Exam2-Fall2002 - Chemisfly 322a £32531-2 Exam No...

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Unformatted text preview: Chemisfly 322a £32531 -2- Exam No. 2 (3-) (15) (A) (22) Suppiy the information requested for each of the following reactions. (See information in {he Appendix, as needed). Write yes or no in the ‘oox above the arrow to indicate if reactions (1) - (iv) are spontaneous in the direction shown. 1:1 (v) identify the Lewis acid and Lewis base for the reaction shown. 8 Cutaneous? (i) (ii) v 3-1"; “I conjugate ad‘i conivgate base Sontaneous? (iii) céescazcoo-fia cmgéfia 1+» conjugafe acid conjugate base 0 S In ontarleous? .. H (iv) E Ia g Clagécag + CHSOH C33 CH3 + CflgOH :(jaxi '. '_ :5 \CI; 5 "identify the Lewis acid and Lewis base in reaction (v). "‘I a ‘ V“ + '- (V) CH3LH29H + [LIZCZZ CH3C§§.2“Q*ZI}CZZ dVé‘KaM k'-- ""'v E“;- (B) (3) From information in the Appendix; caicuiate the pr value of ammonia, NHg. Show your simple calcuiation azzd piace yOur answer in the box below. ' I e» a - _ pr swag Chemistry 322a / 325a ~2- Exam No. 2 (1) (15) (A) {22) Supply the information requested for each of the following reactions. (See information in the Appendix, as needed). Write yes or no in the ’oox above the arrow to indicate if reactions (i) - (iv) are spontaneous in the direction shown. L216?) identify the Lewis acid and 'i...ewis base for the reactiorz. shown 5 a outaneous? (2) cegcez'w up cagoia “j" .. conjugate acid conjugaie base Sontaneous? J" \_ conjugate base (iv) M ‘5? _ 1.4+ CH3 C113 + CH3OH 247“! identify the Lewis acid and Lewis base in reaction {v}. ceigcazoe: "in 2:16:12 + _ CH3CHZ~Q~ZIIC12 \‘« ' . ' H (V) (B) (3) From information 111 the Appendix, calculate the pr vaiue of ammonia, NHg, Show yoor simple calculatiorz. and place your answer in the box below - i Chemistry 322a / 325a .3- Exam NO. 2 (2) (20) (A) (22) Provide systematic 0r IUPAC names for the structures, or provide structures inside the boxes for the games, as requested beiow. i ‘-;-“-. "‘3'? _ ‘79. €1.13 * 93H??? 'CH3CH2QHCHZCHCH3 ‘< .j; (3"- \ Cis~2~methyi—3-heptene S~me£hy§4~hexenfl~0§ (B) (8) Provide structures f0: ihe foliowing constitutional isomers of (341-1200 that are identified by their common or alkyl group flames. 2-: -{ - “Duty? aicohoi iert—gutyl alcohol Chemistry 322512’32521 a- Name Exam No. 2 (3) (10) Answer the questions below about the foiiowirrg reaction of acetone and ethyilithium. 51' th 1 th Q m .4» MW Cfiswqwcfls, CHZCHB (A) (4) In the above reaction, {he nucleophfie 38C\’\’3:V‘x\w and the eiectwphiie is 7f.'._.-—————~'. ”" ' In the above reactiorr . : _ the Lewis base 15 Ct: Qx a? """" . arrci the Lewis acié is : J‘s; *\ x. 3 (B) {2) Show the movements of a3}. erectrorr pairs irt the above reaction using the curved arrow formalism Add the curved arrows to the equatron in the above box (C) (a) ’TEThis reaction is rurr in diethyl ether, a nonaqueous soiverrt. Cieariy explain (usirzg information in the Appendix) why this reaction aerator be run ih water. Write a chemical equation in the box beiow that describes what happens in water. .‘ ' , 'V. c _ _ __ . .- .._,°. « f’ a . c '«. .. . z. _ _ '. ‘ L w?" ”\ at“, ’1 ,v,:- __‘JXJ; __ce\ . -‘ . . :. .2 i, ._ K .\ ("'{1‘ . (:1 _fi 1‘- . I. “Q, ._ r- ' "A Mn?- \ ‘=.:--'-" :- - ' : \._...- i. - n ' t___.. . . . - . . . . . f" I I I . \; . v _ .— . r 4 t '. S _ . ._ . . . k“ _ 3“.” \1- __ = _ ' . a g ."1: .\ Mm..." ' \_ “Wag -_ ”m “dwww— ------- reaction in water Chemistry 322a {325a ~5~ NameM Exam No. 2 (4) (20) Circie the correct answer for the fohowirzg statements or questions. (A) The intensity of an mfrared bahd' rs often given in. absorbance units (A) Where Am I01, (10/ I) When an it band shows arr absorb ance of A: 1 at a specified waveIengrh the sampie has absorbed approximately what percentage of the iricideht light at that Iwavelehgfh? _ . _ . .1% 10% 50% 90% \- (I3) Poren'riai Lewis acids among {he structures below are ' {circie answer) Q a + . . m CRTNCHB {BIC} CIIB'QCHB 23?: orrly III I1 and 1VI CH3 Ci CH3 . I, II and III II Iahd III " 1 5 r1 III Iv (C) According to the pKa vaiees, the order of acid strength {strongest to weakest) of the compounds beiow is HI ITIZO CH.3NI”I3+ CHSCQOII (circie answer) sza -30 157 1015 437 I>II>111>1V II IIIIII>II¥21Y>I I I II III IV 1V>IH>II>1.I>IV>IIII>III .I (D) The order of base sirerrgth (strongest Io weakesg) of the chemise} species below is (Him: Refer to the information in the Appendix). II {circie answer) NHs cfiBCHZE} c330}: III-12 IIQIV>III>I 3V>1>13>m I II III IV 1V [113.5111 II>III>IV>I - I a - M- _. .I ' “M 'h. ..... \ -. - :..w- "- ‘- “ - ' '\ I .' 1:" k. "M k " \ (E) The changes ih standard free energy at 250C for the acid dissociatioh of three carhoxyhc acids are given. below. According fo the AG0 vahres, the order of acid strength (srrongest to weakest) is OOH coon COOH IIchIcIlIeI answer) I>II>III :- III>II>I C1 CH3 OH II>1>III I>III>II AG” (Iccai / moi) 5.4. 5.9 6,2? Chemistry 322a 1’ 325a -6- Namewx L33- " - Exam N0. 2 (4) Contd. (F) Amorzg the structure} representatiom for C633,; below, the two structure} formulas that are actually the same constitutionai isomer are CZ--13CH2CH2CH2CH2C§§3 C§~E3CH2CZ~EZQHCH3 CI--EI.3C}%IEQHCH2CH3 {circle answer) I 12 Cit-Z3 (3&3 . :11 fig; __mq___1;I IV and V CH3q1-ECHCI-l3 C—Hacflz‘Ffluh C33C52<§{3H-3 ‘‘‘‘‘ 3 CH3 CHE-Ha CH3 IV V w L,” _. (G) What differeztt types of 1“} are in the structure below? (eireie answer below). fig .. .. 3° 2° arrd 3“ It}; - ._ 105m 20 H. ' 1" arrd. 30 H. CH3 20 and 3" fl. (H) The constitutiorzai isomer of C6H12 that has no ring strain is {Circie Structure beio’w} [f O M O- (1) Tire lumber of different groups of. equivalent H in the aikarle below is (I333 (cireie answer below) @Hfiei‘izCHzCHs two Itour”'--_ five six (I) 1271 the alkane beiow, the C-C bond with the iargest barrier to rotation is 2 (circie arzswer below) if\ \ ~ _{- 1 2 3 CH3WCHrgfi—CH2 .Hg ' ' ;._ (/3313 I 3 Chemistry 3223/3252: -7- Name" _..- _.._m Exam No. 2 {5) {15) The heats of combustion of three constitutional isomers of methyicyciepen’zene have been measured 1:: the Eiquid phase: 1~methyicyciopeniene, AHC: 4396.85 kcailmol 3~methyicyciopen£ene, AHcm @0022 kcaZ/mol. 4-methy]cyclopentene,'AI—icm $01.68 kcalimei (A) (2) 122 the box below, write a baianced general equation for the cembustien reaction of these isomers. baiamed equation for the cembustion reaction ‘\ \.. --,.u ”\l x " .. C6330 "‘1" .5 (B) (6} fievide the structures for the isomers inside the proper boxes, as requested belew. . combustion ““““““ “" products 1 wirmathyicyclo pentene 3~methy§eyeiepentene (B) (7) Show how the heats of combustiozi provide a measure of the relative stabilities of the three isomers by drawing an energy state diagram below. The reiative energy scaie on. the Y-axis is broken for cenvenierzce. Draw and labei the starting arid product states for the combustiozi reactions of the three methylcycéopemenes. Use an arrow to eoneeet each starting state with the product state and indicate the enthaipy change. Clearly indicate the isemer associated with each starting state, and Show the energy differences that measure the reiative stabilities of the isomers. . J’ 1. 900 W .. _ m _e 113153;“? \ " - {'32 i- a ' energy in ikeal /mol 890 ”" ‘The most stabie isemer is K ‘i: Chemistry 322a X325a —8— Exam No. 2 (6) (15) Rotation around. the C—C bond in a disubstituted ethane of general structnre XCHZ—CHZY gives rise to (Eifferent conformations with different energies. (A) (4) For exampie, dating a comptete 3600 rotation around the Cng3 bond in butane, the potentiai energy changes as shown betow The ctiagram. shows that conformations A and B differ by 0. 9 kcal/ mol Draw Newman Projection formalas for conformations A and B in the boxes ta .fs \ 3Akcaiimoi 3X \/ 0 60 120 130 240 300 360 degrees R eta ti on M Relative t’otentiai Energy M» (EM (2) Briefly, why1s conformation A more Hate-tote than conformation B? _ ‘CW (C) (4) In 1,2-ethanediol (“HOG rigor-120m, rotation aroonci. the C-C bond yields anti and gauche conformations where the gauche conformation is more stabie than the anti conformation by 2. 7 keel/mo} Draw the Newman projection formulas of the anti am? a gauche conformation for 1 2—ethat1eciioi. in the correct boxes below a . {-1 _-_-_ _ K \/.._1_..\ t 3“" Newman projection. formulas of HOCHZCHZOH Z,2~ethanediot E’robiem (6) continues on the next page. Chemistry 322ax’325a »9- Name MN \r M:- to?» Exam No. 2 (6) Contd. (D) (5) Studies on 1,2-ctimethoxyethane (CH3OCH2CHZOCH3) infiicate the anti conformation is more stable than the gaactle. What factor coutci explain the energetic preference for the gauche conformatioo m 1 2~ethanedioi? Draw a Newman projection formuia m the box beiow clearly fliustrating your expianation.. _ Kw "-qu ‘\{\.__ k. -.,-‘t _ ._ 3:... “b“; \i '- N g . max/oft: or U) (5) I am a hycirocarbon with the formula C5H3. I12 my infrared spectrum there are characteristic absorptions near 2900 cm'} 3300 cm”1 and 2200 cm 1 I react wrth hydrogerz gas over a piatirzum catatyst to produce another hydrocarbon with the formula ('15ng This hydrocarbon has at} three types of hydrogens: primary, secondary and tertrary. Draw my structure in the box bestow and write my REPAC name on the Ime below the box g;°‘§‘_;£é;t_j:;itf Chemistry 322a/325a ~9- Name \ of} E" w W _‘ Exam No. 2 (6) Contd. (D) (5) Studies on 1,2-dimethoxyeéhaoe (CH3OCH2CHZOCH3) inaiicate the anti conformation is more stable than {he gaoche What factor maid explain the energetic preference for the gauche conformation m 1 2~ethaneciiol? Draw a Newman projectiozz formuia m the box beiow clearly iliusirating your expianation * - - EL“ . ' '5; x . “if” H." {I a. \ {w ‘3. “Y“ \- t {D g \ k Juli: i \3 )4”, "_,_. ‘43 ';)\/*¢¢”\.' ‘ " ' ' - k . k .. - ' J's r k‘ m -".--'2\'k 5“ ' 34% \“K’ .- f 't .- = “\ 'VK'} \ij-JL“ ‘e‘w ‘-._..."‘M.o-.1 * A 3 ““- '- u _" 9 J ' - . - \:r' '. ‘ -"-..'\ ' ' V, ..... -. . - ‘I v___ . .. I _ id" - IIIII l 5“ ./ . gm" I .rf' . . ' . F2. 5' :-..‘ - \JI' 2 PM\ \ - . i (7) (5) I am a hydrocarbon with the formula C5H31n my mfrareci spectrom {here are characteristic absorptions near 2900 cor} 3300 cm”1 and 2200 cm ".1 Ireact with hydrogezz. gas over a piatioum cataiyst to produce another hydrocarbon with the formula C5H12 This hydrocarbon has ail three types of hydrogens: primary, secondary and eeroary. Draw my structure in the box beiowl and write my IUPAC name on fhe line below the box e * x W; j / W «Mm-I: 11‘ j [W ix. x “ V “I / --' \ Amwa- t‘ \q\ .- "Fax ...
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