chem1B-spring07-final-Saykally-soln

chem1B-spring07-final-Saykally-soln - Chemistry 1B 907,...

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Unformatted text preview: Chemistry 1B 907, Final Exam Name g E. ‘1’ 1 PART I: Carbon Chemistry and Molecular Design 1. (5 points each) Consider the peptide: phe—glu—ser—pro—leu—gly—trp a) Which residue will exhibit the + charge (at pH ~7)? {3le b) To which residue will the -ser- residue hydrogen bond if the peptide forms an on — helix? h e c) Give the sequence of bases that will code for this peptide in m — RNA. UUL' (qkA- Nit. — CLA~ 00 A — 66 A c wag d) Give the sequences of bases that will produce the above m —.RNA sequence in the transcription process. Mfii — CJT— Tea -- $53-— MAT~ CCY- HUI, e) What are the 3 main differences between DNA and RNA? LTch DNK ‘QCLQW— is) We. W 46/». mch Bewflbm mum m \LNR , is) we. I 2. we owe ‘E‘mt meme. (we Ali-WSon when lit—Mk has email. 3~ DNA \5 meKL’ gems mm more \g senate—wetan 0 Draw the structure of ADP. 0 0 _~ “I in 0 -P~o-i>~©fiwto \ \ 0— H H Chemistry 1B S’07, Final Exam Name KE Y 2 2. (10 points) In a combustion experiment, 3.21 g of a hydrocarbon formed 4.48 g of water and 9.72 g of carbon dioxide. Deduce its empirical formula and state whether it is likely to be an alkane, an alkene, or an alkyne. Explain your reasoning. 4.4%%\MO ‘ “§§1% "’ 0.15" M “LO .-—=-r 0.50 me}? u. ' .Lfiflt n, Mailmofic, €1.1ch CO.L 44.0% a 0.17. NR QL’L 0’3 '2, Toast“ 3 : OMA/a WWI M mellQO 166mm ecmb be, Cam‘s tomb 13 cm 0.1m tam, fwmom Cfiulmr 3. (10 points) A hydrocarbon is 90% carbon by mass and 10% hydrogen by mass and has a molar mass of 40 g-mol“. It decolorizes bromine water, and 1.46 g of the hydrocarbon reacts with 1.60 L of hydrogen (measured at STP) in the presence of a nickel catalyst. Write the molecular formula of the hydrocarbon and the structural formulas of two possible isomers. (Egonmm3 meg 1 \mol‘l \O% ‘ —_ mcfig 11 71.4% M (L } GEN} A, 5A (QM ClFl'OtwrQ h ' r -- C \A is W W mbtnflar s; skews-M ’c Lunar) 11,03th1; . 5 q (“EMU m “it Q.N\\?:;kf\ mfi QM mole. \A‘mx gm - “5% ., orgasms“ Moll (-5114 «why a. : chfim\k\‘\olr\ {scant—33x33 am : (3. 04M A (3.9414 mm Wg‘n‘ ~ 2 2n 10005:. J [Whit ~ (A 3 “7X 1 C: L¥\2_\ Chemistry 1B S’07, Final Exam Name 13E 3 3 4. (9 points) Give the systematic name of the following compound. If geometrical isomers are possible, write the names of each one: CH3CH=C(CH3)CH2CH3 \\ C c» 3’ / 5' xx 093 \ ._ U \ / /L h C”\ C-:C_ u QfiOAS “ALI \ LKLLJA 3 CiS - ~2F—kam @4105 ‘" 3" '- 1 " WWW 5. (2 points each) Classify each of the following reactions as (1) an addition reaction, (2) a nucleophilic substitution reaction, (3) an electrophilic substitution reaction, or (4) a condensation reaction: a) the reaction of benzene with Br2 and FeBr LEA than: 9% h e gobgfimoo b) the polymerization of the amino acid glycine - U“ mMax‘ixm c) the hydrogenation of butyne (D elbow-om d) the polymerization of styrene, CHZCHC6H5, by tertiary butyl hydroperoxide, (CH3)3COOH 03 com “:30 e) the reaction of methylamine with butanoic acid mmel‘me Chemistry 1B S’07, F inal Exam Name EE 1 4 6. (5 points each) Consider the cycloheptatrienyl cation (C7H7+): a) Is it aromatic or alaphatic? Explain. mx'moixfio, Ywe, ML 4»\*1 “inc 1005on 1’6” dilemma u b) Why might you expect benzene to be more stable than this molecule? W has. Willa ‘10” awn; 9x 391 Munarfimm' c) What characteristic type of reaction would you expect an aromatic molecule to undergo? mtmmu u GE) 7. (4 points each) Describe the four universal features of living systems (give one sentence of detail for each). a) L'xv'mg) skfigflw's @Mmm 10 (Home otulég a; m bulQoL‘ng) \QQCQXS rem new prfiexf‘g. b) m3 Wm W W (gmwa analog SQLQJWL 0% DER _e Wu “J. swam. 0) film“ W)» m 304% “\Ug'e 5Mu/gwwl 01; MBPHRTF‘ d) LN‘NJS exgsafims 6xsg>l0kg Wm $udo (28 (RM \rxm’wo3 b- swore Chemistry 1B s’07, Final Exam Name 35' BY 5 PART II: Cumulative 1. (5+10+10 points) Methanol, CHSOH, is a clean—burning liquid fuel being considered as a replacement for gasoline. Enthalpy Enthalpy Free Molar of of energy of heat Molar Molar combustion, formation, formation, capacity, entropy, mass, AHC° AHf° AG,° CP,m S ° M -mol‘l k -mol‘l - '1 - ‘1 -K“-mol‘l -K“-mol‘l CH3OHG’rL09 32.04 —726 ——238.86 —l66.27 81.6 126.8 a) Calculate the theoretical yield in kilograms of CO2 produced by the combustion of 1.00 L of methanol (of density 0.791 g-cm‘3) and compare it with the 2.16 kg of CO2 generated by the combustion of 1.00 L of octane. Which fuel contributes more CO2 per liter to the atmosphere when burned? [Assume a combustion temperature of 2500K] flange“ to? \* golkq'g —*-5' 2031ch Jr qglengy \Ls \mL . - QOQKCJQQU‘A \L \ML ' on A - WM — 14 4 (“ch 3‘35)“ ‘lq‘x 30 31.033 ” ‘ ' wSQCDL ,b\flwa _ ma mo“- M 44 ’ loge-1% "vet‘kafa 147* Morch U30“ ' were (0,, CW gmbw Mom col gar gnaw Jan 'Jdm Womb w Mmgq mm b) Calculate the energy equivalent (EE) of methanol. M3, = 159: ~ 7 LS L5 55 = em: ‘Q/mcsM — Lagoon} ( one?) (can) nfi —. -\t>’~l55 L3/“on mon (1:0 q VA EEJ: (-\OL\BM/M\L figuk xii} = @170 Chemistry 1B s’07, Final Exam Name g E: 6 'c) Calculate the maximum total work that can be obtained by burning 1.00 L of methanol at 2500K. meow 2 Na *' WW new ; mm: — mU M: M1443: was 1 ’Kl‘). .wwsjgcsm ‘VM 0&st = ~1Sko,l9‘i4 s ~—=> -— 293m“): YA Wm 1 (am: “fwd; )LMAWO + b 25:19 .1 \LS3 ’4 (1519 7’»qu L5 2. (5+10+10+5 points) Gold, and Diamond are prototypes for metals, semiconductors, and insulators, respectively. 3) Sketch and label their energy band diagrams, specifying the band gaps (eV)? i: Elia; :3]r¢\} goal % [g lGJJ Sil.‘coA kin-Mont} b) Describe their respective crystal structures. (“(51 “P (M F“) 5'.‘|“‘0A,' ‘ QHoAJ Inhifql a fC( A+°MS :A a" +¢+rflL(J(q\ kale; Di‘hfibna.’ "Aha-Mon) latih‘ccf‘ " (CL am .‘A "i +ACQ'I-(LGA/‘R1L‘0LLS Chemistry 1B S’07, Final Exam Name C) Calculate the packing fraction for the gold lattice. CC. q, A lb—-—_o q :1 3 a“ +4“ : (‘Irlq‘ VJ‘JM/m 2 31" q 2 fir "i {fMSAuL—c ?’ '5 — \j '5 3 _ 't. q " 3 r “5‘ We“ «M41 Ha '3 ,. ———-’1Tr ?Q c l‘u 9*‘4‘3’1 1 - '7" j 334‘ r,5 d) Explain why gold is so inert. “U419”; 51%”! ar< .. (:1th of ‘1; orLilalj techs“: 5L;.<U:Aj or? AA’C/ LLl-Ulronsl (At-51“) 4’1“- quiK)’ +9 )<I-r<-i$4. am) (WA-«u. "flhv‘ka TL” :‘ 1L4. lsALw;¢); coa‘\'r4¢hzor\, Chemistry 1B S’07, Final Exam Name 8 3. (15 points) HO2 is a highly reactive chemical species that plays a role in atmospheric chemistry. The rate of the gas—phase reaction H02(g) + H02(8) _’ H202(g) + 02(8) is second order in [H02], with a rate constant at 25°C of 1.4 x 109 L mol" s". Suppose some HO2 with an initial concentration of 2.0 x10‘8 M could be confined at 25°C. Calculate the concentration that would remain after 1.0 s, assuming no other reactions take place. 1 mc c KfNoufi $¢(AA>’o/-.J¢r rn"c q (IQ. [Alt - l * “DU. 2.6 1rto‘ 'M l " (l-‘l'loks )(l 5X10 1(0‘7/fl) Ll :7 (“glaciat‘m/V‘ 4. (5 points each) Consider the Fullerene C34: a) The number of pentagons is l 7- b) The number of hexagons is 3 2" c) The number of dangling bonds is o d) The hybridization of each carbon is 531 . C) Is this molecule superaromatic? Explain. Vt}, gllaws 4F»,Mklfl (flag-(‘3M WL‘J,‘ “1‘1 Chemistry 1B S’07, Final Exam Name 9 5. (10+5+5 points) Ethane dissociates into methyl radicals at 700°C with a rate constant k = 5.5 x 104 s“. a) Determine the rate constant at 500°C, given that the activation energy of the reaction is 384 kJ-mol". I E. ,L-,L A%=7(T T) ' _ 35H mm!" ,‘x -,,——.' ) 1‘- - _,_~______ 1% f.‘.’l°-“ s" lone-3!" “1-”.(‘l k" I K :' 2.3"YIO'45'4 b) What type of reaction would ethane be expected to exhibit with bromine molecules in the gas phase? 5.4!) JJC’IIK'IW‘OA Chemistry 1B S’07, Final Exam Name 10 c) How would you prepare ethylene (ethene) from ethane? rt‘¢‘\’ €01.03 6. (10+10+5+15 points each) The body functions as a kind of fuel cell that uses oxygen from the air to oxidize glucose at a temperature of 37°C: CanOsWD + 6 02(g) —> 6 C02(g) + 6 H200) Enthalpy Enthalpy Free Molar of of energy of heat Molar Molar combustion, formation, formation, capacity, entropy, mass, AHc° AH f° AG.° C)»,m S ° C6H1206(s), glucose 180.15 —2808 —1268 —910 — 212 C6H1206(aq) 180.15 — — —9 17 — — C6H1206(s), fructose 180.15 —28 10 —1266 — - — C12H2201,(s), sucrose 342.29 —5645 —2222 —1545 6 — 360 a) During normal activity, a person uses the equivalent of about 10 M] of energy a day. Assume that this value represents AG, and assuming that all the energy that we use arises from the reduction of O2 in the glucose oxidation reaction, estimate the resulting average electrical current flowing through your body in the course of a day. r=I\/ L v ,1 meow) (Qua PM)” 51A) l13V I: = 17A ./’—~ Chemistry 1B S’07, Final Exam Name 5) C) Calculate the power (watts) produced by this process. f, : Ema : ff: ouur- ’HM ,t 10"?" (11KY60*h}(6053 :: “(90W f—‘A Draw the structure of the ring form of glucose. Ho 11 Chemistry 1B S’07, Final Exam Name 12 d) Calculate the cell voltage that could be obtained from a fuel cell employing this reaction under the above conditions. A)SDI :5 «(+5111Y 99" +0 )5 (fobkm LDf/‘c'i'txl' n5 gk 30"" 'Hu. ft.Jl(a, answer“ in us< «no.ka FLU U'IDH' 15f 4L ‘E‘fl‘ g’léh’} HEY" o .. 1' ' a: C 0‘1- 73¢): 463‘? ~ ‘0 j] 46"“ 14Htw’aqileo.‘ S-‘Au. A S q: o ( A S 1” M (‘4‘ ) .7. Q, ._ _ _‘ lo '3' _ _ . a A M‘ 13°3 — 7‘,“°‘T " 1Q Mo‘ slut...“ Othtz‘AW A ‘ll so 7. (10+5+10 points) Given the following mechanism for catalysis of a substrate (S) by an enzyme (E) to yield a product (P): A.“ 1 A ,__w L kl (I «3 PA“ (t F? E+S<—>ES €°=WMV —1 k2 ES —> E + P a) Derive the expression for the rate of formation of P in terms of total enzyme concentration [E]0 = [E] + [ES] and the Michaelis constant Km = l Kala: gr“ 1 ktfe-S’l 51: A ~ ['65 skttt,—s>nt¢: «BEES-3: a». Kazan} LIES} h j {65’}: Ktr61{5] K14K-. ivx vino-m; .4‘ [‘5']- : fej+arsj 2) (“(51.ij — K.‘[EJ:[ - k1 (€53~ Mafia] [E51 = Milk] 2 (£1.83 K. CS] tang) (5'1 + KM K1f€1.f53 [5] ‘1 KM fl.— 5" 214* G Chemistry 1B S’07, Final Exam Name 13 'b) Sketch a graph of the product formation rate versus substrate concentration. (5’) c) The rates of enzyme catalysis can be lowered by the presence of inhibitor molecules 1, which bind to the active site of the enzyme. This adds the following additional step to the reaction mechanism: k E+I 12-: El (fast equilibrium) 3 Determine the effect of the presence of inhibitor at total concentration [I]0 = [I] +[EI] on the rate expression for formation of products derived at the end of this chapter. [a]: [E]. - [as] - [€11 = [€36 - (e51 ~ ‘52 [2:1ij 1% [2—1 2 {51 via] 1* '53 f1] 14—1 5 “1° {flan («frcs Sfcn. 4g” S 3 (an 1 M was raw “1‘”? 14,231 a» (2 ~* .‘51 [11)44422) E": if “‘17 «(flats szir‘5510rt 4"" r6] ‘- \ Chemistry 1B S’07, Final Exam Name 14 8. (10 points) Describe the two classes of explosions demonstrated in class and give an example of each. 1, C144,. Zoaoliovxs (In; r‘e‘h‘cxl cL‘iA W‘Ltnis‘m3 Lt. H1. +07. '5 _ ‘ . (Am! £nhL~5430n r761.) CH” 4' OZ '4) - ~ - 1' TL‘l‘M‘l Kc’fl °\ 6sz L.<_ CS rNo -’> (any Shiit)”1‘i't¢i'2 ‘KribS(.DV\> 9. (10 points) The typical potassium ion concentration in the fluid outside a cell is 0.0050 M, whereas that inside a muscle cell is 0.15 M. In active transport, cells use free energy stored in ATP to move ions in the direction opposite their spontaneous direction of flow at body temperature (37°C). Calculate the cost in free energy to move 1.00 mol K+ through the cell wall by active transport. Assume no change in K+ concentrations during this process. State any other assumptions. A4,”: cfiTflnQ ’Iry‘ : — s.m¥:....r’z<" (3man Sign 1 -~ TMoi.l 40 ma‘rk 2 Mil :2) j “’23 ’2 8&06 A quvufiior‘ 5 : ...
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chem1B-spring07-final-Saykally-soln - Chemistry 1B 907,...

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