2000solutions

2000solutions - GIVEN NAME(S STUDENT NUMBER w wm pm THE...

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Unformatted text preview: GIVEN NAME(S): STUDENT NUMBER: w wm pm; THE UNIVERSITY OF BRITISH COLUMBIA FINAL EXAMINATION, APRIL 2000 Lecturer: CW (Physical Chemistry) SIGNATURE: Dr. NE. Burlinson Z-/.4l77. 7; 7 SURNAME: (PRINT, CAPITALS) l:30P THIS EXAMINATION CONSISTS OF ll NUMBERED PAGES . PLEASE CHECK THAT YOU HAVE A COMPLETE EXAMINATION PAPER Attempt ALL Nine (9} questions. All work must be shown In this booklet. Time: 2.5 Heurs Use or l‘nnr: \ «nu. Catcuramus is war PERMITI’HD RULES? VERNINGEXAMINATI NS 1. EACH CANDIDATE SHOULD BE PREPARED TO PRODUCE. UPON REQUEST. HIS’HER LIBRARYIAMS CARD. 2. READ AND OBSERVE THE FOLLOWING RULES: No candidate shall be permitted to enter the examination room after the expiration of one-halt“ hour: or to leave during the first half-hour ofthc examination. Candidates are net permitted to ask questions ofthe invigilators, except in cases ot'supposcd errors 0r ambiguities in examination questions. CAUTION - Candidates guilty of any of the following, or similar. dishonest practices shall be immediater dismissed from the examination and shall be liable to disciplinary action. (a) Making use of any books: papers or memoranda, other than those authorized by the examiners. (1:) Speaking or communicating with other candidates. (e) Purposely exposing written papers to the view of other candidates. The plea of accident or forgetfitlncss shall not be received. CHEMISTRY 205 - Final Examination. April 2000 INFORMATION GIVEN: p. = 3.3 :4 JK-imol-1: 0.0010 Lalm K"mol" M = "’0' L“ 102:0.093 lLalm.=IOI.3J K = 0°C + 273 F - 96.500 c mo!" SOME FAMILIAR EQUATIONS: m conditions to which they apply am NOT specified hm. J 1 211-I_I Tq' n_l =(n-1)kn1; [1/2 = —T_l whcrcn=2, 3... 028 l 2 (P+—)(V-nb)= nRT PV=—nN mfi 2 . V a AE=AH—A(PV) 053— AG°=-RT Ianq _ AH u: = "ms-an as: nCv lnT—Z-HIR [mg mg = - W" (i-L) n VI p. R T1 12 - ‘5 (RT AC=VAP-SAT AH=q,=J'nC.dT k=Ae 3 See" I 30cc" - .0315?an at 298 K AG =— IIFE = Wu“ 1" . . I” 1 v '1 - _ A” .. ST-So-ST- InfiKs)—+ f + nCp(|)g+ V + Intptg)? o Tr Tf TV TV l. The following kinetic data were obtained for the decomposition of ammonia on a heated tungsten surface at 200°C. Initial Press(mmI-Ig): 65 105 150 185 Half-lifdsec) : 290 469 670 826 Show how you would determine the order of the reaction and the rate constant. £73 nocturner vita» [talc-fads: 1‘»: a .'. Malay. <1 +v1xcr¢ar¢l¢v u. ~cl/thkt” auktyg —... or ‘é = 31. 1-. a 7!?!" a a W h 'lz __'_// k = a 5- : o ttz 1(2‘10) kinetic ordcr = o k a z 0: “g 1 ., a“) -= 0~HRM5ec' it is Constant .7. amour-$6». 2. The half-life for the acid catalyzed hydrolysis ofsucrosc to glucose and fructose at 25°C is constant at 500 minutes at a constant pH = 5.0. At the same temperature but at a constant pH = 4.0. the half-life is constant at 50 minutes. Explain briefly how you would deduce what m and it must be in the rate law and calculate the rate constant, k. -d[sucrose]/dt = k [sucrose]"‘[I-N" r- o I". I. ‘ II. .Sitnc: LIP] : Clovis-{uni (45 4 6412421 51') K 33/}? / - . m ‘ ~ 13;.4- 1, .. — disJ/At= is [53 Mt since m= 1 \~:;-- 'éI/z t‘sr Cpns int/It M = l "I. n " I . 7‘- . - — ’* / 0- 15ch fpld (vacuum? I» [liq Age was: s n -t . -J fiy‘z tern fplcl or mctrflzfiaé mice 12'» ffifl k: mfi H MM 46‘! n =1 / 1’: V; = WZzW'd le’ '4 it. {Hi} . -t ‘4 l2 -. ' ' 9‘ 6q3/500miw w 15%.? 3. Given the following mechanism for the thermal decomposition of nilryl chloride, kt N02Cl -> NO; + Cl (slow step) k2 N02Cl + Cl —) N0; + Cl; (fast step) 3.) Write a steady state assumption equation for the chlorine atom concentration: .d[Cl]ldt= o = lz, [Nazca] -kg£vga3£cf3" .‘fi/‘F = l? \-_,.. N (/hz b.) Show that the empirical first order rate constant for the disappearance of N02Cl can be identified with 2k] . - cl {nasal/At = l2, [Asbwa + kZUU03a‘1CCQ-j -_ 121 [003.42.] +— ‘RRDUUDJZ‘J E = 2J9, [M92453 I a. W C Lake-xi SIM sic? accuvs once "i305: mplpc. ~94: 9030?. all; Veto/M71)ng Aug Sabsaéqz-MYL {346+ :42? - A HJfiUpwé-é: 12k, WOW] In the multiple choice questions below, circle the answer(s) that correctly completes the statements (NOTE there maybe more than one correct answer to each statement). a.) The kinetic order ofan elementary step in a mechanism is... _ "/1 _ b . l. . 1. always determined by the stoichiometry ofthe products. i'1’ ’ "‘ ' ' l 1” 2. not necessarily related to the stoichiometry of the reactants. 9 the "molecularity" of the elementary step. .~ i; -. 3‘ 5,554 a necessarily an integer number. / x», . - u ~' .. ,5: l— , 5. possibly fractional. / b.) In Michaelis—Menten enzyme kinetics... Q at low concentrations of substrate the reaction is first order in substrate. 2. at high concentrations of substrate the reaction is first order in substrate Q the k, (or k;) step in the mechanism is unimolecular 4. plots of V vs [S] are linear 5. Lineweaver-Burke plots require more enzyme than in M-M plots for determining K... c.) In a simple P vs T phase diagram... 0) the locus of points that constitute the phase boundary equals dP/d'l‘ 2. the locus of points that constitute the phase boundary equals AH/TAS 3. the phases are not in equilibrium at the triple point 6) the free energy's are the same for the phases at the phase boundary 5. the entropy's are the same for the phases at the phase boundary 5. One mole of a monatomic ideal gas, initially at 300K and 1 mm, is heated to 400K. Calculate q, w, AE, and AH when this change is performed in each of the following I . I a! - ways. , / _ £7 JIM ‘ a.) at constanl volume: n=lmalc T‘s3paK T?=L£DOK Ff!- 141‘!» F1: v: =“RTVF, :p-o?a(3M)K q: “1qu v. c w= o u) so .suhaa AV = 0 55: 12"}? T AE zfn OVA: - 1(%R>lppzzmq- Z = 55 AH: 2.031%)“ q= 29‘” V = 0.0?2X’45‘9K = . x 144.1”: 32 9L. w=-f’3I.TGf 1-4:!“ w = ~ Ext/AV = -t(32.?—2e.¢} AB: WHT 3 “RR Lari-m : -?.2xml.3= 93: 3‘ AH- .203“? I 5. c.) by adiabatic compression; q= 0 .T‘ L? adiaba-h‘c % = a -.-. 3' AE 3‘ AH 5AM: 4.5 45598- w 114+ '. W = AB: AH- 929-7? T S. d.) What is the AS.,, for part 511. and Sb. above? AS= VIC 3” I3 V T.‘ I , - ' -( = I iii—p" ' TX inpartSa.) AS,,,- 3.5? TK ' _ -/ 05 '—' “ark-‘1" ‘ '(%3)&w InpanSb.)as,,,= (7'!)ka 6. The normal boiling point of chloroform (CHC13) is 62°C and its molar heat of vaporization is 42 kJ mol". If one mole of liquid chloroform at 62°C and l atm. pressure is heated and evaporated isothermally and completely against a constant ,j. - ;( external pressure of 1 atm. . Calculate q, w, AE, AH. 68,“ . :35qu , and AG for thc , It”! I " process. ' gr=AttsAH r = Loud” q: WJ ‘0 ' " (aim/z "reel/fies: MET w: #211353 PM: alH‘XLZ-i-R—ZBJ - 'ZHSJ— AB: 511,;3" DE = gm) : ‘12J000‘2'7‘35 m- timer am MW = 3f, as”- [25 9 N" -l ail; AH”; = 42,9929 =125.%TK ASmi= o T‘ 335K a :D ASpr-J - A??? + Assurv 3’56: Vfflzrllflbla (pa/paws mmfluf 2; I . a+ m7va 3.314,: 9&CL141478. ._ “l ASMW ‘ “3251-: TIC = atm-;st = 69 92:32::- §%5‘ 4%“ Péul (5' 11;. into.) A} G— = AH 47:3, I7; 3‘1; 7} 7. a.) Determine the equilibrium constant (KP) at 25°C for the reaction, Br1(g) + C120 (g) :3 Br;0(g) + 02(5) given the following data for the standard enthalpies of formation and the standard third law entropies (all at 25°C). Br; (5) 3'20 C'! (8) 0mm mot") 80.0 76.0 5° (1 K" mol") 231.0 200.0 253.0 175.0 9 ~— 0 9 AH = AH - AH rm 2- 7c?ch Z 1cnmflf- f "M -’ ’. -'."'J:.‘ 5 #4 4’0 = fit/Ll} ca; Jaw-’5’” 05”“ = 2.15;er - 2.5”;st ' _ ,- 6 =— (253+ (1-5) ~L2pp+z31 z 3:06:31? fié‘vxn = “Liam-r 569-7?) =[f 4' L 5 : "‘3’94/5'3HCP-7!) 19,. 3.50 C “— K : 3 . 5-0 ('3 . 7. b.) Indicate the spontaneous direction of this process for a reaction mixture Defined by the partial pressarcs: Br; (05 atm), C110 (I .0 atm), Br30 (5.0 atm) and C]; (10.0 am) Show all calculations. oc=AG°+zzuwa. = -3104, + 3-3z4(27r)£w ‘X’0 0.5"): l : 4:04. +ufiw = +9.39% 5m}: (66%- >0 ream/5a: Viz; 1.5 J P ,__. SFpWSA'M 85344 5. Ha... 8. State the conditions which are necessary for the equations to be TRUE, by clearly checking the appropriate squares: (1) always (2) at constant T (3) at constant T and P 325:: (5) under revetsiblc conditions. (NOTE : there may be more than one necessary condition) (4) for ideal I Alw. T r&- K} Re (3) .... .... .. ... .... .. .. h) as - nR ln(V;/V1) i) AG = tum.“ (whre w“. = electrical 3) AH = q9 b) C, = C.- + R c) q = -w (for PVT changes in gases) d) AS.” + AS”, = 0 e) AS,” = dq,¢...'T f) PN. = PW: g)AG=0 9. The combustion (ic oxidation) of methane to carbon dioxide and water. .. CH4 (3) + 20; (g) -> C0 + 2H20 (l) ...is shown from tables to have a 56°03. -818 kJ. troc mica It is proposed to use methane in an elec 1 fuel cell. With basic electrolyte the half cell reactions are... CH4 (3) + SOH‘ (aq) -> C02 (9) + 6H20 (1) + 8c‘ E°=? 1/202 (g) + H200) + 26-.» 2OH‘(aq) E°= +0.401v a.) Calculate the standard cell voltage fat the Fuel cell a O em: = ’ 48' = “W”? : (wean/wits]. '1' } tie-(6497”)! ’f HMO} b.) Calculate the standard reduction potential of the cot/cm half cell above. o 9 a - a 50:3! ‘ 55x44!» " age/we; ' (Ea/602) 5/ ~ 60 ~Am = fd-fZD/“MM -‘- #04521” 5. - (fie/4(4) 42'de ’ c.) What is the maximum electrical work that oculd be obtained from one mole of methane gas? / .9 e” = 48- "fi/féa/F— pf— wizé/mé/ It ...
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This note was uploaded on 01/31/2012 for the course CHEM 205 taught by Professor Burnell during the Spring '07 term at UBC.

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2000solutions - GIVEN NAME(S STUDENT NUMBER w wm pm THE...

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