Prelim 2 answers - Name {Last} {First} Cornell Student in...

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Unformatted text preview: Name {Last} {First} Cornell Student in Number th Instructor’s Name (a? Lot} Section (Day and Time} Chemistry 20? Preliminary Examination 2 NoVember 9, zoos Time: T:3[|I PM — 9:011 PM Please do not open the exam until told to do so. 1You have 1.5 hours to complete the exam. This extun has 9 pages, none of them blank. Page 5' shows a periodic: table, the speetroehemieoi series, an important reminder, and the d~orhitai energy.r ordering for a squure pionor complex. Before beginning work, check to make sure your exom is complete. Write directly on these pages. Show off (Jyonr work and imiicote omits where necessary. You mo},r turn in the exam at the front of the room when finished. I. {so} _ 2. (so; _ s. {so} _ 4. {25} __ 5. {so} _ s. {so} _,_ TUTAL {HS} I. [3!] points} Mulecular Geometry {Lewis Structures} Draw the. LflWiS structures for the following molecules. Show all bondad and nun—bonded electrons (with drum and dashes}. assign formal charges to t3th atom. shnw any rest-name structures {indicating 1Whitth is preferred}. and predict the molecular geometry and hand angles. (a) NU“ i- f -_-.- Mun- ' :: 7}- . - - (craft... 0:.) '1 .- __ {Ff - a I". é f/LKrCilaigla-Pai {mm t *O'r "' :- r . __ J . 1‘ .JT/‘g" J.th EJ- . "x'r' “*4 I! H _?r'6-'_)7' H :7 Jrér+ j (2' % f {fl if H J p I, f} r_.'1 {Tu-0;} :- . 1"" _K['IT/(:L:H//r- 21mg J w m ' I \ raj/- ,3 “P” w" “ ' " _ Waiter”, J‘s -_—_ ,.,‘./F'°"'o‘ 'e' ._ . . - - E a J a mm w ,- t a r 1': uflrl‘r :— 3: FJ'II I G (ft-P17: Tl {’L’fiff. f [C] SE; M 6 F '?:’U '- ' i t- ; r I t{Hr—1 I”? Cfar'ufget! :1": III. E;- - :" '3'" I .- " I . . -1- .. -- _ . , I ' II 5;: fr) 6 .L_ I r;- F“ ' 7yfu/J/1flxrfri If" If?“ * 'J. - ' " -. .u I It .I I r E " .--- ’ . I"I 1 rd“- .f-L .I_I .-L—H| 'I_JI _|—'I J K»; I,_ J 2&0 I! (7' (is. 2': |l- :‘l ,I, .. (at) 1am u u“ .‘-" .. w‘ .~ '21:: ‘ e4- . r3? --: (r I ' .5} : .4- I_|' F I J _ 1? c Ira? _ xiii. _ _ _, J _.I 17;!" '1'4-“if-T-‘L'fl’a .'. “5 W J W ' ?' h r n «— "' I'M-mar- ri? r .- {B} hng‘ - Pi J r, ‘I I i "'__2"- f ,1- ft; r‘J r «:r'- f — a f p :1 as It'll; " r/If f (- I I J ’ f r}. 4 _"" . - -.—- If 4 (“P/l If! f Hit/g ( I'. .E ./. _ .f-J“ —- L." ._ J» t t fifwé’r-Uf’f aria-"H .i if, H_r/I-' . / 1-: r:- . , q 2 2. [30 points] Melecular I'Sreumetr'}r and Polarity {VSEPR} (a). Acetic acid, H3CCDDH. gives vinegar its snur taste and pungent smell. Draw a ifiwifi Structure for acetic acid, and indicate the gBflnlfltl’j-r around each Barbee and dxygen atern. :0 : Ff” Tjgdfiifiimrfl' I]; va'imflfu If -._ C I a \ Ire. (i— am M 2? )7 a. U ' ii K £57m? L: 65.34)}: 7317313}? .A’Frm. hi' E . , fl '1 ./ EH flip {fir «131': Eta: :1" u'e’a‘mfir‘ Tf'v'e’g/xg'wfiwyg i I "FX’Mee-rm ‘=" "’7?! 5' '3 flfiimfld {h} Are the following molecules paler? Justify,r your answer with a Lewis structure. . "' F + (p: r ,. ix” r:- 7€xfiwwc {4-9 In _:-r-":-- 1'46} :F':__ 5*- H its—'- 5 re Ii I- 1} -_': Pt? (#:QJ 'J’C‘,‘ I H h 2'0“: H -—~ "firm/Ira? ,v'éflfi'. a. £4" 6'}?th ---— f 6* if C31”; fl/figfii’; h‘i'éTHTflfr; .—= 637$?”— H - foflMfl RES: ngXEij'gfi; a}. Jul (1:?! d {bis-tyrflfi ' ' ' ' Mew»- flew/é: 4. a. O." _ I :g'. .' ; i I. _ I flit-fife) 3% H I f 7£35§L¢JC 5 6:2» 5 H S fifteen-W “E?! i”:- .'¢ Xe" “bf ‘5‘. _. I. '4: '9’. (El. arew' l. .l 0 " I 'r 3. {30 points} Quantum Mechanical Bonding {Molecular Orbital Theory} is} Construct a molecular orbital energy level diagram for C0“. Rank ICC-‘1', CD". CD, and DC!+ in order of decreasing bond strength using bond order. Indicate the magnetism {paramagnetic or diamagnetie] of eaeh compound. ’ *' age-2e? 6'7” : Cg )- C‘b’i Cipfi> {flap—— (b) So far we have made moleeulsr orbitals by combining together 3 orbitals and p orbitals. Consider two atoms that are bonded along the mantis. Suppose that it is possible to make a molecular orbital by taking linear combinations of a ct” orbital on one atom and s p}, orbital on the other atom. Sketeh the resulting bonding and antibontling orbitals. Label the nodes. ff a“ x '2 4. [25 poinlsl Electron Density, Molecular Shape, and Quantum Mechanics (MD. theory & h yhrid izulion} tn} On the homework, you sketched the 132i, orhitaIH for NO‘ and N2. Now sketch the GED orbitals For NIT 51nd N2: fruhéfl of X 91:11.?! 9’ X #2- MP + ,. __ 1r 1 I, M. 5L .. 61$?th :1 w (a; f t 5:1 ,1 F If??? (’- {igerJfifJ .:’t-- Misfit (in: e?- flit” {h} Biaeetyl and neetoin are added to margarine to make it taste more like butter. 0 [J 0 || || || f‘H;~t“—t‘ —t"H3 ('1-[3—f‘1-l—f‘ —f‘H3 l DH fiiacelyl Aeetoin Complete the Lewis structures by drawing in all of the electrons {in both bonds and lone pairs]. Predict t-‘ttlLtet; For all the C-C-D bond angles and give the hybridization of all the carbons 111 the two compounds. How many 13 and how man],r 1: bonds are there in each molecule? :9 .1: )30a (J, 2{ 2:: 120‘ r - _ e 1' i 1' '5: . .4 "' a" ,5, “1 k“ fl ’0 (Eff # l t O I e *4 .st c: ‘C _ C ‘1 1" min / '\ flit“ "“‘—' (A e? I 1’1" ‘1” C 1’1" ' 1' w \ F J ’ J ‘ 7(E! if .. . (A Air :9 . 2'11 . 0. H F If I ) it 1L 1x 3 M J Fr if ,1“) :5 "- 3.4K? 7": ‘19"?1! D .3 v a.” 2 3 2 f R m h? 1;“ 3.11 “I {- __H, F m r. V JP] I" (2%???” CF” 1‘" If a“ w if 7414¢yyn r; 2 s r- /3 W" 5. {3i} pointc} Transition Metal Chemistry C—M M_-—-. [it]: Give the metal‘s coordination number. oxidation state, and ti electron count: 1} “IE-L1]:— _ £24! — 9' ,3 i F9”: IPKE) 0/ 2} [Crtentljch Co = £9 3 +3 0—3::9 Chc’fl?) .' 0X 3} K4 [Fetcmo C? 42’ = 6» 1"5’+_2_+4=g p563?) .'. {b} Draw thc d-orhitcl splitting diagrams for the following complex ions I. Fol" (octahedral. high spin} ?‘ 7‘ in"; Er; L i .11. X3 ye EX 2}[NECI4}1-(tctrahetlrul} f 7‘ infer? “H m" "M M *3 5/1? 2): (av 4‘ a" 3 mi 3-? X4“... (,- .1 3} IzntchtF' If fl no = +2. 1:?- xl—fir 1 if» (a) 7'13.- E It , “No I? if}? Ex 9.. A {mega/41; .3: -5r’r-a ti. {St} paints} Mere Transitirm Metal Chemistry / {a} Cttneitier the tenure planar complex [X (Oi-Ihf“, where X represents a transition mete] of the 4'“ row of the perindic table. Magnetic measurements show that the complex has two spin- uttpaired electrenst. What are the possibilities for X [give the etement, its Oxidatifln State. and r]— clectron mum}? ‘“ fl 1 xfiez; : Kenya. y—L-yl “7712;; all 9r: ' J W7 firfiJ’J/‘zfl’fi: L -— j; fill Cir/2r) or?” re— if“ 3% 0’1.“ We at”: <32" [h] Suppnae that the tetrahedral camp-lea [X {OHM} is paramagnetic, with four spin-unpaired eleetrnna. Here X is the same element as in {a} abet-e. Can you identify the transitirm metal? Again, give the element, its exidatinn state, and tivelectren eeunt. a 7£WH¢?& 2229; W/ ’f E L/ wee/e fixer/ever? grilfifir’ warmth} T If #993?" fig -' ,1: 5,415,; (Tm/2:“) 0"" Mare Transitiun Meta] Chemistry [eunflnuedl {e} 0f the two complexes [CuFbI'L and [Cn{en)3J3+. ene appears yellew and the other appears blue. Match the cemplex to the color. Explain your eheice using words and a color wheel {and :1 dvurhi .Ell ener level :11 re if need :1}. I er a; m e {Erma} “I d 6 f,_ 31‘ K 6’3: F2 ) Men/3‘} é arr/£13 5’: we? (7,5; Man #9101)“ aegis 65"3916a 60 Mair- T T 31 33?; . Imam 2 J5”; 5.x 3;:- .32 If; f”? i)! 7??wa _ 6. we; 9&2 (Head .574 may j I ' ' {if 1,, f -3135: mgr“? 6’3 fflffif fir “REX” if Karla-{UM Q, r Ir we?! _' vi" ' ' I; Periodic Table of the Elements '“ I'! I”; I4 42": 5A. J-u' d 5 b 'u' I 9 ill 55 6|! Hi .ID'JTll' Mom 11:52: :I'Hufi II'.I II 12 Al EB 15 13 . . 22 33 3h 2'1 2! 29 II 3| 3! 13 34 Ti 1' C Fe Co NI {.‘u Zn Ga Ge A! 5e Kr 145559 4?“ I‘LHII 1L?!“ 35m sum sue MM .5pr an: 72.5: 1mm 35'.“ man 3‘} 46 4| 12 4C! 44 4.1- 46 41" 49 :'!(I 5] 5'2 fiil 5-1- ? Zr Nb Mo Te Ru lu- Pd M. [n 5: Sb Te I lie um H.111. Dem-I Ed.“ on Ielm 1mm- HM: Imus; “4|: JIIJII'I mm mm Haw. In.» 13 5-6 5'? 1'2 11 1‘45 '.|'J' 1'3 Til m !.'I 3.5 HIS C: [la 'La HE IR: 0: Ir P: All Hg Bi A: flu. Jute IJT'IH mm m» mum m2 wen lam new: 1mm 2mm mm .131- H? HE. 3|} :04 ms [I]? IDS ILI‘J H [I [ll H 1 Fr R: The 13h Jl Hi: Hn rm Uun Lluu L'uh Ill“ JHJ'I'H mm: 13ml mm mm mm wall 1153: LE: IET‘I'I 5E SD 6:: 6-: a: GI {:31 ‘llrnhaninle 5am: Ce Pr Nd Eu Gd Th Ha Er 1m: Hui-I H4 N lawn ISLE LI: 9:} mum m In 91 '3] 9-1 95 9G 9? ' r.hveIIirllelue serlei: U Np Pu Am Em Bk mm 211 m1 nu. ma} :an mfl #Wl'lifl “iIhIH-fl bfllfl DH urban-11 Harem-1:1 fldieJeIWt EIErI'IErLLI Ihenumhm Illliad [In gunman] m- Ibe MEI-1111mm: enhn mull: mm: intern. The ngetmehemieal series is: CN':ren:wpywNH]>H2030H'3Fhfll'}]31":~l' em = “ENCH1CH2NH3 Remember: the em flip happens; when E E T. The {Lerbitul energy,r erdering for :1 xguare-Elunfll‘ complex is 2 2 2 . . xvy 31w}: ~M.}*e ...
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This note was uploaded on 03/31/2008 for the course CHEM 2070 taught by Professor Chirik,p during the Fall '05 term at Cornell University (Engineering School).

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Prelim 2 answers - Name {Last} {First} Cornell Student in...

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