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Test 1 Key - Page 0 SR The University of Arizona Chem. 152...

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Unformatted text preview: Page 0 SR The University of Arizona Chem. 152 Summer 2009 Andrew J. Grall, PhD EXAM N0. 1 THE FOLLOWTNG MUST BE COMPLETELY FELLEB-EN OR YOUR EXAM WELL NOT BE GRADED. - NAME: PRINT (clearly) THERE-IS A 3 -POINT_ PENALTY F R ILLEGIBLE NAMES or improper Scantron information; ' DIRECTIONS: eDO NOT OPEN THE EXAM UNTIL IN STRUCTED TO DO SO. GYOU MUST USE PENCILS ON THE SCANTRONS eON YOUR SCANTRON — WRITE AND BUBBLE IN YOUR STUDENT ID STARTING ON THE LEFT — FOR THE ‘S’ AT THE BEGINNING, BUBBLE IN A ZERO CON YOUR SCANTRON -— WRIT E AND BUBBLE IN YOUR LAST AND FIRST NAMES SEPARATED BY A SPACE fiFILL IN THE CORRESPONDING FORM LETTER~A or B oKEEP ALL PAPERS IN FRONT OF YOU, ON YOUR DESK AT ALL TIMES. OCROSS OUT ANY SCRAP WORK THAT YOU DO NOT WANT INCLUDED IN YOUR ANSWERS. OFOR MULTIPLE CHOICE QUESTIONS, BUBBLE IN THE LETTER ON- YOUR SCANTRON OF THE CHOICE THAT BEST ANSWERS THE QUESTION. UNLESS NOTED THERE IS ONLY ONE CORRECT CHOICE. IF MORE THAN ONE CHOICE IS SELECTED THE QUESTION WILL BE MARKED WRONG. SELECT THE CLOSEST NUMERICAL ANSWERS IF YOUR CALCULATION IS SLIGHTLY DIFFERENT. GFOR QUESTIONS MARKED “FREE ANSWER” or PARTIAL CREDTT -— INCLUDE ALL YOUR CALCULATIONS. IF YOU GIVE ONLY THE CALCULATED ANSWER, IT WILL BE GRADE!) AS ZERO CREDIT. OPOINT ALLOCATION FOR EACH QUESTION IS INDICATED. OGTVE ANSWERS FOR CALCULATIONS TO THE CORRECT NUMBER OF SIGNIFICANT FIGURES AND INCLUDE UNITS IN THE ANSWER CWT-TEN YOU HAVE FINISHED PUT THE SCANTRON SHEET INSIDE THE BOOKLET BEFORE HANDING IT IN. ' I eHOLD YOUR PICTURE ID UP TO YOUR FACE WHEN TURNING IN AN EXAM eWHEN FINISHED, LAST NAMES BEGINNING A—K, TURN IN YOUR TESTS IN FRONT —— LAST NAMES L~Z, TURN IN YOUR TESTS IN THE BACK My Signature below certifies that I have used a calculator for numerical calcuiations only and that I have not done anything unethical while taking this exam. I have read and understand the directions NAME-- SIGN DO NOT WRITE IN THIS BOX 9) ITS 10) [15 11) Ill} 13) l 10 TOTAL (free answer) TOTAL (scantron) Page i Multinie Choice — Choose the BEST answer ta each question and bnhhle it in en the scantren. Each problem is worth a points. I. What data should be plotted to show that experimental concentration data fits a zero—order reaction? g A) ln[reactant] vs. time B) [reactant] vs. time C) ln(k) vs. If? D) l/[reaetant] vs. time E) ln(k) vs. Ea 2. Dr. Grall performed a kinetic demonstration in class in which he put isopropyl alcohol in a dish and ignited it. He also put isopropyl alcohol in a big water bottle, swished it around and C ignited it. Which factor below can help explain why the 2‘1d reaction occurred at a faster rate? A) Temperature B) Concentration C) Physicai State/Surface Area D) Catalyst 3. Given the following proposed mechanism, predict the rate law for the overall reaction. A2 + QB —> 2AB (overall reaction) 3 E Mechanism k J: J 2 Cflj z: ggiggjg 2 :- fas ~5- ‘w 1+3 ZAB sloiv Fate rag/HE B j r k Waffij l A) Rate = Mann} 3) Rate a k[A2][B] (3) Rate = k[A2}{B]5 1 1)) Rate 2 k[A2] E) Rate = k [A2] 5 {B} 4. A catalyst speeds up a chemical reaction by A) increasing the temperature B) Providing additional reactant C C) Decreasing Ea D) Changing the reaction from endothermic, to exothermic 5. Given the following balanced equation, determine the rate of reaction with respect to [$02]. 2 302(g) +02(g) +2303(g) a so, A 1 A" A) Rate = ~—1- [ J B) Rate = +1 [80*] (3) Rate 3 __ A[SOE] 2 At 2 At At 2A[SOZ] At D) Rate = + E a Wmmwmmmmmmmmmmmmmw«WWI-w-wmwmmmlmunmwwmnwwmwwmwwwmmmmwwmmmxmmmn anwmmim-W“Wiwmwmlmuvmfimmmxw<M4llWfiNMl/MMWWWWIVWWWWflmWMMIWWW‘Wmmmmlwwwiw 4? C D Page 2 6. What is the overall order of the foliowing reaction, given the rate law? 2X+3 Y—>ZZ Rate:k[X][Y]2 A) 3rd order B) SEh order C) 2nd order D) lst order E) 0th order 7. What are the units of k in the following rate law? Rate : ng32 A) Ms B) M e s C) M“s"‘ 1)) M? E) les 8. Given the following rate law, how does the rate of reaction change if the concentration of X is doubled? Rate = k [X]3 {Y12 A) The rate of reaction will increase by a factor of 2. B) The rate of reaction will increase by a factor of 4. C) The rate of reaction wiil increase by a factor of 6. D) The rate of reaction will increase by a factor of 8. E) The rate of reaction wiil remain unchanged. Pae3 0' a: E‘ree answer *— Answer the question compietety — Show your world Partial cretlit may be giveri. PUT YGUR ANSWERS EN TEE EQXES WHEN PRESENT. 9. rE‘he foiiowirrg is a mechanism for a reaction: aware 2+A Slow W4- c a are? ac Fast (a) Write the balanced equation for the overall reaction: (3 pts) 475+: gee—73c: (b) Write the overall rate law for the above reaction: (3 pts} (c) Sketch a reaction coordinate diagram (activation energy curve) for the above reaction. The reaction is exothermic. Label activation energies (forward and reverse}, AHa overall reactants, overali groducts, and activated comglexes (*1 on the graph. (9 pts) Rxn progress (d) Draw a dotted line to Show how the addition of a catalyst would affect the above diagram. (3 pts) Page 4 10. The decomposition of HE foliows the equation 2HE(g) flu, 15$? H2(g) + Hg) The rate law expression is rate = k, where k = 1.20 x 10'4 mol/(L 5). 1317.05 minutes after an experiment had begun, the HI concentration was equal to 0.125 moi/L. a.What was the initial concentration of fit in the experiment? (8 pts) 6‘? @6391} “I: —- ( Agaxxsza‘w/gflofia) +559 EH11”: 0,, [#6 M 0 inflow much time (min) would it take for the HI to qecrease to one half of the original amount? (7 PtS) ‘2; ‘ 5‘ $7 _ 9’ a; 0.20%?” ghf/g) 11. A reaction was run at several temperatures and the following graph was constructed: lnk 1/12: (K'I) The equation of the line was y = —25858x + 0.405. What was the activation energy for the reaction in hJ/mol? (10 pt) egsers?: '5 W fifgxeegggéf Page 5 12. Chtorine 0ioxit§e is a reddish—yeliow gas that is soluhie in water. in basic soiution it gives chlorate and chioritc ions: zcaogoq) + zoa‘(aq) a Clogaq) + e10; (aq) + agoo) The following experiments were run and instantaneous rates of C102 were measm‘ea at 20. seconds for each experiment. Initiai concentrations (1111th) {C102,} {0 | Inst. rate 1111th s! (a) 0.060 0.030 0.0248 (b) 0.020 0.030 0.00276 (0) 0.020 0.090 0.00828 a. What is the rate law for the reaction? (9 pts) .owafi/aécamcgj%0¢?9 b. Determine the rate constant, i: (value and units). (3 pts) c. What is the reaction order? (3 pts) 3 13. Which of the following compounds would be slowest in an 3N2 reaction with OK? Give a one sentence explanation. (10 pts) CH20H3 . wwwmmmummwmuw...“. : MMMM.MMMAwwmmmmummammwwmm wwwmawas‘m miWWmmwmmmmmWWWmwimage-amoum.WWWHWWWHMWWMMM n A AAAmpMMnmhquWMWMWWWVAWWWWWWWWWMWW“““VWNW"'""‘m‘ww Page 6 Periodic Table :38 .43 4:53 :63 173 : BB :23 @321 §4A 55A 610 E70 gsA ‘ 5H6 g $1.008 ; , . . . . __ _. _. .9. _. $5.1 gee 3 7c gN :0 ‘F §Ne 359419.012; g1001§12.01;14.0 = 6.00§19.00;20.1s§ E11 ":12 1 $13 $141 €15 21'3" . a 1 : s - 2 ; s é :3 gNa gMgg gAl gs: 3E3 15% gAr 522.99 :2431 326.90 123.09 §30.9 .07 235.45 339.95 ,, €2.32“ {2.4 .§.2.7.,.§2.é gig, . . .3). §Ca gSc :‘E'i 1v §Cr Mn iFe 5C0 iNi ECU: :Zn 363 §Ge 3A5 e ‘gfir iKr § 3 1K . §39.10 i40.03244.96§47.33§50.94$52.00 154.94 g55.35§58.93158.69563.55E65.39 9.72 72.613749 7896099038360; in §Sr gv §2r greb 1690 5% $1211 gm: gpd §Ag ica gin $51: $13 §Te :1 32m . 385.47 §s7.62 £03.91 391.22 192.91 $5.94 3(93) 1101.1 §102.9 $105.4 3107.9 3112.4 ;114.3 3118.7 121331216 5126.9 ;131.3 76 77 70 {79 80 E01 82 $33 E84 585 86 3 05 Ir Pt gAu Hg {TI EPb §Bi §Po gAt gang 190.2 ,192.2 195.1 g197.0 200.6 3204.4 §207.2 309.0 ;(209) g(210) 3(222) - ‘111 112 i (277) 3 F I57; .72... 7.3, 36 gas 13a 11a gm Ta iw gRe r 7132.9 2137.3 1138.9 178.5 4180.9 Q1839 9.86.2 E f $57... .iééwéid‘} €1.05... .Ei.dj....§mé , 1,169 mg. 1? 3Fr sRa 3A: W Db ESg gBh iHs {Mt ’ ‘ 10.23). §E?§-9..._???:P ,i..(%§1.2_..9§2.2.. if???) £52,523. 3955.) {(256) $9. (272) [A10 - 1n [AL =—kt haif-life = M E nations: A =-kt+ A half»§ife= q [ it [ 10 2k [A10 k - 1 \- —m1——=kt+ 1 half-life: 1 ; 111g "Ea [A]. [AL] MAID k1 R T2 T1 ink = —Ea/R(1/T) + lnA R = 8.3145 J/mol K TK = Tc + 273.15 E k : Ae"(~Ea/RT) . ...
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Test 1 Key - Page 0 SR The University of Arizona Chem. 152...

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