322as08_lq2_key

322as08_lq2_key - CHEMISTRY 322aL April 28, 2008 SPRING...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHEMISTRY 322aL April 28, 2008 SPRING 2008 SECOND LAB QUIZ V 31/3392 C NAME____£ég;________________ 1.(14L_____ 2.(12) Lab time 3 (14) T.A. TOTAL (40) This test comprises this sheet If told to limit the number of words in an answer, DO so. and three numbered pages. Also, deduction if any part of an answer is nanzresnnnaixe minematicnl Tests will be available from your TA at lab and office hours Apr 28-30, and if you initial here -----> , will be put Out in the Study Room by 5 p.m. Fri May 2. ALL tests, whether in the Study Room or Dr. Ellern's office, will be thrown out on May 23. EINAL Exam is Wed May 7, 11-1:30 in the same rooms as were "all previous exams. ' n - 1. W 0 \ l (9 fwd) l M CH: 2. 1 (7) (a) (3) Regarding the prep of MethylPentenes from 4-methyl—2— pentanol and aq H2804: Use of 70% rather than 60% H2804 yields“ MPs. State whether average carbocation lifetime is longer or shorter in 70% acid, then explain only the 1:91:31 yield results, using <15 words. At most 1 point if any part of your answer is irrelevant to this question. Agave Wgfi (‘M \/0g¢e’r WK 70%) «(fa(. 7776;? M” yr?“ {A (own élc a. m I‘M! 74V 72“?» 4 «4% Mfls WM; 39ml]. (b) (4) Two of the methylpentenes obtained were 2-Me—1 and 2-Me-2. Draw the structures of a gem and of a primary alcohol either of which will react with aq H2804 to give these two methylpentenes as almost the sale products. $43 HO‘C g/v“ C- H a 5,: a K r n a: C J-) iii “E I Iflliiiii ‘ H Ill]? C613“? " (had/1,6413 0H Note the gas chromatogram of the MPs from 4-Me—2—pentanol ------- --> (7) ---.-n-__-__-. (a?) nu? mmias: ii Write MV above the peak associated with 'P the 1119.81". 1913111.: component. (0" aI‘V.‘ P Peak area is taken as "ma-h". Po e k 4, mark its SA“. 6 (M 4d (c) (3) Peaks 6) and Q) are the MPs of question 1(b) . Without knowing their bp's, tell which peak is which MP; give your reason- ing in < 12 words. Assume they come from a conunon intermediate. 1 ‘ 14712-1; @flwfi 1 W Q, (m J/Zé/c 4*» w. W (a) (2) 5 SEE (b) (2) r I III. !I_II_.| I . , .. fl II EEill } bl J k'l I "iii?! ‘i i. - Er III II--- —4 II! 0} L-W—L “Maw "53 iii-- z: %> y! I 5:: IIII DESI ‘I‘ A incr retn time ‘9 o Mme“. _ 2 _ 2 (12 point this page) z 3. (23 In the last lab, you studied the Br2-catalyzed isomerization of I, gig-x-CH=CH-X (X = COOMe) to the tzana isomer, III. The Br—containing radicals II—gauche and II-anti, general struc— ture Br-fH——-$Ho , are intermediates. X X (a)(2) Based on how one of the rxn mixts exposed to light behaved, tell how one knows that light alone does not cause rxn. Answer only THIS question, using < 10 words. Mc‘xf [AMOM w‘flt ha i“. Jew-c M (b)(6)(i)(3) Use of either too little or too much Br2 gives a poor yield of the desired product III. Explain in < 20 words. 1‘30 ltfif¢ 6H, (vol (no! lt/fc ’anZ‘fiawa M54464. wnfi-uclzdy/fi (ii)(3) To save both time and materials, tell why it is better to start with too little Br2 than too much (<20 wds). r» M g t {mm WWW; 1/44,: {Z/m fiwfi will: 0 - \ mowk 2V1. (WV (5)41 76W W (37‘ fl” 6 (c)(4) 0.60 mmole Brz (MW = 160) reacts with 2.16 g I (MW = 144). All the Brz is consumed, while 2/3 of the I is converted to III; some I is left unreacted. (1) Calculate the mass of III produced, and (2) the initial mole ratio of I to Br2. @ fulue 1541(1ch M‘de My]: = VJCW] =li/"H'g: 1E], flaw 1+ Page total = 14 pts: 11 for ques 3(d)(e), 3 for ques 4. (d)(8) One can view I a III as two steps: (1) I in DCM,::!III as supercooled liq, Ke = 1; then (2) IIIscl a 111 @xnzxmw. (i)(5) In solution with 60.0 mmol DCM. the sum—3f the mole fractions C}q¢<f' 6F Of I and III = 1/7. i.E. X(I+III) = 1/7. Calculate (1) mmols f~yuc4égf I+III in soln, and (2) mmol solid III obtained from 30 mmol I; note K solid' (1)04 wad ri—flli, (0 MMd(»¢/(/'J W: 0/4, Q 0L ;_<?O'/0}MM( :fl/l’é (ii)(3) Assuming IIIscl is in an ideal soln, calculate/deduce thln, [:7éa based on the data above. Give reasoning. X113“, 2 [5; am h¢(€% rxwé V2.2?) (047 E6: % =? KICsz [‘f' . N M (e)(3)(&Gxnln = -RT 1n thln. The temperature dependence of (KG, A(AG)/AT =(2o cal/mole) /xe1vin=, N45) a A[-RT(1n xxtlnn. Taking T in the term RT (only) as constant, and RT = 600 cal/mole, calculateng, including sign, to change thln from 20 to 40. Note thatAIconstant-f(x)] :- c[Af (1)] . 10 %¢/Klvu 2 “£00 %% \\ [a [Cb-{q K, ‘ ~6oo (0.6% ‘ K Ar- ___’JK(V1 é= 35,, .2») Lo —20.8(C(~N 4. (3) One has a 20% aq soln (w/w) of inxglatile solute A. Calculate 1. the gala fraction one must evaporate to get a 50% soln. You ;é%\ may assume a definite solg massp then generalize your answer. % a: 6twa é=ml+ 8.0.100 .01" WW ’4 9“ Wm) yolk 4941‘, x): “4.77) “W $03 a)? Fa sofa 4,39%“), ...
View Full Document

This note was uploaded on 07/13/2008 for the course CHEM 322AL taught by Professor Jung during the Spring '07 term at USC.

Page1 / 4

322as08_lq2_key - CHEMISTRY 322aL April 28, 2008 SPRING...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online