Sample_Exam_Question - 83 02 up 295 on.o no 8 =5.2 so a 2.u 38 an 295 oz.0 32 oo 33 9w:6 a 2.n no RED.9 $3.0328 2.a 326 02 no 035 2 6>63 02

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Unformatted text preview: 83:. 02 up: 295» on... .o no... 8. =5 .2... so: a: 2:. .u . 38%.. an? 295» oz .0 32 oo. 33 9w. :6: a: 2:. .n no RED. .9. $3 .0328 2:. .a 326 02 no; 035» 2:. 6 >63 02 up: 39% 55 on... .n no: on. 33 2282.52 .23.... of. d :9: 3. no; 23.2352 55.8 of. .n :9: co. an? ER 26: o: 2:. .n 5283» 05.2 .588 2:03 .35 .o 2.0: .o . . . 29:3 9.: 5 8:23 5538 .92. 22> 82:. .u :9: 02 mm? 22 >6: o: 2:. .0 so. 02 was 95.23an :96 .28.? 2:. .n no... 8. 33 52353 .3838 2:. d . _ 55583 :88 8:8 m 98888.0 Sandmsg an: 2.2 36:30 8." Hog . 83203215.. EB. .535 «535 3 Skin 2 553963. 33.36 So .ncozmcflnxo 2930a j< .0. 95:2 smtnohnm 2.: 225 .32 mm .0: 2m 0 v5 0 .m c. 85me 9.... .co 6%. cm 2 83.60% 2.: vcm 35:58 :03 26; ( Efluo_mEoEo .0. 2.3.9.8 9t .mmcoxi 2.2.52 no.5 .o 233:. m co 2.5. 00 .50. .0 336a» Em 263m .cozmoac 5mm 2 335cm 69:8 .13 20.3 2 23 am 60:33 20mm c_ 32.3 no .3... .3323 one :2... 20:52.: E mQOIo mJAFJDE 0:... Eu coma 25 co 30:32... on... .< 538g mfiufeoEamE :V 3955:: EmEo. 8 03¢me Am 0396:. C .2303 30305 gm: 2:03 30> Emoncmn 35m... .0 EnoEm on. 52.85.28 on. .0 @5568 an. 5 Es be, mm; 22.6me .50» ._ 6 2550mm. 2 Entnzfiwm :mgfooocnz .563. .932 0. azouoozm. .028... .o 2.2 m5 3 =3, .23 .1046 .o “29.. 3: new 108.... .o 22.. 0.. 5.; 3%.... E. w n 3x :26 .0 «3203. m_ E39233 5;; £009.... .553. E223. .233. 2 3.0.8:... .38.. .o 2.2 o... B a; .2; join 8 2o... 3 new 1000;. .o 29.. 0.. 5.; 95.2. Ba . u 3v. :26 3 u umv. .8202... 3.8% ms. .0 mcozmbcmucou m5 .0 3:2 E 38: Emficoo 52.9.53 2: .2 5.3298 9: m>_o Am 3 0.: + "10.00:. 11M. 10.10 + :08... .. “.5200 .565 mm Emancmn 323E .0 33.593 ms. 50 Emu o. 8203 so» 0335 ._ mzofimm: Ecxw m_ 58 - EN E36 I. i ou and your lap partner (A. Einstein) have done the simple/fractional distillation experiment with methanol and water. At the 12 mL point your temperature reading was 782" and Albert's was 694". Which distillation procedure did you perform (simple or fractional)? Give a brief reason for your answer. 2. What is the purpose of the reflux apparatus used in the esterification experiment (other than to impress your non-chemical friends with a complex apparatus)? 3. Aspirin can be recrystallized from acetone where it is soluble to the extent of 17.0 g per 100 mL at 20°C. it 43 grams of impure aspirin are dissolved in 80 mL of hot acetone and the solution is then slowly cooled to 20‘0, what is the maximum amount of aspirin that would be expected to crystallize from the solution? 4. What volume of 2.5M sodium hydroxide is required to convert 6.1 g of benzoic acid (MW: 122 glmol) entirely into its sodium salt? (Give your answer in mL). 5. Compound 2 (SP. 120°C) was to be isolated from an aqueous reaction mixture by an extraction using one of the tollowing solvents. The partition (distribution) coefficient and boiling point of the solvents are also included: Solvent K m ' Bolling palm: "at" of solvent A 0.55 53°C 5 1.5 42‘C C 15 117°C 0 13 ’ 65°C Which selvent would be the best choice for this separation. Explain your rejection of the other three solvents. 6. Give m reasons for the use of sulfuric acid in the esterification experiment. 6. The solubility of acetanilide in hot water is 5.0 gl100mL at 100°C and in cold water is 0.53 9/100 mL at 0°C. Assume a linear relationship between solubility and temperature. What would be the maximum theoretical percent recovery if 459 of acetanilide were recrystallized from 80 mL of boiling water and cooled to 25°C before filtering. A I~J THis Prweuom wHicH DUN—L lZe‘Qutme‘ (OOPS! :t: MADE Au mrLorz. V00 W mAtLé‘ Au ASSUMP'nop Arsour m.- Pucgbullt’ 1D A/LrLtUb’ Armh‘ COUL‘EU“ Afifiwm- 566 IF you emu SPOT me- PMI5LCM 3) A . mmtzglen‘e‘otgsngxxe ts mode by combining 50.0 g of acetone and 50.03 of I“ 27] m." d I , e vapor pressure: of pure Acetone 1nd pure methanol , m 43 torr, respectively. Assume ldeel solution and gas beh‘ViOY- The molecular ' h “d 310 5/ mole rmtfivgfiz B 0’ “mm “a “mm” m 53-1 s/mole A. Determine the mole fraction of acetone in the solution. ’3, Determine the partial pressure of acetone in the vapor state at 25°C Question 14 refers to the following table. 14. a) If you were going to pack your own column for fractional distillation, which m of column packing would give you the best separation? a. old mbber bands . b. petrified wood chips c. crushed kidney stones d. shredded wheat cereal b) From the data above, which of these particular columns would give the best separation ? ‘ a. old rubber bands b. petrified wood chips c. crushed kidney stones d. shredded wheat cereal 7. Given below is the boiling point-composition diagram for hexane/ethyl ether mixtures at 760 mm pressure. Using this diagram answer the following questions: a) What is the initial boiling point of a mixture that is 30 mote% hexane? b) What is the mole% of ether in the vapor above the boiling mixture in (a)? c) What is the initial temperature of the vapor as it condenses on the thermo- meter in a simple distillation setup? ——-— . .. . 2a E'tl'i‘filifx'a’fi’fm‘e.i."7.".‘ E=§EE!-.i To: poratt rc ('t) immf. -...._. M='—‘l I ..-_ _... ..-.. .-... ' ‘ -Z. - ___T a .__,,., a, , _ - t , |_‘ 1ft) Mole ’t Hexane 10 ,..._.3 u .-....'.:.- a MolgtEtEe': 352.». if .9na-exguiizaaatxérc §§3§3§i%§.§3§£3> .>_ Ill .2: . oil-d Egan-83311385383731... ESE-83:95.36 0.98:838‘3vlfigd Egglgfullid tizgiigalilazog a II 93:35.. 9.8.2.31... §§Z§§£.I§ia ggliéogtgiid ginning-83.....- . 3353i;- ‘ix’i-oiggggzog .0 £235.. £58... gin-vista .35 .9335. 833.... {lbs .I zgsglss‘iocsiiozfsz .o .2.- 3a....- 622-395.! Biiglgligoogufgii Ooolitzgltid ingoggcaogizd 323-912;:13588.‘ 352°- :QSN-I—ibo. In! 2... .n [1" .n can)... oil—0‘ .D 60944 Igfiugg£!:§3§0.8§s3§§£ .< .35.» 9.53 cc. 3:38;... 2: 2: :25. .3556 . ‘ 53:253. 05 .6 33» 3.23% 2: 35.0 5.3 9:23 9a 55 355 320:... 2: 8:85 £355.: on .2023..- 5 B. :2me 2: :3 9.- 5:9: nu 5»EoE.;£.~5 x:- 0231 .xnnc 2: E uEEBp 51:8» .2: Eu. 35:3... or: E...( .5305 no 955 vozwccésfi E: 326:8 in“: 52.3 252 ~=§$E§£ .o nunomEou 3.223. x23. 2: 35.5.92. TC laboratory Clyoe Einstein {no relation) carried out the tollowing Grignard syntheSIs in the 251 CH] e . ' . other H ‘ Mam CHOCHC WCHZB' . M9 ——‘ H20 , Product ‘ 9 gm; . 5 0 ms 0 9 gms 3.4 gm: = two: 151 At. M = 24 MW = 34 MW [(3 a) Draw the main product of this reaction. D) Calculate the maximum theoretical yield of product tor this reaction tn gms‘ C-es::or~.s 1 1-13 retet to the followmg TLC experiment which was carried out on the 'zna’ procuct of a reaction whim used 1,2-diphenylethanol to make a substance called trans-strlpene The TLC was eluted with a solvent made from 90% hexane and 10% ethyl acetate. as the solvent 0 '0» V‘ I 3 0 g rrans-stitbene 2 '5 3 ~ m :- student‘s product = a 3 3 9 a 1.2-dlphenylethanot 3 Fr ‘3 '- oIventiront E ° ° §§g 9 9 59. F, 8 ‘3 u g o z E 3 5 What is the (approximate) R! value of the 1,2-diphenylethanot7 I ff g 9 [a g .. : 3 i _ z 83 E r ' o 12 From these results. one can conclude that the students product 0 0 ° ‘ 3 3’ is lairly pure trens—stilbene contains no trens-stilbene is a mixture 0! trens-stilbene and starting material is neither trene~stitbene nor 1.2-diphenylethanol trawoo or porinbar ere (atom/6 0:: 13 To increase the Rt value oi the 1.2-diphenyl ethanol one could cut-’3 umth Sir or Aratotdwoo (atom/6 a use a more polar elution solvent 5 use e less polar elution solvent 3 use 9 larger amount oi materiel when spotting the plate 5) let the solvent elute ott the top of the plate 13 14 15 16 17 Which ol the lollowmg methods wOuld be most uselul lor separating asotio Substance that has preCIpitaled in an aqueous solution? (-5 simple distillation ol the water Item the solid tractional distillation of the water Item the sohd G steam drstillation ot the water and the solid , G) extraction of the solid with an organic solvent ( e uction filtration of the mixture Non»polar substances are more likely to dissolve in ’f non-polar solvents a polar solvents (u, a box of corn flakes ('3) make up your own wrong answer here Dunng a recrystallization, optimal purity will be obtained by letting the initially saturated solution cool slowly @ rapidly chilling the solution in an ice bath bring the solution to a boil very slowly refluxing the solution belore cooling it dawn Slmp|e distillation separates compounds based on a differences in molecular weight ‘9 ditlerences in vapor pressure a dillerences in solubility G; diflerences in extractability An ester, isoamyl propionate (bp, 160') IS to be separated trom a reaction mixture by extraction at room temperature (25°C). Which of the lollowtng water-insoluble ethers w0uld be the best solvent to use lor the extraction? 6 methyl ethyl ether (op, 10‘C) (-1 isopropyl ether (bp, 68'C) G isoamyl ether (bp, 172'C) @ allot the above choices would be equally good ...
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This note was uploaded on 02/25/2009 for the course CHEM 2510 taught by Professor Russo,s during the Fall '07 term at Cornell University (Engineering School).

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Sample_Exam_Question - 83 02 up 295 on.o no 8 =5.2 so a 2.u 38 an 295 oz.0 32 oo 33 9w:6 a 2.n no RED.9 $3.0328 2.a 326 02 no 035 2 6>63 02

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