key_exam_2_F06

# key_exam_2_F06 - WW 1 ea:55 GRADE 100 a I(15 pts In class...

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Unformatted text preview: WW 1%? ea; :55; GRADE / 100 a % I) (15 pts) In class we found an equation for the AG (mixing) of gases. Starting with the equation V1,- P , AS =~ann «~2— 5 [P1] a @1515 a) (3)ﬁrst change this into an equation with V2 and V}. A4 "l; lb aésanQvLC/WZ): +%@%> v; V??? b) (4)create an equation for the AS (per mole) mixing of two gases A (V A) and 80/3) originally in a container(VT) separated by a barrier. 7561’ 5 :2 +MAR£M girl/g f‘ I Vat: : r3 7”“ legal :4? {Ma _ 74mm}:ng Q) t r ’“A 47255;, “a +74% 7,; (313.3%: m 1%»er (a c) (3 )write down from what you have done a general equation based on the mole fraction of cash gas (Xi)for any number of gases mixing ET, J“ .. [Q S a“)? d) (3) why do gases never separate but always mix under thesegireumstances w _ ><é(l pa <3 61; 55\$ d) (2) Draw a rough graph of AS (mixing) vs. XA from 0 to 1 for just two gases A and B. 35A f 2) (15 pts) The protein lysozyme breaks down bacterial cell walls. This enzyme unfolds slowly from a compact three-dimensional structure to a long, ﬂexible chain at 75.5C with AuaDSH 2 +509 kJ/mol. Assuming the process is reversible. ,t ‘ I I J F- L! 6 jﬂ/ I”; G (79355;; 273‘) We l b) (5) in simple terms explain why the value for the system only is reasonable. Positive, negative, large, small? why? a. (gees W MW Pesx?”{‘ew<s [email protected] 52:3 564’ V5“) 74M (5!” use“ 4W3“: W7 WM“ (be! M a a aura/WM)“ pig/3.3— l. as ME? 17) 3) (15 pts) Near absolute zero Debye estimates that Cp = aT3. a) (10 pts) With this information develop an equation for AS near absolute zero and integrate your equation from 0 to 1K. {3w :3] CL: 5 ﬁle IEQ sag TWET so, as Se 0T T 5 O T © (2) Wm M S : lag/Pas ,0» b) (5pts) Roughly in your own words using Boltmnannj‘sj approach suggest why the entropy changes so rapidly near absolute zero. N “a”? am” )7 0 ,IL 22\$ Tlé-Eéié: a as (/g% ram} AWﬁMCﬁLCE’W? Fm Woe/£94 7327;, h g gimp \$90,0ng Cea%3 “Tit; ﬁst/37W? Whites-r» ~25 ska-Lam M stream Twat/e" D0 # 4 0R 5. Put only ONE answer below— WWW? ‘Pﬂfaﬁ/ )7 60 1’ {7 [1 N9"? 5.; ; 4) (15 points) We have said that measuring S is difﬁcult in the laboratory. Using K, a which can ﬂag; be measured with relative ease and a Maxwell relationship show that for any substance "E _ i I as ii [m] = "q" Where a: = and K ___£_ E] OR 6V T If V 6T P V 6P T 5) (15 points) Remembering the fundamental equations for dU and dH ( see table) L6; " ‘1“: 72K ”" PA “a lode-{o @ % £17)?" "2‘ . I g”; .1. .7“. ‘ R; if, T‘ ’ij} \ CHM/J “We: 0 ) .M r r. H/ has“; ,5 n"? , h n *2; ~ © C V “E T Lb r © if ) time t i i. / \ © a? (7% t j J (W i?) v Q“ a? )1) a; , w 1 z ’ \ . i =4“ ‘ V 6) (10 points) For the stretching of an ideal rubber hand using force F over distance L , the exact differential is dU = TdS - FdL a) (5 pts) What is [6 U/BL]S ? = @ b) (Spts) Create a Maxwell—like relationship ﬁorn the expression for dU 7) (15 points) For centuries it was thought that molecules from living things could only be made by living systems passing on the essence of life Urea is a waste product of mammals. Using your skills, compute if the reaction of two very inorganic materials ammonia and carbon dioxide could react directly to make urea. Is the process product favored (spontaneous) at 25C? Explain with numbers (not just yes/no) 2NH3 +C02 ——> mchNHZ +H20 (g) C? a) (5)Show ifspontaneous using AG at 298 b 6% a 61'; g «2% «828881 mgeé~ré 9e”) ’56?! ‘5‘ a @- ” #1”. ‘ a» a raw/9”" 9879.8, .» (“4272) s. 4%,; \$55») a f ‘8 b) (10)Whether or not spontaneous at 298C ﬁnd the tempera the systerajs just in equilibrium See tables bé _~. A A!» w «fa 5a .7— ___, if) S gages; [jggg’wgzﬂgj w [ZCsﬁﬁéiQr-éf z M . ... 58¢.S + 4357 75mm wag—a, WW jail? yum‘ian m naval-1:“ Wm. A aﬁaﬂaﬁ; {- :aaz.) “(3265923 423% l 330?. Z W“ “if; '- w ' f * I 5t: 0 cmpd AHrO AGfO 31° ,i ‘ C02 (g) ~393.5kJ/mole -394.4k.l/mole 213.4J/moleK *““‘“‘"WW W ' co (g) -110 437 198 H20(g) -241.8 -228.6 188.8 N0(g) 90.25 86.55 210 C0N2H4 (s)[urea] -3 45 445 102 NH3 -46.1 46.45 192 H2 0 o 130 8) (15 pts) Explain how you would ﬁnd AG for the reaction A —> B at constant pressure under the following conditions. a 6:? a) (5 pts) The reaction takes place at 298K {3‘ i a ﬁg” bé’e 594%) viz a [Ca 512825,") fagég b) (5 pts) The reaction takes place at 198K and we assume AH and Ag are constant over this range . ‘ a} W 59\$???) r. 828\$qu (P5123 .. 695/) g, (R: of») km wiggle" c) (5 pts) The reaction takes place at 75K and we assume AH and AS are not constant over this range. (7 T" A! «:5 5 3%? "7" a; .: d7 , Am, 4;, {55/271567 W3 5'WFS ‘1‘ C W73 ? Fm \$46"; £69”) 79337” J” '_______...A .2; . NH j “7‘ - 5M: «neswcz P 6.23).: T ggsgx/ ...
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## This test prep was uploaded on 04/03/2008 for the course CHEM 480A taught by Professor Wesolowski during the Fall '07 term at Arizona.

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key_exam_2_F06 - WW 1 ea:55 GRADE 100 a I(15 pts In class...

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