02 S16 (1PM) Exam 1 SOLUTIONS.pdf - Exam 1(1 PM Class Form...

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Unformatted text preview: Exam 1 (1 PM Class) Form A April 22, 2016 Before doing anything, fill in the following on your ParSCORE form: 1) Write your name 2) Bubble in FORM A 3) Bubble in your PERM number (7 digits only—no extra numbers) Instructions: No hats or hoods allowed. No books or notes allowed. No sharing of calculators. Cell phones, iPods, headsets/headphones, and any other electronic devices must be turned off and put away. There are a total of 6 pages (17 questions) on the exam. Not every question is worth the same number of points—-point values are indicated for each question. You may work out the problems and write your answers on this exam; however, you must completely fill in the appropriate bubblels) on your ParSCORE form. When you are finished, turn in the ParSCORE form ONLY. You may keep your exam. The answers to the exam will be posted on our course web page. Questions 1—2. Consider the following information: You have been given two samples, each containing one mole of Ne gas. Sample A is heated from 300°C to 400°C at constant volume. Sample B is heated from 300°C to 400°C at constant pressure. g _ r r? Hodc'. Cf; ilzi CV' ESQ- 1. (5 pts) Based on the information above, the change in enthalpy of sample A is less than the change in internal energy forsampleB- Sample Al A4: I’lCP 0")“ lgov am? fatal gas flocefs a) True SQMP\¢ E OF: {)CVD'T *FDY flfl’) [dead 66") \pi/oCeSS. ial Sample A: OH=ZO7GIS 1 Shoe: 2070: 7|ZVl’3, SWMPM El 35: l2“??? sample A 7 Sample \3. 2. (5 pts) Based on the information above, the work for the process involving Sample A is greater than the work for the process involving Sample B. Sample 14'. Cowstar‘l’ UD\MM€' Avtol 5;) u-zo @ Samgie El Veal gas a+ Carola"): P gas gxgands b) False _ a. _ M‘— wMem hem-ltd. SD L.)< 0, (wow; {3 Negativc\. 0 SO uovk (ow A \S 7 Wow: Lav \s. O 7 0| mega hvz :li . 3. (5 pts) Which of the following substances is expected to have the largest standard molar entropy (8°) at 298K? a) C02(gl - gases l/lcuzc [Aral/xiv WWW», HAW. b) He (g) Eat-5% (£1 M V 0') N204 (B) W ' QMJVOP/ li/LC‘x/Jerasflt‘s as Camp/ZXMLL7 QL MO\€ CLA‘C [Act/£34363. make— l M°\¢ of €ML§¥6UACZ 90M H.)- Clem/ta": l/l +M¢C¢ Shanda/d ,fio/MS‘ 4. (5 pts) Which of the following is a properly written formation reaction? 2 0H’ is inc—\— am elZMw-l’. Ca2+(aq) + 2 OH'(aq) -—-> Ca(OH)2(s) , . fiSZBM + 3 F2 (g) ---> ZBF3 (g) —§ 69¢ ééi'Ci’en‘l' (13v Weduck mus)? \e-c \, X” ngl + Cllg) ---> HCllg) ~—7> H 4,44 Cl avg noi— standa/d elamwtal Fla/ms d) more tha onenftheseisaproper 'tten formation reaction 0L he, Alogen and Chloyine, e) none of these is a properly written formation reaction 3m=\ gas ———3 0 Mol 3‘“ 5. (5 pts) Predict the Sign of AS forthe following reaction: 2 H2 (g) + 02 (g) ---> 2 H20 (I) Ioo‘C a—l— (MDLCS o—C 3&5 C) AS=° mil Ago/edge 6. (5 pts) Predict the value of K for a reaction with a negative value of AG". ' {I 5004 OI 4km reachoin is span-tamacus a) K<1 | . x b) K=1 detv S—Hmol qu Condnd'i'ms. ‘l’ln S ”(ans 0' n (IT-3:51-») {Waves +0 y,'? [44— (F/Dflluc'lt {QUE/30‘) a PKOdIAC’F d) K<0 \ Cat/meal I xw Will have \fi > . I o . _ -06 ET. ‘ Cam also Flue] CWV7 nejah‘w DC; Vale“ MW” {:6 , K Lei“ be. >\ 7. (5 pts) Complete the following statement: In an reaction, the reactants contain stronger bonds thanthe products. new ““5 n¢¢d \éSS emcrjw Mud» +D bv¢4\¢ VVoducf- LOAA" ) E th ' emu” ? a xo ermic bbvak Yeaclvanlr Z— (CAL-kayfi ‘90de av: firs/170’. bands _ (\LL 40t¢5 fluavc encrev 'l'D burned; M) +145 .-5 am and- Hui/Wm “hm ( x w pm 3v as S ' 8. (6 pts) Consider the following process: A (I) —-—> A (g) AE = 24.3 kJ/mol When one mole of liquid A is vaporized at a constant pressure, 3.5 k] of work is performed. Calculate AH for the condensation of one mole of gaseous A. . , L3 a) -20.8kJ o UOPOWZOK‘HOV‘ ’ AC?) *3 fl (’9 DE, 2‘1. 3 (Mal b’ ‘24“ I: pvoduccd/ 5° ML __ kJ gas “<0. Lao/l4: foam: ~37SLT DH: OE + ACRE ————_°°“*"*P—> fill: OE—r va if ’ PM: '22,: W Imam ?/3\/:..+a,sl=:.). DH; ZMIBLa—e 3.?L‘3:Z,7.T§L3 1CD, Vapoviia’n’kbn . J I H. a Co/ldemsah'om'. Affifl—e ,éwj) {ML/5+ +dl¢e neéahéffifi :5” 24,35} O pa’Stle O’C €45.04 1%ch nggah‘w. o€ DH and 53 L 9. (6 pts) For NH3, AHfusion— - 5 65 kJ/mol and ASfusion = 28. 9 J mol'1 K'l. Will NH3 [email protected] —25°C? a) yes £0" (vegan/ma DH’ 'S—‘ 6? L? _ AS”: —ZS-7%\.L -06; ©l4’7/33 a £3 [30: (—s “9— M33, (ZWKX 7—8 ichlm-S 00; I325; A670 {134* Span‘l‘anacus. mo\ 10. (6 pts) Consider the following reaction: 2 N20s (g) —-—> 4 N02 (g) + 02 (g) Determine AG° for this reaction at 25°C, given the following thermodynamic information: Substance AH°f (kJ/mol) S" (J mol'1 K4) 239.9 204.8 Aldo: gj OH? (PVOAWCLQ , ngHD; (readrmls\ _ 0,. L 135k. 34 _, wiggling) + wag) — zwmgi a) 98.7 k] e) 324kJ , ~w_ “MK 7 [>50 3 fit} so (f/DA‘A—CLS) gl- 5 (/cch‘l’Ctml’S) J L453. 8 is; ll , a o oz m — (mums Ho " > [0003 06:— DH” 7/380 __ . ".m—v—n—w—m—W __,_,_,,___,.._.. [>60 : ,25,z El! )‘Gnem’ole‘of’an’ideal-gaseXp nds isothermally and reversibly at 0°C as the pressure decreases from 100 atm t01.00 atm. Calculate work W 77 y . , , - v: ma“ a) a)105kJ wwflmfléfl PM M P V Vi Z1 b) 225 k] V : (1,. c -1°’5 Id i P / T'C‘d'. V_____...._.._._.._--P_.. .,......, _ ‘. w... m...“ e) —225 kl “(13.3.1 Met, , , Q? «L Jr" ' 9 fl “Eff. ‘3 L‘JVQV: __, n Bil A J; A 7; Pi ET m t \ l 5 a $5 ml— l , (w) (8 3w mm)(17?>b)jm 100 LAW: leLiSEiS : 405% \ / W.___—vv O L/{Mgl-pjas _..9 3ml 6&5 Q5 4 O Mala: :55 at»: dcclé‘m 12 (6 pts) Consider the following reaction and corresponding thermodynamic information. so2 (g) + 3 co (g) ———> 2co2 (g) + cos (g) AG°=—246 kJ at 298K Which of the following statements is true: a) The reaction is spontaneous at all temperatures b) The reaction is nonspontaneous at all temperatures c) The reaction is spontaneous at 298K, but will become nonspontaneous as temperature is lowered d) The reaction is nonspontaneous at 298K, but will become spontaneous if temperature is lowered ’fiDS“ 46”“ IS @ g;w a-l' V‘jb‘ +eMeSj 'l’l/IIS 46”“ 94"“ LZCOM/Lc. [flrfifl 906 emous ‘4 “A!“ A0- u: ll be Conn—r. 69 13. l6 ptsl Calculate the AH° forthe reaction CZH4 (g) + 6F2 (g) ——-> 2CF4 (g) + 4HF(g) non spgwl—AHCOUJ Given the following reactions and their standard enthalpies: air “gal/t ‘ T, Y 2’ ‘9 H2(g) + F2 (g) ---> 2 HF(g) AH°=—537 k] X 7— ’5 C(S) + 2 leg) -—-> CF11 (g) AH°=—68O kJ revevm ”‘9 2C(s) + 2 H2 (g) ———> C2H4(g) AH°=52.3 kJ . —2382kJ C2 1"”! ”T” K + 2% —~ 3"? .3 \oj C) —4634 kJ L l: v d) —5708kJ N 4 l 1 ‘T’ ZCQA ZV<'(980 la: 3—1165” 9% + 29 .3 I/IHI: z><( 3'37 L3) W‘<v—.:::._ 5 r,— ‘::: .2 C2 MM 4 QB a chfl qHF (04° »ZM8<¢ '47 3M.— 14. (7 pts) Consider the following reaction: HF (aq) F‘ H+ (aq) + F‘ (aq) AG° = 17.9 k) at 298K Predict the direction this reaction will shift at 298K if [HF] = 0.80 M, [H+] = 2.3x10‘3 M, [F] = 0.012 M a) The reaction will shift left Ifl 0 fl S—l—amdav'pf C 3 , 6 M A (9 b) The reaction will not shift c) ereaction willshift rig [3 (D: $60 + £7 EA & 7 “.28 Mal ”In. 15. (7 pts) At a constant pressure of 1 atm, a 23.2 gra sample of water vapor is cooled from 142°C to its boiling point of 100°C and then completely condensed. 'v ’ .' IS the change in entropy A5 for this process? The heat of vaporization of water is 40.7 kJ/mol and CP of water vapor = 36.2 J K'1 mol'l. a) 1361/K (D (410 ( 9') __3 H-LO (a?) A51: N C? £4 if b) 141 J/K c) —4.9J/K M21 / ‘4’ 333 ‘ fl ‘4 H. K 3.0:? K— AS it (llfimsl) (39,”3 2";— 17324735: e _ LBS.” ”L14” j/tm ENE, 32'}? L d1; AS‘L " “ (1.28mi) (Lia-7+ ”AIMS S ngmzi ”WM 0 2-- w 0 No Tc: _ Nojhc WAS ch:lj 16. (7 pts) Consider the following reaction: 3 02 (g) g 2 03 (g) AH° = 285 kJ At 500K, the equilibrium constant (K) for this reaction is 8.3x10‘7. At what temperature will K = 1? KL “ DH“ ( i- \ B ) 415K W “3 "" r'" _ __ Z) 2130K Ki l7— “ "T‘ _‘> c) 0.0241K d) 1150K K”"“""‘” ______ 3r-.- . 1 628K ([1: 3 3X10 “Tl : SOOL | K2 ’v \ TI 1 7 , " V «a E}: K; ‘ J. l l 1 ..__ “"5":= await ::i«' e H | 7/ T] D H" ,__, l .L ,— Lfi,‘ ”(g g‘ Mo" fit) ZA 8’3XZDT} V K- .__.__. .1 M (—3 Moi ( B7 L /‘— : O OO( 5? —5 NOTE There Isone more question on the last pageI ’2 17. (7 pts) Into a coffee cup calorimeter, 5.00 grams of MgO (40.3 g/mol) is added to enough water to produce 105 grams of solution. The following reaction occurs: MgO (s) + H20 (l) ——-> Mg(OH)2 (aq) Initially, the temperature of the MgO and water is 223°C. After the reaction goes to completion, the final temperature of the resulting solution is 323°C. Calculate AH for this reaction in units of kJ/mol MgO. The specific heat capacity of the solution is 4.18 J g'1 °C'1. Ci [054' : l 6‘ 0.) aiv¢0\ a) —37.5 kJ/molMgO ' b) ”37313755! MgO gyym : / q 50 \V‘ c) —4.65 kJ/molMgO d) 886 kJ/molMgO f] 21>“pr : /MSO\V\ C500. b7 s~>\n *3 e) —93.0 kJ/mol MgO I o n 'l a- AL‘VKl/i: Msoln CS \ C3335 \ fl Umi'XE QVC L3— 3“) demo Nil/145v ”Laid” L): Mal M70 , ale.’ M70 line; /l/lo(65 of M90 m +ln‘yc’93v13 fl " Ol’lww / (losfiflmg fi><32fi<~ 223°C S300 9 M520 Imol M90 L40. 39 @ ”W 3 , ’57 Li a g s , Tig‘gfg'k3 mo\ M90 (1 point) Make sure you bubble in your perm and test form on your parscore. You will earn one point for bubbling your correct perm number and exam form. ...
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