01 W16 (3PM) Exam 2 SOLUTIONS.pdf - Exam 2 Chem 13(3PM Form...

Info icon This preview shows pages 1–7. Sign up to view the full content.

Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 2
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 4
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Exam 2 ——Chem 13 (3PM) Form B February 29, 2016 Before doing anything, fill in the following on your ParSCORE form: 1) Write your name 2) Bubble in FORM B 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 7 pages (18 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 bubble(s) 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. 1. (5 pts) The light absorbed for the n=2 to n=4 transition in the H atom will have —wavelength than the light absorbed for the n=2 to n=4 transition in He . 22 (3E; v2.18X/0 "‘7 7?“ ’>/’ 'EPMwi ,7 lfixlo'WB .3: , 1:) fl( {rm ’37 b) shorter c) thesame 1&0“ HI Zfil ,' év He, 2:2. 41% ualw’ QC > Is MVWVJ“: PWPQ'HOV‘“ *0 Z1, 3,:ch 2 IS S/Ma/lu F‘DV H, 0' /0m7zy l/JéIL/elemgl/L of {.-7L+ L49“ .5; aLmyLui. 2. (5 pts) A reaction is believed to occur according to the following mechanism: 2 NO : N392. fast NEGA‘F H2 ---> M + H20 slow 1956+ H2 = N2 + H20 fast/ figs! mic law 4” m wow H ' W‘ What are the units of the rate constant (k) for thwall reactio >/’ Guava” r><v~5 2Mo+ zLQSQ M + 7/qu a M‘S/2 5‘1 b)) M454 [yr—lernncalzglzc, Mic) L I M1 Q 3) Ms—l V6Ul¢ l4“ .- (ale 2 \CLCULOLBC H13 - 5 NF2 _ él'vVlrr'm44< [/1 (2V fl/‘zd’ 614"} (VON Va‘i’c lag". 7. flow. {Kr /: L CUOU1:]C(.C)\] 01.3.9 CU'Lo-Lx: ”:4 17M ""1 “*6" \CL(EL£‘—i°l)fmj .2 m2: LCuojLCHJB k/I m 01,; Lind Ufl'll) 0‘ Vale, Lam _g+6u~{' '- /-"“”““\\\ M a. M L} M,— {I i. \‘\ : k(,\/0 (NO—s) 3:)(0/0 3 M25 ’D/ C’“ W15 \ 3. (5 pts) Rank Cd, H2, and Cu+ in order of increasing reducing strength. E°=0.52V . 5C 0_ lflC‘fea \n E —O.16V lye/«Mk E° = 0.00 v 5 v “to 0"} E°=—0.40v 0 ' 4 £14 E°=—2.23V 0‘? 3) Cd < Cu+< H2 bl in" < ild < H2 d) H2<Cd<Cu+ e) Cd<H2<Cu+ Questions 4-5: Consider the energy diagram shown below for the reaction A ---> B q 9"; . "° "’ /§W reaction progress 4. (5 pts) A catalyst is added that acts only on the second step} of this reaction’s mechanism. What effect will this catal st have on the overall rate of the reaction A ——-> B? y Carl—4L1)? ‘DW‘VS Ea 0‘: 01/il‘7 516,» Z: Vowauav, (Mala datevVM/flfsz S+éft SD Chaflj’hj £4 a; Sizr 7 le no—l' 0((ec-l' Hm: Ouai/d(( rats .£ an. Theov-. Slew Z [‘5 n-cl- ll/v— SloweS‘ 8) b) The overall rate of reaction will not chan-e c) The overall rate of reaction will decrease 5. (5 pts) Based on the energy diagram above, the reaction A --> B is .z" 7/” ‘ fl) Endothermicfl/ b) Exothermic c) Neither exothermic nor endothermic d) Both exothermic and endothermic 6. (5 pts) Fill in the blank: To increase the de Broglie wavelength of an object, one must its velocity. \ l: a) increase / : b the de Broglie wavelength will not change if velocity is changed NV ' c) decrease /\ 1‘5 } f1 uewéélv‘ Fl/DPOVJ'VD Hal +0 U 50 +0 ”/15wa >/ 7. (5 pts) You have been given a Galvanic cell: one half-cell consists of an Fe (5) electrode immersed in a 1.0 M solution of Fe“. The substances used in the other half—cell are unknown. When an NaN03 salt bridge connects the two half— cells, N03" ions from the salt bridge flow into the half—cell containing Fe2+ and Fe (5). Which are more likely to the substancesusedintheunknownhalf-cell? A/WOV‘S «Cram €nl" LV‘JJ‘ flow 4'0 ail/1051K So Fe ’5 and/2e4- Ni2+ + 2e" -—-> Ni (5) E°=—0.25V / 14 Fe2+ + 2e‘ --—> Fe(s) E°=—0.44V PC ‘7 1:: 424' 40AM») an+ + 2e" ---> Zn (5) E°=—0.76V aniom< ,(Iqud Mai/c ‘l’o EALAmC—C a) A Ni 5 electrode immersed in 3.19 M solution of NE" D l7 ° 5' h V‘ C hall 7 e l0 I; dqtcgd w b) A Zn (5) electrode immersed in a 1.0 M solution of an+ F e, is ox ‘ d "2‘4 +° 6' Cal—l lg— CalVAt/u'c, g9 (40% hévé +0 Cl/IOOSK a .— 7.4 Verge/hon ll/ml will QOMIDMQ W214» F24 [72 47“ +72 fr 4L£ All-z— /)cn (zducvlwma hall; PWVldz a PD$\'+"V‘ cell Pu—lew‘h'a I. “11/1/“I‘r Fe ,3 125‘ +2¢‘ .l <3.qu Mr“ 42; a Mr 49'1“! “can >0 . (Dali/mug 8. (5 pts) Determine the balanced reaction described by the line notation: Pthr2+,Cr3+| |C02+| Co 3) Pt + 2 Co2+ ---> Cr2+ + Cr3+ + Co b) 2 Cr2+ + Co -—-> C0 + 2 Cr3+ c) Pt + Cr2+ + Cr3+ --—> Co2+ + Co e) 2Cr2+ + Co2+ -—-> 203* + Co I l/édL/tC’th/i '. 2—0 9. (5 pts) For the reaction A ---> Products, a plot of [A] vs. time yields a straight line if the reaction is < a) ZeroordeE) $2M OldC’V " CA3 C “(C/5 -—l CA0? b) First order . \I—l MES 41 L c) Secondorder COMP‘" +0 , K1 C d) All ofthese e) None of these 10. (6 pts) Determine K for the following reaction at 25°C: HgZCIZ (s) : ng2+ (aq) + 2 Cl‘ (aq) Using the following standard reduction potentials: ((IW" +3 Cl2(g) + 2e —> 2Cl (aq) E°=1.36V F‘” ”‘71 '9Hg22+(aq)+2e —> 2Hg(|) E°=0.789V 0w rial/W ngCl2(s )+2e —> 2Hg(l)+2‘cr(aq) E°=0.271V Note: You may not need to use all of the reduction potentials provided here. -VMU“ 9M» Val! VYMS. +° 76F Hm. jive». vxw. a . X b) 4.5x10‘41 - . ZCI' , c) 1.4x10’36 ”716“ ‘4’ 2C a 2H7 CC) + a Z7l V d) 9.0x10‘36 1.. ‘ I u e) 7.2x1035 Z” 3 (’2) .4 H71 47‘ m.“ M - I 1 H6107. . ’4’ LlfizH-é zcr Cu“ O 3m“ a ' ET ”FEE“ 2““ ><%HSS C «05%) ECéll' fight-H C 6 71—- Mm°lé>< “WW ” (rewfikygzagb) , K/ 45’ p Q ~ V /3></o { 11. (6 pts) Calculate the total energy of 3.1 moles of orange photons (X = 550 nm) ———’J ’3“ it a) 7.03x101 Era MW _ kc :{é 626x10 IQOwi-o 5; b) 2.18x105J ) fi—W —— 3 (alX(O'H c) 1.12x10‘181 SS’OA-n ——-——— d . '41 rm e) 6.74x105 ‘Jle-‘S H Jrln< 6446037 ofi oflc Fl/Lo‘l'OVl, #0 final awerj7 12. (6 pts) The kinetics of the following reaction are studied: A + B --> Products The following data were collected: What will be the initial rate if [A] = 1.9 M and [B]: 2.1 M? ( a f, . ‘* M an K . a) 15-4 M/5 6 ”A “HY Confirm” l' ' Pl 7 I v. A 4-H to 7 b) 2.31M/s (M? %: l4 (O-S§y—(Z."l)l a (5: M43”? ,__ 2.01 fir; (035)1(74‘431. M new QWCMF ra'h'm/ls' F 7. 5 .L—— l- ‘1’ 33 3’ 2,0) M; (/1614) (2.: M) 13. (6 pts) Consider the following second order reaction: A --> Products _+ I/L ’_ —i—-’—— S Q l: CAO) It takes 241 seconds for the concentration ofA to decrease to 25% of its initial value. What is the half life for this reaction? J _ .L ,L CA3 7 he + ('40-) if CAD} ~— lC/‘k '4' CA'JS "—3 a 121 s C V , . . V b)) 4825 (/03 54" SolU A Q. L‘n" L ov (Au-B , [4' JOZSM L M44746 . C) 605 i l quj .4 J...— 3 855 ‘3 C903 l4 ( > (403 —D 2703 t k (201(5) ——3 fly; 723 s L: g \ h ” CAD“) (2mg) 17 U? I 14+» 1.1L e—Lua evt l / 4r , #____. (z, 3 _ 2 3 : Z/L’ils : CS (Tfl>§(z“”)> £1 3 zuis 3 14. (6 pts) A certain first-order reaction has an activation energy of 85 kJ/mol. At a temperature of 84°C, the rate constant (k) is 97 5'1. At what temperature (in degrees Celsius) will the rate constant equal 9700 5'1? : ‘11:" —r,: 304% : 33’? L a) 81°C '5 , Cl 4 4 b) 35°C ’L’ 71305 ”‘2’— . '2 - E} J, - 1 L4;— mgflk‘” ib(’t, 133/5 2&k\:,L,_L A e) 425°C Eu 1" T: ’ 4&5; 1’ (2%”5 35/7” ‘/ 1- g I v ‘C '/ T4, 1 .L '7'» : rum an 4 ._l._ >. Esooo “A,“ $57!, J, 17”, 0.00235 l1, .1) TLC _L——— goons-i : le'fl” 3/1‘321 15. (6 pts) The energy required to remove electrons from the surface of a metal is 222 kJ/mol. Calculate the maximum kinetic energy of an electron ejected from this metal when it is exposed to light with a wavelength of 304 nm. a) 3.69x10‘19i {Eaiwrmi Er ’ El. ——9 P , , 134x1029 Clielcckvowv b; , Eb _) d) 2.22 x 1051 e) 1.02 x 10—181 K Ccltc‘h’o ‘4 Io'___"__M ’— 34 £5 W131 _ Zszflfig) I/na gout/m (“—'- Mal _ ..,_¢.-_..__._____F.v...... _....-—»—- .Nw. 16. (6 pts) Consider the emission spectrum of the one-electron species X”. If the'electron transitions from an initial state of n=5 to a final state of n=3, photons are emitted with a wavelength of 142.5 nm. If the electron transitions from an unknown initial state to a final state of n=3, photons are emitted with a wavelength of 111.7 nm. What is the unknown initial state responsible for this wavelength of emitted light? OE: (ZI‘S’X/O'R—j ((2%; ’3) fléfid +0 know ‘2 HF a) 4 c) 8 (or n: a; 0:32 , c , 4,926,»:(0' 3'4) 2x108: - 2 g_.., (2.1.2): 1.375((0'53 M... M “423' SMIO 7M DE: - Lama /o"‘:>’. ’lflfixlo’IS’J t ’ZIIS x /o"3j(g:_ a: sobc 3:; 67.) 2:? new PM 2 Each m+~= Bat, amt...» +0 cm WWW level «Cw mt”. —» n:3 ‘- E: (COIGZbX/O'BH‘S'S)(§¥/Oan’23 : //7'5)C[O—I [0'7/«4 ’ » Hl.7nM( ”M > “2"“; SM“ "'7‘” "S unwed, AF: »/ 72‘x/0'”: _ .?5>(/o"?3'~ ’2. law)“ 37: 2‘ ac‘U‘ 1”” ‘ \ j ( L - "_ f—JD r/nl- C 7 \l ”('1' For ”I ‘J 2 more questions on the last page -—-> 17. (6 pts) Consider the Galvanic cell shown below: 3(Qy/lz‘f +7é’d in} A 26m —» pug” +25) N 2“ BZn’uJ zma Zlilly—I 3% 0.75 M A13“ 0'65 M 2'12" 053 L 0.75 1. Initially, the mass of the Al (5) electrode = 116 g, and the mass of the Zn (5) electrode = 150 3. Assuming the reaction goes to completion, calculate the final mass of the AI (5) electrode. Zn 2* + 2e —--> Zn (5) E°=—0.76V 2 (Wang AI3+ + 3e —-—> AI(s) E°=—1.66V 3.1425 AM i; 6‘ Véadmnh [4'5 M4“ w.“ chveaJe. a) 125g b) 103g 5"" \‘7 how [hue/la?- do sh,'¢k,'.p¢lrv7 +9 Anal 0:444, c) '2 72 'f 0.6 I2} -I l d 1° 2“; ‘5 U2 (O'?SQ< M )(ZM Au) ' O 325‘ mm» e) 13g I use MO‘C VahD +3 - gmlgm — . Mo MAW «wt 4‘ . WI COWW—k +° Ma<s fl“ (496—41 orazq M’IAIUXM 277)-5<&7 AIuwI not,» §M\>+V¢C/‘(' {mm ,,,.+ I Md§§‘. “(gr 3 8 Q 18. (6 pts) The molar mass of element X was determined by electrolyzing a solution of X3 ions. It took 48 minutes for a current of 12 A to plate out 29 grams of solid X. What' Is the molar mass of X? Note: 1 minute — 60 seconds. X7k43¢'—a x a) 140g/mol b) 27g/mol , m? , 12 ”18%" 402 m — c) 81g/mol 1' ’t A n” g: ( g>< )( M) «f, 0:358 Whale, d ‘1 g mol 904373“. a Cowl/W". 4'9 Ma\e$ Y. O,’$SS’M°l¢: (le.>/ 0,[[‘] mo\)( Ewlc Molar M4551 "1‘9. 25/3 (133/ "I Males OIHfifi/W‘ (Z I l“ W; (1 point) Make sure to mark your PERM AND TEST FORM on your Parscore. You will get one point for correctly marking these on your ParScore. .— ...
View Full Document

  • Winter '11
  • Van Koppen
  • pts, Rate equation, zducvlwma hall, ZeroordeE

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern