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322af09_plq1_blank - CHEMISTRY 322/5aL...

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Unformatted text preview: CHEMISTRY 322/5aL , Pfififi—Efififi flMGO‘f—Q. fuéfi'FIRSTL-ABQUIZ ~ fi// «200‘? BY Eflgfi NAME 1. (13) 2.(11) Lab time 3. (9) T.A. 4. (9) 5. (7) This test comprises this page 6.(11) and six numbered pages. TOTAL (60) If a question says to answer in fewer than a certain number of words, DO SO——deduction for wordiness. 3A5 will have quizzes at (make-up) labs and office hours. flfinfirfM$-69'E‘Nuv-4 a1e——make—ap_oalyp-Qfis-wéLL—sbay—enenhalf For grading questions on this test, SEE YOUR TA FIRST. (a)(2) (b)(2) Density g/mL 0.990 0.980 0.960 0.940 0.920 0.900 0.880 0.860 0.840 0.820 0.800 0.790 0.786 (2) (2) (4) (2) (3) -1- A 24/40 male (inner) standard taper joint has wall thickness = 1.5 mm. Calculate the diameter of the largest spherical object which could pass through the joint. In <10 words, state the essential characteristic of an O—ring. Saying "it's round", or equivalent, is worth at most zero. 4—Methyl—2—pentanone is made into 4—methyl-2-pentanol. One wants to check the product for unreacted Starting Material. Near what frequency (cm‘l) in the IR should one look to see if there is considerable unreacted SM (circle one number)? 3800 3400 3000 2800 2200 2000 1700 1500 Does the product sample need to be nearly water-free for this IR test to be useful? Explain your answer in <15 words. A flask is flushed with ether, (C2H5)20, bp = 35°, then drained. Tell whether any liquid film will evaporate faster with the flask neck up, or neck down; explain in <12 words. The effective MW of air = 30, bp ~ -200°. An aq soln containing 27.0 g isopropyl alcohol (IPA, d = 0.79) is "salted out". The resulting 35.7-mL Upper Layer weighs 30.0 9. Calculate the fraction of the original IPA in the UL. IPA.wt% 6.5 13.3 26.2 36.1 45.0 53.5 61.9 70.3 78.7 86.9 94.8 98.6 100.0 - 2 — 1m 6. (3) Note the supposed normal pressure liq-vapor phase diagram for cyclohexane (CH)/furfural. It errs by saying there is no va— por in equilibrium with solns of XCH>0.25. Assume the vapor curve is correct. What must then be true about the liquid curve? I40 Tempelatute (”C) 0.1.5" Mob friction a cvdomxm (X C H) 7. (4) Note the distillation curve below for 100 g of a solution of L (lower boiling) and H. L and H do not form an azeotrope. 'm‘ :===:===::=:=====§==:r.::===:=========::===:===:: 0 M ”47M aa¢d Sffiflpfll I III-I‘ll... III-IIII-IIIIII-IIIIIIlllllp'EEII ====I II.III-IIII-IIII-IIII-IIIIIIIII!!III-',..-l- III-IIIIIIIIII-III-IIII-III!!!Il-Il-'-_----IIII-II III-- I. I III II!II--—-_---—---IIIIIIIIIIIIIIII II... I... IIII 'ZuanflII-II-IIIIIIIIIIII III-III III-II-IIIIIIII!‘I-IIIIIIIIIIIIIIIIIIIIIII III-III IIIII-IIIIIIIIflIIII III-IIIIIII-IIIIIII III-l 60 (0 la Jo lfimfi (3’33": so (00 Below, circle one of the items separated by / in each set. From the curve, the bp of H is at least / at most 393°, and the mixture was about 20 / 25 / 30 / 75 / 90 percent L. 8.(4)(a)(2) Co -':- -n ALcohol, a Ketone flgaasfiéfi§:§::;lic ACid, each having nbp ~ 14i‘2m ........ _;rclem_;~4éorrect descending grdgr of their AVID/degree ___-. ._.. their nbps: AC>AL>/,»JWE;K>AL AL>AC>K AL>K>AICZI"""""""'-~ >AL K>AL>AC (b)(2) Thisflor-T"3rr~g- same as tgesefifilrjof the change on vaporization in théf g siflstate function (circle one): I -3- 9. (2) W(ater) and odorous cpd D are mixed. Two liquid phases exist at equilibrium-—one is 1.0 mole % D, the other is 5.0 mole % W. Assuming that in each phase, Raoult's Law applies to the majority component and Henry's Law to the minority one, give Ptotal for the W—rich phase, in terms of P°w and P°D. Ptot, W-rich phase ‘ 10. (3) de A steam distills at a mixture hp at which P°w = 5/6 the external pressure. (1) Calculate the ratio, molesW/molesA, in the distillate. (2) If the distillate has 12 9A per 6 gw, i.e., per 1/3 mole W, calculate the molecular wt of A. 11. (2) Ethyl acetate, CH3CH20COCH3, bp = 78°, is often used to ex- tract aqueous solutions. Tell in <10 words why it is not suitable for extracting liquids boiling between 60° and 100°. 12. (2) A student has limited extraction data. S/he knows only that extraction of 10 mL of a soln of C with 20 mL Extracting Solvent left 25 times as much C unextracted as did extraction with three.20 mL portions of BS. Given that Fraction Unex- tracted for this case = 1/(1 + z)“, z E K(VB/VA), calculate K. 13. 14. 14. -4- (3) Pure J has mp = 95°; pure K's mp = 92°; a certain sample X melts 84° — 88° and is suspected to be largely J, largely K, or possibly little of either. Mixture mp J and X = 86° - 89°; mmp K and X is 82° — 87°. Giving your reasoning in <15 words, state the likely major component of X. (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 geld S, M's solubility is 1.0 g per 100 g S; N's is 3.0 g per 100 g S. The entire sample is dissolved in 250 9 hot S and then cooled. Calculate how much each of M and N precipitate; pg; a gem; he; in eagh blank. NO credit without calculation/explanation. (3) Wicked Witch of the West (WWW) is very Water-soluble; at 20° a satd aq soln is 75 wt% WWW. Restate this fact in terms of mp depreeeign, stating how many kg W one must add to 45 kg WWW to lower her mp to a certain T. Use <15 words; zero if refer to soln or solubility. 15. (7) Recall the n—BuI prep: acetone g-BuBr + NaI __———_______;.- g—BuI + NaBr¢ MW = 137 FW = 150 MW = 184 d = 1.27 d = 1.61 (a)(4) Suppose one is sure s/he can get a 240% yield and needs at least 10.0 mL Q-BUI. Calculate the minimum mass (in g) of n—BuBr (limiting) one must use to assure this result. (b)(3) The reaction was done by refiluxing, i e., heating under re— flux. Tell what this means and why it is often convenient. Use < 30 words total. 16. (5) Bastien Ag fiscal). (1) n—Bu—Cl ——-—> n—Bu+ + Cl' + 185 (2) n—Bu-I —---> n—Bu+ + 1‘ + 171 (3) LiCl -—-—> Li+ + c1‘ + 199 (4) Lil ———-> Li+ + I“ + 174 ~ , in acetone , (a)(2) Calculate lkern for n—BuCl + L11 ——————————— > n—BuI + L1Cl, assuming that the acetone solvent has no net effect on £fl5. (b)(3) LiCl does no; precipitate here, as NaBr did for n—Bu—Br + NaI in acetone (Pd 7 lab). Explain why the reaction above need not "be driven by precipitation". For simplicity, assume the soln is saturated in both salts; use <20 words. 17.(6) The reactions below give the same principal organic product, as shown: 2% AgNO3 in 95% EtOH rxn 1 (CH3)f"Cl "-fi“-ET———T——E—_E__> eac ion 18 as . 2% AgNO3 in 95% EtOH (CH3)3C O’Et rxn 2 (CH3)2CH—CH2—Br .................... > Reaction is slow. Explain in mechanistic terms: (i) why the product is the ether, not R—ONOZ. (ii) why rxn 2 is much slower than rxn 1, and (iii) how isobutyl bromide gives a L—butyl product. Draw structures, use <50 words——complete mechanism not needed. ...
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