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doc20101005115830 - CH 341 Physical Chemistry Test 1 Fall...

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Unformatted text preview: CH 341, Physical Chemistry Test 1 Fall 2008} Constants: R = 8.314 or 0.08206 you know the units. g = 9.80665 m 3'2 Name 1 atm= 1.0135x105 Pa 1bar=1x105 Pa Part 1: Answer 4 of the foliowing 5 questions. If you answer more than 4 cross out the one you wish not to be graded. Otherwise only the first 4 will be graded. 9 points each. k1 kg 1. F or the reaction mechanism A —> B —> C can you always use the steady—state approximation, or if not, what must be true? I t2.<< EL 2. Thermal conductivity can be expressed as a iinear flux-force relationship: Jq=wt<$ where K is the thermal conductivity. A thermopane window is constructed fi'orn two sheets of glass with a narrow spacing. Calculate the thermal flux in a thermopane window with a spacing of 2.00 mm between the panes of glass. Assume the Outside air temperature is 00°C and the inside is 200°C. The thermal conductivity is 0.0252 J nt‘] K"E s‘E at 15°C and 1 atm. Assume a i elm-fin t linear temperature gradient. 0. a ‘ - an "r r» --_'J 3. Calculate the pressure inside your mouth that would be necessary to drink aysoft drink through a straw of length 20.0 cm. Assume the drink has the density of water at 200°C, 0.9982 g IIIL'I and the atmospheric pressure is 1.000 bar. t. "i- f Pia '2 @0116? will i also 6? P ~ Jr 0 ‘31ng ml .c-e “ " , W] 7501 PI or}; (1133:1170?) ‘7: !\J 4. A substance with a molar absorption coefficient of 12,144. M“1 cm1 and a concentration of 2.33x10"S M is found in a lake. Calculate the fraction of the light incident at the surface of the lake that remains at :Cdeptlf? of 1.00 In. 0330 f E (a ' M25113C " M \l 0 Je ’53 D ~I *M leenrmglaeewe he) JfiJ‘) “3 _ _. 2 at?) C l1}— ;Hill M roam ' ‘13:: C 3 _ 0“ A 5’ 5.316; 5,3 '1 6,3546 : chgX/m’ _ ‘ CW l L) . 5. A photovoltaic panel can convert at best 12% of the light flux into DC electrical power. The conversion of the DC power from a solar panel to AC power that can be used to power appliances or to feed into the power grid is about'77% efficient. The yearly average insolation for Boston is 4.16 kWh in'2 day'l. Calculate the AC power available per square meter from photovoltaic cells operating at 12% efficiency in Boston. Express your results in joules per 1%” ’ second and also watts. [Hint l kWh = 3.6){106 J] vh‘biflflmfi . : . ». 7 ‘ I v) A 2"? \2 fl __J \ Il Amt; with gamut 9—, :' WWW/(2 2—4. (%\ 7:5? it i’lnLC'Gi'l ’7‘?" day. “L “3) "2 "VL fl," hafs :r r 4‘)- R ’ . I ' jg AC. 1%“ng ;- #721231 (0.11.) ((3.77) , [6'5 51 1‘ mo F ha: “"35; hi"- Part2: Answer 4 of the following 6 questions. If you answer more than 4 cross out the ones you wish not to‘be graded. Otherwise only the first 4 will be graded. 16 points each. ‘ l. {/94 3:23, lfjlf‘ 6. The rate constant for the decomposipon of a certain substance is 2.80x10'3 L mol‘I s‘1 at 3dO°C and 1.3 8):]0'2 L niol‘l s'1 at 50.0°C. Calculate the activation energy and pre-exponential factor. ) ) \_ p, /(.er>><)0 ..a,_ jar; arm—— “J H e“*--——"". l f“ I? 5 303‘ C” J» ( ’3 gas. (v girl K l a r” A a, K {.5469 1 ,QQ‘Héa/O k) E“ 51““:le Q ; «Qt/ta re “5463 T: a e 7. The following mechanism has been proposed for an enzyme reaction with two substrates, A and B: M A EA 2 lat [5ij -- la“; DEA] — lag. TEL/13 E15340. (i) k: 4 «r ._- tn EA+BE2>EAB+Y ’3 L31 LEAH/Bl" iz'slli’znfl ’6 D k ,1 r ___t EAB 3> E + P j; E»; 0—“) where EA and EAB are enzyme gorge-ate complexes. Assuming that kg and k3 are large compared to lg, show that the mechanism gives the rate law: d[P] _k1 1C2|EHA||BI dt _ k_1+i{g[B] A it'll M- ' I ' I“? l L "‘ w K -_. 4 5550.6 :1. “i‘Ci’x or. b ii gewi'i i2; l 8. Find the integrated rate law for a third~order reaction with stoichiometry A —> B and rate law — d[A]/dt = k3 [A]3. (Give the linearized form, for example for a second order reaction the linear form of the integrated rate law is 1/[A] — l/[A]O = kgt) ! A. w 2 3 7:5) t : (.1 l a A r‘ ‘1 t i i“ i W 71% "1 i i i ,1- e " 7/: fl [/1] \j _g @Uiifg ~ l: 4—. 'x. k_/ , 4" last +6 i ': of 7172 of 217i M... 9. The cis—Irans isomeration of 1-ethyl~2~methylcyclopropane is first order in the forward and reverse directions: _ kl) . W C” “r “’0’” W ' k] The reaction, starting with only as isomer has the time course given in the table, above. The tong-time value for the CiS—isomer concentration is 000443 M. Determine (k1 + 1L1). in F‘ {ii} Ha it): 0‘ 01677 M \‘Er‘t‘la’wivq 2‘ ‘ .a' a \ -\ ‘ rm Metal (ms) {000 3 ” {El—“67? " (510m LE7 Kiliaiiz‘flq) ;‘ EJE‘QK Sfi' 10. Consider a reaction with the stoichiometry: A + B -> C + D. Assume that both A and B absorb at a specific wavelength, while C and D do not. Assume also that A is the limiting reagent, [A]D < [BL]. Remember that the concentration of A is determined by the extent of the reaction: [A] t [AL—é. Assume that the absorbance of the mixture is the sum of the absorbances: A = EAI’ [A] + SE? [B], where 8A and 813 are the molar extinction coefficients of A and B, respectively. Show that: El _ [MOLE _ A—Am [ALF . — ADM-Ac) ~ . . ..\ f5: 9 51.20%. Eggs] ’1 gig C mil?) J” may i~~ alter {rem gear; [ID—so 4 1 2 11. Solve the matrix equation (I 0. = [I] for x and y. —1 [HI t_(1\31]l M12) _ M22 —M12] ] m. M21M22 _ IMI —M21 M11 w) was; I» ml. 1* «~I , r ,. Of” "1 ‘ #2 H (oafifilfi (4)0) 23 /_ ./C> m or ...
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This note was uploaded on 10/06/2010 for the course ES ES271 taught by Professor Machaut during the Spring '10 term at Colby.

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doc20101005115830 - CH 341 Physical Chemistry Test 1 Fall...

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