118AWin16MT1Key - Chemistry 118A Winter 2016 First Midterm...

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Unformatted text preview: Chemistry 118A Winter 2016 First Midterm Friday Jan. 29‘“, 2016 Instructor: Lievens This exam contains seven (7) pages. Please make sure that your copy contains all seven pages. If there is a problem, please tell the exam administrator prior to beginning. Please answer all questions. Remember that U. C. Davis Code of Academic Conduct applies to this exam and all other graded work in this class. No books, notes, calculators, models or other aids are permitted. Please turn cell phones OFF. Name: i/ Last First MI Student ID. # Circle your TA/discussion section: B01 -— Ferndnda, Tue 6:10-7:30 pm B04 — Kayla, Wed 7 :30—8:50 am 802 — Fernanda, Fri 7 :30—8:50 am B05 — Kayla, Tue 7 :30—8z50 am B03 — Fernanda, Thu 6:10-7 :30 pm B06 — Kayla, Thu 7:10-8:30 pm Total 165 3°! 1. Vocabulary: Wpts) Fill in the blanks with the appropriate vocabulary word. If two words are given circle the correct one. A) Rotamers Where the bonds on adjacent atoms are aligned are éclipsed)staggered / anti / gauche and are generally higheD lower in energy than rotamers with unaligned bonds due to £3553on [edmsms Siam B) Very exothermic reactions tend to havO earl late transition states and be selective / we in what products are formed. C) Ring strain IS made up of bond 0.4541 and (5 on C it 5175 strains and is smallest for rings with (4 atoms when they are in the Q ,Wu P conformer. D) sp3 / sp2 @rbitals have the largest percentage of s orbital, this makes for longer /®nd @ weaker bonds. E) Sigma bonds exist above and below directly betwee the line of the atoms and are made b®@ side to sideq p orbitals. They tend to b®eaker / the same as pi bonds. « F) An electrophile donates @ (pick one) H+ / @ick one). G) Lewis acids ar®somefimes / never also electrophiles and Bronsted- Lowry bases are®l sometimes / never also nucleophiles H) True False Resonance structures are extreme structures that can be averaged into a resonance hybrid. The resonance hybrid is a realistic model of the system. 1) Circle the substance in each pair that will have the higher boiling point. CH4 vs.( CH3CH2CB; C(CH3)4 vs.(CH3(CH2)3CH3 @. C4H10 J) The overall enthalpy of a halogenation reaction depends on the initiation / @ termination step(s), and is endothermic with F2 / C12 / Br; (I; K) Initiation steps in radical chain reactions start [email protected] / 2 / 3 radicals and end with 0/ 1 @3 radicals and are always / sometimes®xothermio They happen more -qually often as propagation steps. L) A sp2 hybridized carbon forms 0 / 1 / 2%igma bonds and 0 C1) 2 / 3 / 4 pi bonds and will have a b‘rléw planar shape and _2_D__l° bond angles (is M) Was-rmg has exactly 0/ 1 (2/ 3 / 4 substituents that are on th same opposite / unknown side of the ring. N) Delocalization involves at least 0 / 1 / 2 @4 adjacent atoms that have perpendicular @/ any angle 12 type orbitals. 2. Short Answers: A) For each of the following molecules list two functional groups that are present excluding alkanes/cycloalkanes (8 pts) 0 : OH 0 z : SH 3 3 \ I 5 HW 5 WOJ : /\/N\ 3 /\©)\ 4W3! alcokd at kync natal mtqum/ i ester i B") a mine i ___a ”‘m alNhalid: I ' tho)“ maxi}! B) Show the bond-line structures of the following molecules (4 pts) HCOOCHZCHCHCHZCH(CH3)2 u/l\O/\//\/k 1 Pfealw (CH3CH2)2CHCH2CBr2CHOHCH(CH2CH3)CCCH2CH3 ” P” "M. H g /\ C) Consider the given compounds. Fill in the table with Yes (Y) or No (N) if each compound can be considered as the given type of reagent. The first line is filled in as an example (18 pts). D) Give the hybridization at the indicated atom as sp, spz, sp3, or unhybridized (12 NS) 1‘ / B D / E o l NH2 F \c G H A: GE B= Un C= 637' D= 5.97- E = i F} F 2 SI! G = 5 33 H 2 g I? How many pi bonds are there in the above molecule? 0| How many lone pairs are there on atom A? 2 , B? 3 , F? {1‘ E) Sketch the additional resonance forms of the given structures. Include charges, resonance arrows, and electron movement arrows. Circle the major resonance structure. (12 pts) (6 g (D " '9 6/ N a: | 5’ elect which is the better acid at the boldfaced H in each of the following pairs and give a short phrase describing the chemical principle behind why it’s a better acid. (Why is the pKa lower?). (6 pts). Iv/fio ,. / (AA VS M0” M OH I \, /\/\NH2 “Cy wane EN Cil‘am w 6 H3; no. MM G) For each of the given pairs, indicate which compound is lower in energy as written and give a short phrase describing the chemical principle behind why it’s lower in energy. (12 pts) CHZCH3 (H3030 H , , ‘ HQSIH VS' anh has (€55 Simc Lil/drama H 36 has Imam: the/(m'mqhm‘ Simfix mi m, I65 Maw/aims», SMM lawer Form/me Charge” 5 more slam; raahtfi [EncloZMMIPIor’asebam @ “5' V 1653 YinifS‘Mig (chair) (boat) iPsl‘eq- H) Show the condensed formula of the following molecules (4 pts) O A) % Br TA [65“ wu‘cdu‘i‘. (049204 can, culcc “sz Co N (CH9 cuch, OH B) \ \ OH F o 9 am walnut auscuchzCH OH CH (CHJCHQQLHLI CH2 (1 F (CH3) CH2 C°°H 5 Zpi'ea/ '1 WWW” I) Show the possible products of the following radical reaction and indicate the number of C-H that will give that product and the relative abundance of each product. For each product indicate what would the relative abundance be if F 2, or Brz were used. (25 pts) X2, hV , ???? #ofH= 6' Abund.F= b Abund. Br = #dH=l #fiH=y Abund. F = l-fl Abund. F = ‘13 Abund. Br= [700 Zpl’lsbvci‘um Ipl‘y‘ fi= H l 91" [Abundance- b) J) Write TWO propagation steps for the radical halogenation of methane with C12, include al a propriate substances and arrows. (8 pts) @9 («fl .4 . (ll-1,35 H l 4— C fl; 4' H'Cl "lpt 81.. -l per mm. '6' I Caz/3&3 1’ CHS’CI +cn‘ K) Write TWO termination steps for the radical halogenation of methane (CH4) with C12 include all appropriate substances and arrows. (8 pts) «3 (ll-JED- *CI'C' a) Etta/C? a CH3~CI “2152: I p an. 'pep ‘5 CH3/X/CH5 a CH3CH3, emr, L) There are four possible constitutional isomers of the formula C4H100 that contain ALCOHOLS sketch all four of these structures. (8 pts) 83 em <8 3 N8 88 Ag 33 SS as 2: NS 2: 2: 8 ma ow: 3: $2 28 $2 33 5 a, a a an R E go we S 8 am 3a EN EN SQ Rs q: N: E o: a: we 2: 3 $3 $8 28 :8 Sam $2 33 33 $2 N9: 32 em 5 mm P a: :4 E h 5 on «A g mm a a ow 3 mp R $ R 3 ES 33 SW: 3: §: 32 ES 32 :2 mm 3% up 5 =m E 5 ME 3 a: an as > mm fim om aw ww bv wv mv vv mv mm 03: 8.: SS N30 3.3 38 3% 8% 3mm 3.x 03% am 2 ow «U :N :0 :4 co em :2 am VM Mm mm Hm om am mm 5N om mm Hm 8mg 3&8 2mm wmm :52 as: 88.: am; an; E: as: 8me av: £me 3 2 X 2 a: 3.2 5.2 m C Z O m a w n w m S. E g S <m 2 i 3 fl 2 3585 a: a. 28¢ 2.62:5 wNN mmm am am mm 5 22 32 am m0 wm mm SS :3 pm am mm 2 83 2.3 «U v— 8 2 SE 3% w: 2 S : _ N2; :3 am— mg w m 3 N moi m E ...
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