PS1_Sol_Rev_2 - “I Chem 215 Fall 2007 i’roblem Set 1...

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Unformatted text preview: “I. Chem. 215, Fall 2007 i’roblem Set 1 Due Fri. Aug. 31, 2:00 I’M Name: SOLO”?! t3 NJ 3 Lab TA Name: Lab Day: 1. When aiuminum is ignited in bromine, aiuminum bromide is formed. In a certain experiment, 6.0 g of akuminum reacted with an excess of bromine to yieid 50.3 g of aiumimlm bromide. Caicuiate the theoreticak and percent yiekd of aiuminum bromide. Z/q/ + 33/72.” ——~—:> Z fl/grj. ”901%.? A/ 32% z 0-ZZZMO/M zcfimf {no/e; AIR/‘33 [91199956955 = O, 222. {QSYVM:L47 /00% fie/0’). 2 3mm 53 mag. m (azzawwflzcm W} .3. 5’" +2 ) I", , ' 77W fist/fizz: $9.27 (W 537, v‘v we 9/9: “Zaflzelole flxmafle 85%, Sily 2. Consider a 5.430 gram mixture of FeO and F8304. This mixture reacts complezely with an excess of oxygen to form 5.??9 g of F6203. Caiculate the percenz by mass F60 in {he originai mixmre. Pewvé’ons are. 25:; 0 ‘1‘” $03” W F5232? .9! ‘J‘FaO +— 0;; “921-72210; Q) 2Fa30, + 2502, «$9.103 96 91:8309 +' 02.5“"? éFe-‘z,03© 48-7“): ‘~'= 7m”? Fe0[mw= 53:951. law 2 71.95%”) ,1 5,9363% 5 7/0n5536y [mod r: 3/5285) «FM/409% 23/.559fim9] a a 5,7733 3 577‘}; g *2, Wales R103 PF Janet} fiKrgyg+3{M¢£7%M /5"?.70%r/ 3,6/7x/f9 I X Erma Men/9.5 Fez Q3 fp/mg/s E Wu“! EwiD nuksFe rmflmfi= " %%*x a X," 2% F 2' aBASS‘VuI + 5.1222 n» 3.4/9x/0“2'u I .ZIxH‘v'l? m M): . 2(713'5) §( 2.31. 5'9 > 5“ 0/ gm uMI‘HWXLWar/é - W em: max-r7303 =301.97 are 2:06 ‘73 fir/wflg38, [‘2 2 3. The total mass that can be lifted by a balloon is given by the difference between the mass of air displaced by the balloon and the mass of gas inside the balloon. Consider a hoteair balloon that approximates a sphere 5.00 meters in diameter, and eoniains air heated to 65°C. The sartourrding air temperature is 2EDC. The pressure in the oaiioon is eqaai to the atmospheric pressure, 745 "Torr. a) Neglecting the mass of the walls of the balloon, what {oral mass can file balloon lift? You can assume an average molar mass of dry air, based on 78% N2, 21% 02, 1% Ar, neglecring trace gases. aw. MW 5am: (0.7?)(290) (Olmyszofiéw/X‘mo): 29,034,? V== go?» §w(2,50n)3m éSJ-l m3 3 n: 31 . 1—7344”) ( “er/0 4’) 2.... was”. RT (0,0306%? ‘7’” T“) s + 2 QC. ‘ n a”, 7’8’3XIO & 4€7 bias A I .(Z‘t‘HK), mid WM” 2 "‘ A033S‘Lmlu " (95°C (338': F) HM. r. "2.251:- 20. 5.. r 23 x! m «if t y‘ . ‘ .- am IH a 3%moles) (figs/”Q z: Loam 31 ==~ 10.0 1:3 b) If the balloon was insteaé 13 ed with enough 2 gas at 2l°C an 745 Torr to achieve e same volume as in part a), what total mass can the balloon iifi? moles a; M; 3/1 loalloon % ZES'? 5713550? Hz 3A 56 ”Jon 3(2097molcx) (245m film-F “—7- 5: 3C 9 lug; A?“ air 6‘3sflaeed ‘(ECWMt/fll)/29'0 9/4/ * 7‘Wk7 Ll¥+ a? “Z. Ellen's: 7Ll‘W-l-JZ3LS‘: 7lthc7 o) What mass could the hot air balloon in a) lift in Denver, CO, where the pressure is {ypioally 630 Torr? A‘l” ZIOC) Q3073rr) nae” "‘ £23 (2‘57 ”1,3- " 795 n 3' L733 23” a, J‘ M ( ,., ,) a 630 , ) :2» £9. £1 3.51: m 795 (“m b7) 3 4. Draw Lewis dot structures for each of the foliowing moiecules. inciude important: resonance forms and formal} charges if appropriate. The first atom is the ccntrai atom in each case. 4' F" 0" a) NC13 N: Se bl'N'Cl €01:3{7é)==»2:e 24g“ :6): Gig Z” ‘04 2;” 2' r- : : ‘ b) 304 3 G36 69 ‘ O ‘ ‘ C) CEOZ cl 3 7; ‘5 Jo ‘ 20 . 2(5)» :26” 3Q, IQ; «Pam’- mama; " 9‘ 9 3 lo 4 Q @ GVI¥A zfly‘ffl‘fill‘fl a c- a ‘ , " ‘ ” l O; .OIfOC'oOr'H ‘P:¢C/n0.é-~):0jc/:oc 'a o I a , ’ t x , ; : ’ +g-er (viaduct: ‘ mu. lam}: Aw! ’11—“ , J‘ I 1 cm x3; 8: F 3/: 4F; qué'zazgé" u ...Xe‘;‘. 3L; ’1 ’ ’ Ft 4 Liquid hydrazine (N284) is used as a fuel in rockets. Either gaseous oxygen (02) or iiquid dinitrogen tetroxide (N204) can be used as the oxidizing agent. The products are nitrogen gas anti gaseous water. a) Write baianced equations for the two reactions. flat/9(2) "’" Oztei”“”’ 2.95” 2 ”40(9) C? b) A common approach for estimating enthalpy m” “'6 New 3‘3”" “”9“ mm” changes in reactions empioys the concept of - Sins“? Bonds Writes Bends average bond dissociation energies, D, the Kiwi-l 433- NM?! 39} 1H 149 Gee? 6'54 . . . ' Hm? 565 N~«N 160 ENG 208 {25:16 859 quantity of energy required to break one Hung; m- N“? m HS; 125 0.430- 495 ‘ ' . [-II—M'Br 3613 N--— CI 2.00 CWO‘ Kit-'5 nio‘ie of covelent bonds m a gaseous speczes. Hui 293 Nd! 243 SW” :34? {32—30 mg: Usmg Hess Law, we calcniate the enthaipy N-MO 2m 34»; '32? NmG so? ' ’ (Iwi‘i 433 0m“ 46"? SwC! .253 MEN 42'8 change for any reaction by eubtracting the ewe 347 owe 145 S—wfir ,2??? .. . Nag 9.45%. totai energy of bonds formed m the products emu 305 owe! 1.9a sws _gsa -. Crag .625- , C.—~O 35$ OM43 ”263 -' ' 'CE. ' 8.91 from the totai energy of bonds broken m the {3 \\\\\ F 435 M 234 59533. . m - - reactants: C—CI . 339 .9in 'I ' 393-1 _ C.—Br 2733 Mr m Same - m; on: 24:1; _Fmoi £53 same-.4522; __-_._' Mime D(bonds broken} memes formed) -c;:—_s- _ .3259 __ “gig; g; (Elm-Br. 213 ' 65538 the bond energies given, caiculate the ”Mi" ‘93 enthaipy change (in k3) for the combustion of 1 moie of liquid N2H4 using each of the oxidants, gaseous 02 or iiquid N204. The heat of “(IL—x0 {(102} = ?99 vaporization of N2H4 is 45 kflmoi, anti that for N204 is 30 kJ/moi. d ‘ I ___. 1V~ IlJ Wag/c. ‘MI “w - ‘w t a Lewis Sy/uwéapes ; 2 A, 2(56)“ [05: [/f : J A“ 4” \ 2; 9 Q 2%“ I c /9’ 9" , /‘/ , a. 2 u 2/593’05 nah/.A/ ' 2 0-0 4/0 4/43/15...» . 395' :0 ' C C). For Aéfl? (‘3) +0349) ““9 ”2.69)?“ 2 ”£0693 CD Mg-‘pmol)p¢0k 7/4,”) 4 qua/(3WUAPJ) 7‘ ’ma/{qqff%4i) F 4/ ~— /m//?9/%- qu/vc7¢%g) == "590/? 3' 9f" 2 #‘I(e)~—9A/# Age +9513“ “éfiixwozm” ”Lafiwmm Afle 490%)“- Far 2%” - \ — H7) +1140 9 “‘934/ (9) #64505.) AfleémuX/Lowmafi 9Mdé9IWmJ)f/M*{//(0£37 ,g: 2 Am +2. 202 “3m0f(q9/£%J)“ 3mM/VL7U/mdzi 42%!!!" % ’/) Fr 2 ,u g I. (9)» 21/ ll Ail: + 9010'}, F r ZMLH w L! o»; H 3U..La)+‘-/# 1/2049!» my}?! ..... 362w . @157 ....... fbH: esagfutfiéofiwmwlzrgg For 2. Moles; Hzihiéfl Mia-- lZlSkU-j P£n©5 For I moleoF MzHuge) M2: west? 2:) One possibic criierion for choosing between the {wo oxiéants IS the eniiiaipy change per gram of oxidant for combosiion of 1 mole of hydrazine. Based on this, which oxiéam IS a better choice? '93" €MOfl®15H3“5HSk-y :9!" 2203 a? Ogfllmh.) For 02) [5H Paramm 03;. omean‘i'“ "%Tfi [7,033. For @491:sz ® mm: wees/:3” Sr 4/603 0? N;Dy(¢:§mi¢) For “LG“ 5449“?” ogaxidanfm %- /32k 3T 0 5' MP clinic /7; [or . 4/ Ad 2 5 A cf 7 Em“ flyc Aflflygfl) d) Assuming no heat losses, and that the entire enthaipy of reaction resuits in heaiing of {he gases, caiculaze {he finai temperature of the gases produced upon combustion for each oxidanz, assuming an initiai temperature of 0°C. The molar heat capacities of nitrogen gas and water vapor are 20.8 If“ C moi and 33.6 WC moi, respectiveiy. For Mudb, imlo. My? Zonal 195441 0 gm Prod»: MCW°‘J"J= Oreo-{”20 8%)4—2mf 339—) a fig 0% AHA 5950‘»ch CSI'" .%#- 59SK/033', éHaK 38071: 7}: $61937- 2'73: 626$ K For Qx® 3mb‘65 Uz.+ qwé! 292.0 me. pfldvce/ Cg’z 8% fire W... (9/79/07..- acegvK. e) Caicoiate the voiumc of gas prodoceci per g! gfiro lfit (fuci + oxidant) each case. Assume a nozzle pressure of 10 atm. Ifiiiis is the criterion useci {0 choose the oxidant, which would you seiect? For-(D not me Fondue; "j 3 male: a? gas «J- éfigK‘W; 1044," a “0'33” (3 cmaesYo 0320s Egg mm) I00 :- ‘1594 "“95 9VGWEZq%:rS} AV?" 95219411; Rr® W Mark? 7W"!!! 0? 543 EH17K1>VI WWOflikfibvag 3’73... £237! .. o ., J mess {39*ch 13“) 3° 02’ 33955 2"” £23m )WM Neo‘l WM 2373/3. So 0;. «W M _ 1') In tight of the fact that tungsten has the highest melting point (3 695 K) of any metal, do the temperatures caicuiated in part (2) seem reasonabie? In no more than three sentences, explain why your caieuiations might be in error. Na, WWW M bias“; +00 M, Sigma/ma. 6 W cgms: CD gm WSIWJwflWmh WWfi/rgfl “TM, ~30 rust 651:1de «PK a m ' and ® Wag V490 pmdmfi‘vkafl' 44%..“ 6. Nitrogen dig: is pri y res nSIbie%£fg'gtge aze seegomfl§2€7fifiiniefiggggng N204 when cooled. Suppose you put I52 g of pure NO; in a 10.0 L flask at 25000. You then (500% it to ZSGC and measure the total pressure to be 0.500 aim. What partial} pressures and mole fractions of N02 and N204 are present? Hint: aiways write a baiaue-ed equation, in this case N02 is the reactant. 2M02_(qt “a ”2.0qu mates M0; =1 .1233 =- 5330 (of 250%) Hebe/W9 +5 ........ ' ' ' \ “3:0 i ©3?£2)£+\; :- Lgowd-fi‘é) 3(0‘500‘7‘4”) ((0.0EIOCM’SCZ‘33KD '""" o t :Oa'ZQ’wmfikS “3,0 0,330“ .. 020% ) 5rfnoles U07)“ 0330~1(m 30.078 fleet,» 0’3):+m PM,” ates-41m ...
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