtGH unite AF; +05 = a Etna 5% att=r= “EB % 26.] {5 pt} Calculate s‘tH”; [the enthalpy nt'eemhustien} for ethanol from average bend energies (average bend enthalpies are an the reverse of tlte periodic table handout} [Hl‘rfi-Tll‘? Farming. +t H. i e GH+ED $36.0 +3 0 ma. ntmaaa + furl-3,1 H1 2 1‘. H1 0 11H:- +clat. —l~,-cao-H + 50:0 —‘?2 GMT—"‘5' * 3H” EH mat-5 aH: Haj 3H: = €81er34" (Cw?) + (ti-re?) + (cl—H“) + 3(0 = of, lnm’mry al- tunda +t {Mam} + athTl = 5 (4m + 54? + eat + «M t 3W?) - La (that) + tniato‘lll = atria - were 27".) {4 pt) Does the value ef' rttH'; far ethane! ealeulatecl from average brand enthalpies agree. with the 1value in the table [explain in 21] words or less}? Explanation: Ha. bond» enfiaaipiaa are areragea ever my Molecules so thee: aetde agree. em.an with He33‘5 Law of experiment Page 3 33.} A lflt} kg blaek nt‘irrm is rlrapped into a small eepper kettle tmass seas g] cantaiaing, and in thermal equilibrium with, tflflfl g 01' water at 15°C. The maximum final temperature reached in the kettle. water. irea system is EST. The heat capacity al'iran metal is 1145 JIgK; cepper metal is [3.51 JIgK. The heat capacity efwater is $134.1.th [H‘Wr 6. t5] 3"} [4 P1} Haw much heat is transferred from the iron? AT: 55-25=30 t4 J Gt r mCFaT = {too.0§t{"’r.t34§rfi)(5e5 a) = IZEEZ .3 H10 AT : {Seaasflefit 597.5336 K) = asset J q: H—I‘tZJ = HooraJ I3] {4 pt} What percentage afthe heat is trtmst‘erred ta the eapper kettte'? = C. aitlL-L m P fiat); __, fl it, - Zq‘df‘; 1¥H1 ‘tma out] = 3": C‘} t 4 pt} What Was the initial temperature of the ircnt'ir : m (1P AT {he \(a 4a 30“? t't-t‘tZJ = 00033 - at“ swat-Smelt 1:513 C- Page 9 39.} For the fellewing questions. euusider the fellewing exuthermie reaeliun taking place in a large sealed eenlairier uL193K where ihe equilibrium eenstani K = 25. 2 CH4 (gl + 33 {5‘1 4-1 2 CS: (I) 'i- 4 1115 Lei A} {4 pi} What is the expressiun lbr Q fur the reaeliun‘? [1-193 9.5] B} {15 p1} Cumplele the fellow—lug table that Lleseribes lhe ei'l'eel ei'varieus ehanges un an equilibrium mixture efthe reaetien initially at 298K. K1 is the equilibrium eunstaru befure the change ueuurs. [Hill-lr 9.92. 9.?3- 9.95- 9. I09- CQ 39.1. 3112. 33.3 i're duets lnere use . Decrease I increase Reduee velume Dee reaSe Increase-Hal pressure by I' Q :- Ki . adfimg '1!” {g} Reaetanls Decrease ' M ' Add 53 {s} Q i=- Ki Prerluets Increase I Reaetams De ere ase Inereu se Q *1 K; Ne Change 1 Ne Change | Pruduers I Inere ase C) {ti pl} 1iii-'hul is the equilibrium pressure ungS a1298 K ifat equilibrium the pressure of E‘lll is 5.43 a1m and 19 g nl'Sg and l5 ml ul‘CS; are present? [HW 929] 4 e 1* - 5_ di- -5.2ld:l?m "pig =25 qufi_26( s3 rim} Page ill «Hm:- El Quantum: Thermodynamics: E 2 1w LEG” = fiH” - 133° 3“. = c m—I” = Z aH°,— {products} - E fiHUI-{rcamams} 3+. dufimwx h I p = h I nu; :35” 7 Z 3” {products} - E S”{rcactm115) Lk.,.{cw]=t1v ~ t1? = hv - Iw“ M3” = Z aG“I-{pl'odLlcts} F E afiflglfircacmnts] Z2 s r k Inw E,.=— .R. B H‘ 55 = qme’T P : In"! W = " Pun-’3‘"! Particfc in a box {14.) Quantum}: for ah + b3 :1» CC. + (ID E = hznla’BmLJ ; 11 = ]. 2. 3... 1 ..- “I ,". . gm Atequilibrium. Q=K ‘Hbratlonal: [Army E... = {v + m man; A =(kfn1}h as am + Rm Q Rotationaf: 1 1 G = G: -|- RTllnm}: a = activity TWT’“ Err "fEA]I'[A]° E, = nfin + 11113.8 = WEE—I; 1 = Emr' AG” '— - RTln K m = mamafiima + ma] Ideal Gas: :35” = - nFfilE‘” P‘J =I1RT .fl'E = fiE‘.” — {RTan} inQ q M!“ ] as” F” 2 n R :r' R = ikhlrm vans: M _ _ _ _ Constants: “ _ [MR1 Ptuml = I’m '* P13 = Kim: " XEPEIU Acid Base: pH - lngLHgff'l N” = 5.02214 x 11:}13 met" R. = 2.1?9374 x m'ml IL. = 128934 )1 m'5 Hz k=l.38flfifix1U'EJK" px=-angx h = HEZEUB x 104415 __ l [A -1 m.=9.101939xm‘“kg FHZP‘F‘” “gum c = 1.99m x 10“ m 5'1 K fi T[K]=T{Cj+3?3.li ""3 95' F = $5.435 I: r rrmI [A11 = was” i V = 1 MC in[.fi.]r=i11la’1]n— k1 * T .‘f .- 033 L am an! E i I”: ; imam R=3.3]451JK'mol' I _ .1 ,_1 _|_ “[31]; = “[AJU + k1. R = SEDSTE x ICI‘ L arm k mu] Hm“ 1nrn=1|qum kzfle 1 m = man} J lnliky'rkfl = Eae’Ri: HT: — 1m} 1 atm = T60 mm 11:! = Tfifl torr 1'1 bar ._ “I: I; . 1 L arm 3 NH} .1 th— 1 [Funk Page ] I in: = [AME ...
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This homework help was uploaded on 04/03/2008 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at University of California, Berkeley.

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Midterm 3 Key - Chemistry 1A, Feii 2006 Midterm 3, Version...

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