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LQ1 Fa04 - CHEMISTRY 322/5aL ~4kfifimififihéOT—%GG¢...

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Unformatted text preview: CHEMISTRY 322/5aL ~4kfifimififihéOT—%GG¢ ¥%$$~3004— [0M 071(14, @fi’ér FIRST LAB QUIZ -— fl // 0f K E Y ”f: NAME l.(ll) 2. (8) Lab time 3.(10) T.A. 4.(ll) 5. (9) This test comprises this page 6. (6) and seven numbered pages. 7.(1o) TOTAL (65) If a question says to answer in fewer than a certain number of words, DO SO——deduction for wordiness. 1A5 will have quizzes at (make—up) labs and office hours. Labs Nov 10 — Nov lg'are make-up only; TAs will stay one half hour if no one is doing a lab. Morning labs convene at gigg. GC make— —up will be only Mon Nov 15‘, 6:00 p. m. For grading questions on this test, SEE YOUR TA FIRST. -1- 1:” 1. (2) A 24/40 male (inner) standard taper joint haé7a 1. 5 mm thick wall. Calculate its narrow end inside diameter (ID). QB 2 (;+— %)MM: 3.6 MM «Io \/ 12.0 [.zo—- 10.45)}... 17ml 2. (2) Calculate the thickness of an O—ring of ID - 6 mm, OD r (w ~‘\(2) The solubility, W/Wsoln' for Water (MW = 18) in an Org o v 1 q. a MJMW = 90) is 1. 0%. Using the simplest dilute soln approx " c.’*- -te the mole percent W in the o - ‘ 1 4. (3) A bottle's partly torn off label says "4-Methy pentan...". ‘ The carefully dried liquid contents' IR spectrum shows strong '1 absorption from 3100 — 2600 cm"1 and at 1720 cm'l. Assuming the liquid is a single mong_ungtig_g_ compound, tell its ‘0 “C 0" likely identity; give reasoning (< 15 words). -o(.ov- ;( :7 m 400,4,- WZ (42 LIL-Myl- be” MMOR QCI‘ . 5. (2) An aqueous solution made from 35.0 mL isopropyl alcohol (IPA, d = 0.78) is "salted out". The resulting 35.3—mL Upper Layer weighs 30.0 9. Using the table below, calculate ONLY the mass of IPA in the UL. ZERO Hg: for doing any OTHER problem. paw/(I%ML 3 i333:— 30$!” 3r3mt :5 .‘A winery, rM é) a tfl: a élLtw 3&0 K07¢f ”are: de. E P t 8 E 5 as D—l 83533335353353.8531 §§§§§§§§§§§§§ ssssg§°"°“”“‘ 6. (2) /OJ7 12"’ SE: Note the diagram, suppos— edly the normal pressure liq—vapor phase diagram for cyclohexane(CH)/fur— fural. In < 15 words, tell why it must be incorrect by considering what vapor it says is in equilibrium with boiling solns of XCH>0.25 @10er 1? MM 93, N0 069mm V‘A w/z WWM wig? 501% 552.13% Mujgm /t‘wc(mfw1um/)) 7. (6) Recall that [SVP per degree, dP/dT, = P(£1§;ap/RT). Acetone‘s nbp (bp760 torr) = 56.5°C (329.7 K); take [X 21.5 cal/(mole-K). A tilde, Nfl means per mole. .J N O 0.5 015,-, Mole fraction of cycIohexane ( X C H ) fl Svap ’ (a)(3) Calculate dP/dT (3 sig figs) at nbp; take R = 1.98 cal/mole—K. ‘1. ,Show that the units come out as torr/K. / ’ 93:5? - 1LS'WK fl ' P fir ' 760 EON {.‘l‘égl ,6-7117C {:ow : 13.0 E" (b)(3) A solution of a non-volatile solute (NVS) in acetone has a cone in mole fraction terms, XNVS' = 0.050. Assuming dP/dT is constant and that acetone obeys Raoult's Law, calculate the nbp of the solution. (First calculate Xacn' then the VPsoln at pure acn's nbp, then apply the result of (a) to the soln.) @ Xmu 7-: W000 “ KAN/f '5 1.000 “0.0” : W/Xa/u 7‘ 7é07L'WK 0'95: 72?,7Lwr Mr ,@ r M 7‘» W 4'0 W4 7/ [BU/322:3 -mww W *7” a A!” 1 a ,9 .. ml :2 A, (#763 a): 3127+“? 33/.LK / 8. (3) 9. (7) CaC12 (a)(2) (b)(2) (C)(3) -3- pj Z:[O de A steam distills at a mixture hp at which P°W = 8/9 the external pressure. (1) Calculate the ratio, molesW/molesA, in the distillate. (2) If the distillate has 17 9A per 18 gw, i.e., per mole W, calculate the molecular wt of A. NCOW‘ %: £:/(mjwvf8’) Notelthe data below. "m—n" in the left column means "a mix— ture of CaClZ'm H20 and CaClz'n H20 in equilibrium". hydrate mixture Relative humidity (rh), % 0-1 1.25 1—2 4.2 2-4 14 4—. 21 The solubility of W in an Organic Solution is 4.0 g/L. One has 100 mL of W-satd OS, which also has 3.0 g W droplets. On adding 3 — 4 g CaClz, it forms a clumpy solid plus some gooey aq soln. Calculate the final mass of W in the 100 mL 0 . (aunt : WWK (00 ML w—M/ 05 m 4.ng aw (eta/m. (9.40; x 0550- 0410 (7 CM M] The OS is separated from the solid and aq soln. A new ow capacity, only 0.015 gW/gDA, but Very Efficient Drying Agent is added. Calculate how much VEDA is needed to dry the CaClza treated soln above, assuming it removes all the water. 304W: %" =(¥.0(7 0/4 0.0M- aufymr Leslie the Lab Loser (L3) decided to save time by using enough VEDA to remove all the W completely in one step. Calculate gVEDA needed just to remove the W droplets from the original mixture and tell why L3 lost nearly all his/her os. 10. 1?¥. '1‘.. mass in proportion. For two rinse-and-spins, calculate n for P l1 \ Cfinal = 0.10 CO. (n is not necessarily a w le number.) {em MAqu (3) An unrinsed Single Laundry Load (SL) retains 8.0% soln on spin fi?<- drying with detergent residue per megs = CO. A Multiple Load - of size n-SL retains soln fraction and detergent residue per fd/O comp/CY (.4446 = V\ Co [‘4 (F'S’eu)j :31? /7.10§.= m, nzo.ox)j"[email protected]fl£)”m3 ‘06“ £1 95"" $ (‘4 a 2'5“ 12. 13. (2) Methyl t-butyl ether (MTBE), bp = 55°, is often a convenient solvent for extracting organics from aq soln. To isolate an organic from MTBE easily by distillation, how should it differ substantially from MTBE? Answer in <10 words. (f6 SMM X61994 suéfléusz/é) C/Vt ~ (3) Pure J melts at 91°; pure K melts at 95°; a certain sample X melts 84° - 88°. A mixture of equal parts J and X melts 72° - 74°; a similar mixture of K and X melts 86° - 89°. Tell what these data say about the likely major constituent of X. Give your reasoning coneisely; use no more than 15 words. xo. / 4 {c “WWW: KhK JM7 ‘5 MP. 61 (3) A solid sample comprises 11.0 g M and 7.0 g N, whose solubili— ties in a solvent S, bp = 65°, are independent. The solubili- ty of each in he; S is 10.0 g per 100 g S. In cgld S, M's solubility is 2.0 g per 100 g S; N is twice as soluble. The entire sample is dissolved in 200 g hot S and then cooled. Calculate how much each of M and N precipitate; pet e nem- ber in each blank. NO credit without calculation/explanation. 7 9M 1003 éoZ/ 5 «MW [Lodz 414.0% Ms? 73M??- th (fled: a»; &u(/ S a}: 6/ be M #200 {cud/5M I— {:a£n Wm? 14. (3) In the "The Wizard of 02", Wicked Witch of the West (WWW) is very Water—soluble. Assume at 22°, a satd soln has 50 kg WWW in 5 kg W. Restate this fact in terms of mp depression by giving a wt % W added to WWW to lower her mp to a certain value. Use <15 words; zero if refer to soln or solubility. 15. tone or with AgNO3 in EtOH, giving one equivalent of an organic product. Write the structure of the principal organic product formed in each case. If and only if reaction occurs at a stereocenter, state whether the center retains, ____q_,_____.r_______. _ _ racemizes, or inverts; otherw1se write."NA". _——————-———_——'—~ 933 NaI in acn ————— > 1 NaBr¢ + org prod (R)-Br-C—CH2—CH2—CH2-Br I AgNO in EtOH ————> 1 A Br + org prod CH2CH3 3 3 Stereochem ( ;( Product «J (a) NaI in . I v A) acetone (,6) gr“ ‘C C [7/1, C(fl/Lcylr @E’C Product Stereochem (b) A9N03 in Et 0 "C"(f/'LC#1,C#L€P waamm 95% EtOH \_____,...—- l‘ / -6- ltfzaé 16. (16 pts, 6 on this page, 10 on the next) Recall the n-BuI prep: acetone n—BuBr + NaI ——————-——€>‘ MW = 137 FW 150 (a)(4) Suppose one is confident of obtaining a 40% yield and wants to get at least 30 mmol n—BuI. Calculate the minimum volume (in mL) of n—BuBr (limiting) which one must use to assure this result. You may leave your answer factored. lama/n- mm: MM.» MAR 30 j“; C9'HF MKN¢~4t H‘flfitzl 75mm £5ng ”Min-fl-ir WL. Avg“, gr __ 0,075‘674D177g/701 ~ 1.7,? Jul. (b)(2) Circle one phrase: Acetone helps the reaction by solvating—- the Br in n-BuBr so it leaves easily. the I in n—BuI so it bonds easily. the I” so it is reactive. e Na+ so I' is reactive. the Na+ so NaBr can precipitate. the Br" so NaBr can precipitate. 16. (contd) - 7 - flj icfo (c) (10) R a i n Ag (kgal) (1) n-Bu-Br ----> Q-Bu+ + Br' + 178 (2) NaI --—-> Na+ + 1‘ + 164 (3) Q—Bu+ + 1’ ———-> Q—Bu—I — 171 (4) Na+ + Br' -—--> NaBr — 174.5 Sum(Br): n—Bu—Br + NaI ——-—> n—Bu-I + NaBr — 3.5 Keqzzoo (5) NaCl —---> Na+ + c1" + 183 (6) Q-Bu-Cl ——--> g—Bu+ + c1“ + 185 Sum(C1): n—Bu-Cl + NaI --——> n-Bu—I + NaCl — 5.0 Keq~2000 Sum (1)+(3) I’+ n—Bu—Br ————> g—Bu—I + Br + 7 Sum (6)+(3) I”+ n-Bu-Cl --——> n—Bu-I + C1 + 14 (1)(3) Note the overall equilibrium c ing with R-Br compared to fraction of the reactants @J ream—+9 R-Cl. onstants given above for start- For each, tell approx what turn into products at equilibrium. N77. 5% 81(‘9/14/0/ ($3) @ ——+ £1 12000 =2 ~‘i?.‘i5‘% WAM(%L) (2)(4) Given that the rate determining step (rds) is I" + g-Bu—X --—-> Q-Bu-I + X', (i) state in <8 words what the last two ,1 numbers in the [1G column, tell in <12 words what their importance i behavior of the reaction. ” ,1 II + '7 I! and II + 14 N I m “ 14%” are, and (ii) s regarding the 6M “/fl’m Mevm‘w (3)(3) As a practical matt O Ke 's or the last [[d e q (?;?:Z<JEV‘%:f 71¢ Aélf/LM’ W er, which are more important here, the ies? Explain in < 20 words. 0,94me (5%» W104 MS} '> 77% M1 4% Jim/45‘0““?- ...
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