322a lab quiz 1 spring 06 blank

322a lab quiz 1 spring 06 blank - CHEMISTRY 322aL W m Am Wr...

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Unformatted text preview: CHEMISTRY 322aL W m Am Wr - 6,0591%,27 BY Efigfi NAME 4% L 1. (8)____ 2.(12) Lab time 3.(12) T.A. . _ _ __ 4.(12) 5.(10) 6. (6) TOTAL (60) This test comprises this page and six numbered pages. If a question says to answer in fewer than a certain number of words, DO SO. Deduction for wordiness. 1 have quizzes at and make—up lab. 'n lab convenes at 9:30. For grad' estions, please see yo irst. -1- (2) A 14/20 male (inner) standard taper joint (like those on your distillation apparatus) is made of glass 1.0 mm thick. Calcu- late its Inside Diameter (ID) at its narrow end. (2) A circular groove in a flat piece of material has Outside Diameter = 12 mm, and both width and depth = 1.5 mm. Calcu- late the ID of a non-stretchable O—ring which will just fit. (2) Complete the following sentence, dgfiining the boiling point (in general) of a liquid, A. The bp of A is (2) Below is the distillation curve for a 100 g of a solution of L (lower boiling) and H. There is no azeotrope in this system. o N III-III. III-IIII-IIII-IIIIIIIII-IIIIIII "3 III-IIIIIIIIIIII-IIIIII-II-IIIIIIIIIIIIIIII-I1...-I III-IIIIIIIIIIIIII-II-I-III III-II‘IIHIIIII'IRNUI- III IIIIIIIII-IIII-IIII I'l'fdl'lbllflflflazl IIIIIIIIIIII-IIII-I I‘ll-fllilflllikillIl III-IIIIIII-IIII IIIIIJPfIJWCvlihmII II-II-l Iiilh’ujfilk SIB... III-III. IIIIIIIIIIVIIII IIII!II-II%IIIII III ’g-III l I III-III.- III-IIII-IIIIIIIIIIIIII-IIII-I7All-IIIIIIIIIIIIIII III-III...III-Il-IIIIIIII-IIF'(III-IIIIIIIIIIIIIIII III-I!IIIIII---'-E:::----l-IIIIIIIIIIIIIIll-III...- ---::—-u-------I----III-II...-III-IIIIII‘IIIIIIIIII III-IIIIIIIII-IIII-IIII-III..-III-IIIIIIIIIIIIII-II III-III..-IIIIIIIIIIII-II-IIIIIIIIIIIIIIIIIIIIIIIII III-IIIIIIIIIIIIII.-III-IIII-IIIIIIIIIIIIIIIIIII-II. IIIIII-IIIIII-III..-III-II-IIIIIIIIIII-IIII-IIIIIIa III-II—IIIIIIIIIII-IIIII-IIIIIIIIIIIIIIIIII-III..- l0 hajjao t2~f+fifizkfio 13 $0 90 loo Below, circle one of the items separated by / in each set. From the curve, H's bp is original mixture was about at least / at most 84°, and the 55/60/65/70/75/85%L. 5. (2) 6. (3) 7. (3) 8. (2) 9 (2) _ 2 - Acetic Acid (AA), CH3COOH, has strong H-bonding in the liquid. (1) It has abnormally low enthalpy and entropy of vaporiza- tion; and (2) its vapor density corresponds to MW ~ double its formula weight. Correlate (1) and (2) using <15 words. A pure organic liquid containing C, H, and 0 shows strong C—H absorption in the IR, but no other strong absorption above 1550 cm'l. Name or draw two oxygen-containing groups of atoms excluded by this result. An aqueous solution containing 20.0 g isopropyl alcohol (IPA, d = 0.78) is "salted out". The upper layer weighs 16.0 g and is 85% IPA, based on its measured density. Calculate what fraction of the original 20 g IPA is in the upper layer. Compound C, MW = 108, is steam distilled when Pexternal = 760 torr. If P°w(ater) = 600 torr at the mixture's bp, calculate the mass ratio in the distillate; MWwater = 18. W(ater) and odorous cpd D are mixed. Two liquid phases exist at equilibriu -—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 ' -3- 10.(4)(a)(2) A Drying Agent forms only a 2-hydrate; the DA/DA 2W has rel humidity = 5.0%. For a 3—fold DA excess added to a 3 g W per L Org Solv saturated soln, calculate the final W conc. (b)(2) For the solution above treated with a DA of capacity 0.20 9 W per g DA, calculate how much DA is needed to dry 600 mL W—satd OS. For this calcn, assume all the W is removed. 11. (6) For cpd F, KVB/VA, (i.e., z) 6. Calculate the fraction of F unextracted [PUB = 1/(1 + (z/n))n] for (a) use of B all at once, and (b) use of B so FUE is minimized. Take e3 = 20. (a)(2) (b)(2) (c)(2) For 2 > 6, the superiority of (b) to (a) (circle one choice)-- gets even better. stays the same. decreases. 12. (2) J has mp = 100°, and L has mp = 130°. The most probable mp for a mixture of 85% J and 15% L is (circle one answer)—— 95° 98° 105° 115° 125° 135° 13. (3) 14. (6) (a)(2) (b)(2) (C) (2) 15. (3) -4- A certain sample x, of mp = 75—80°, is suspected to be either largely cpd M or largely cpd N (but could contain neither). A mixture melting point with pure M of mp = 82—83° is 68-69°; a mmp with pure N of mp = 90—91° is 79-82°. Tell what these data say about the likely composition of X; give reasoning. A solid sample comprises 10 g P and 5.0 g Q, whose solubili- ties in a solvent S are independent. The solubility of each in not S is 5.0 g per 100 g S. In cold S, P's solubility is 1.0 g per 100 g S; Q is four times as soluble. Calculate the minimum amount of S needed to keep all the Q in solution after cooling. Show calculation. Remembering that it is desirable to get the entire sample dissolved, calculate how much hot S one should use initially. If the initial dissolution in hot S gives a colorless solution with some brown goo sticking to the flask walls, tell what one should do next. Use <10 words. Glucose (dextrose, grape sugar) has mp ~148°. Addition of 1 g water to 6 g glucose depresses its mp to 95°. Restate these data in solubility terms; refer to a temperature, the nature of the solution (dilute, conc, saturated), and to solution composition in terms of the mass ratio of glucose to water. -5- 16.(10) Recall the preparation of n-BuI: acetone g-BuBr + NaI ——————> n—BuI + NaBr MW = 137 FW = 150 MW = 184 d = 1.27 d = 1.61 (a)(5) Suppose one starts with 5.48 g n-BuBr and 7.5 g NaI. Calcu- late what volume (in mL) of n-BuI corresponds to a 75% yield. (b)(5) Both t-Bu-Cl and n—Bu-Br react rapidly with NaI in ethanol, giving ~100% yields of NaCl and NaBr respectively. Explain the following in mechanistic terms, using <35 words total: (1) The rxn rate of t—BuCl is independent of [I'], while that of n—BuBr does depend on [I'], and (2) the yield of n-Bu-I is unchanged by even a high conc of t—BuCl in the same rxn soln. 17. (6) Note the data below: W £13m (1) n-Bu-Br -——-> n-Bu+ + Br" + 178 (2) NaI -—--> Na+ + I" + 164 (3) n—Bu+ + I‘ —--—> n-Bu—I - 171 (4) Na+ + Br' -—--> NaBr — 174.5 (5) NaCl —-—-> Na+ + c1' + 183 (6) n—Bu—Cl -—-—> Q-Bu+ + c1' + 185 N (a)(3) Calculate (XGoverall for the reaction: n—Bu—Cl + NaI —--—> g—Bu-I + NaCl, showing your calculation. (b)(3) Given that Keq for the reaction of (a) above is highly favora- ble, tell why alkyl chlorides are worthless in a practical sense for making alkyl iodides by the process used in this lab. You need not do calculations but do refer to how 5 changes along the reaction path. ...
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This note was uploaded on 10/06/2009 for the course CHEM 322A taught by Professor Singer during the Spring '08 term at USC.

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