KEY EXAM 2 SPRING 2008

KEY EXAM 2 SPRING 2008 - l<€Y.fl’ Lab Sec TA Lab...

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Unformatted text preview: l<€Y .fl’ Lab Sec. # ; TA: ; Lab day/time: Andreas Toupadakis, Ph.D. Spring 2008 Good luck © CHEMISTRY 23 Section C EXAM 2 Multiple Choice (circle one) Ins fruc f/‘ons.’ CLOSED BOOK EXAM! No books, notes, or additional scrap paper are permitted. All information required is contained on the exam. Place all work in the space provided. If you require additional space, u5e the back 4. 2 3 of the: exam. A scientific calculator may be used (if it is a programmable 5 calculator, its memory must be cleared before the exam). _ _ 6 b c d @ (1) Read each question carefully. This exam has 9 pages. 7 8 . a (2) For Parts I and II, there is no partial credit given and only answers - a b C d {:2 marked on this cover page will be graded. a b c d @ (3) The last page contains a periodic table and some useful information. 9 [email protected] 1 -9 total palms: You may remove it for easy access. (4) If you finish early, RECHECK YOUR ANSWERS! U.C. Davis is an Honor Institution W Possible Points Points #149, (4 points each) 10- 13 total points: (8 points each) 3 # 14 (8 points) # 15 (10 points) i #"16 (14 points) Total Score (100) Name Spring 2008 (Page 2 of 9) EXAM 2 ParT I: MulTiple Choice, Concest (4 poinTs each) SelecT The besT answer and enTer your choice on The cover sheeT - No parTial crediT 1) Which of The following equilibria will shifT TO THE RIGHT when H20 is added? 3) 02(9) + 2 H2(9) 1: 2 H20(9) 0) 2 HI(9)‘_: Hz(9) + 12(9) c) H20(g)+CO(g) t; H2(9)+COz(9) d) 2 NOHCO3(S) 1:; N02CO3(S) + HZO(g) + COz(9) 6) 2 CO(g)+ 02(9) 1:; 2 602(9) 2) Which of The following will cause The equilibrium: 2 CO(g): C(s) + COg(g) To shifT TO THE RIGHT? a) Decreasing The volume b) Increasing The volume c) Adding more C(s) and mainTaining The volume of The gaseous mixTure The same. v d) Adding 602(9) e) Removing CO(g) 3) Which of The following expressions is equal To The hydrogen ion concenTraTion of a 1 M soluTion of a very weak monoproTic acid, HA, wiTh ionizaTion consTanT K0? :1) K, b) K,2 c) 2 K, d) 2 K02 e) \/1\— 4) For which of The following reacTions will a change in volume NOT affecT The posiTion of equilibrium? 0) M90(S)+COz(9) 1: M96036) b) H2(9)+CI2(9) S ZHCKg) c) C(S)+Coz(9) 1:; 2CO(g) c) BaCO3(s) 1: BaO(s)+COZ(g) e) BFZU) + H2(9)3—_> 2 HBr(g) Name_ WinTer‘ 2008 EXAM 2 (Page 3 of 9) 5) The anion OH'(aq) is a: a) MonoproTic base b) DiproTic base :) TriproTic base d) TeTraproTic base e) None of The above ©AT2008$PRING 6) Which of The following salTs will produce an ACIDIC soluTion when dissalved in waTer? 1) NaClO b) KF C) Ll2CO3 d) BaClz e) AlCl3 7) The sTrongesT acid is: 3) H20 b) CH3COOH c) CHZFCOOH d) CHFZCOOH e) CF3COOH 8) Which of The following would cause an INCREASE in The percenT ionizaTion of niTrous acid (HNOZ) when added To a soluTion of niTrous acid aT equilibrium? 3) NaNOz b) HNO3 c) HCI d) AlCl3 e) H20 9) Which of The following combinaTions can be USed To prepare a buffer? 3) HCl/Cl ' o) NaOH/NaCl C) HNO3/NO3‘ d) CH3COOH/ CH3COONG e) None of These NEE“..- Winter 2008 EXAM 2 (Page 4 of 9) Part II: Multiple Choice, Short Calculations (8 points each) Select the best answer and enter your choice on the cover sheet - No partial credit 10) Consider an aqueous solution 1.0x10'7 M of acetic acid (a monoprotic acid). Assuming 100% reaction at this high dilution, the pH of this Solution is: ©AT2008$PRING a) 6.98 + b) 6.95 QRzOMl f7 H30 (om + OH (am c) 6.90 + — ~l d) 6.85 Kw :CHaolfonjzioxio L‘ ) 6.80 [H%O+] ": [H%O*]Hw + [Hsoljodd : (j) «\r (LOXiOaj) - t » - lk wifle he: 3 ‘: [HKO-«leZLOH—lllw 4 LONG“? M w cl - “ L‘ A; 71 t(l~0xl01)Y'l.Oxl0 :0 Eu (3 4} Loxn04)(fll :LOMO -8 - - \l ‘1 6.0. 5‘ l0 : [OR] 910 : [OHltotuZ iu eq. a POHZ~1€03 (6.1xl0‘8\ cq-Ql .A-B PH: lL‘Do‘TL’M @) 11) An aqueous solution is 0.03 M in NaOH, 0.04 M in KOH, 0.03 M in LiOH, and 1.00 M in ammonia. The pH of this solution is: ©AT20085PRIN6 a) 13.5 b) 13 NOLOl—\ 0.0%!“ M [OH—1 : 0.03M c) 10 d) 8 \/<o\.\ ooum N [0H’3:0.ou M e) 5 ’ l..\ OH 0. 0% M ”\a COW'B : 0.0% AA NH?) 1.00M fl [0W1 a; o M \~\10 ’\-‘9 COW-l ’: O M ’ro¥o€ [OH'j ’2’— O-l M :Lxlofll M. pUll $60k COW): ’60:) lo" : 1.0 Pll t \uoo— L0 lflarne 7 Winter 2008 EXAM 2 (Page 5 of 9) 13) 12) Consider the isomerization reaction below and assume that equilibrium has been reached in a 1.00 L flask with [butane] = 0.500 mol/L and [isobutane] = 1.25 mol/L. KC = 2.50 Butane(g) t; Isobutane(g) Then 1.50 mol of butane is added. What are the concentrations of butane and isobutane when equilibrium is reestablished? a) [butane] : 0.500 mol/L and [isobutane] = 1.25 mol/L. b) [butane] = 0.93 mol/L and [isobutane] = 2.32 mol/L. c) [butane] = 2.00 mol/L and [isobutane] = 1.25 mol/L. d) [butane] = 0.600 mol/L and [iSObutane] = 1.40 mol/L. e) [butane] = 0.800 mol/L and [isobutane] = 1.95 mol/L. thumfi (3] :77- lSOlOUVUMC (ll) lvnliofi CAM 0.800% L§o Lil’s fol/wing: CM) -—x ix éqoilcibh‘uum (Ml (1.00 vx] C l-lS ’0‘) kg :1.§O: [isgbulwej A) 1.§O: (JYK'X ,4 X: 1.0? wvelL fbotuue‘l ’1.00~—3< :L {home/3:083 M ma [isoboiwa : 2.17. AA. Mixing 50 mL of 0.20 M Solution of the acid HA (K, = 1.0x10'5) with 50 mL of a NaA solution a buffer solution was obtained with a pH = 4.00. What was the concentration of the NaA solution? a) 2.0x10'2M .. i. b) 7.0x10‘3M H A (0m JV H1060 : Amen * H’sOuxcn c) 5.0x10'4M d) 9.0x10‘3M \4 we uSQowt \no mm at o1€ e) 8'0X10‘2M HAevx the mixm 04 We éwo ) goeuti‘ows lwfives HAé COWUVHYQMCMA Lfic €QC\/\ goéule. 3 R“: W] __ XCLoxio v '— CHA1 (040) ’T‘Lle OV\:‘)\V\O.X. NaA §O‘€U¥\\OV\ V\’\\)§4' be: (1:0 ’< lat/ill ho 6d ‘l-(AK VOIKUC o’l’ )( Q’fi‘l-Q/‘J’ d; QU‘H 0W- ‘Name , _ Win’rer‘ 2008 EXAM 2 (Page 6 of 9) Par'T III: Par'Tial Cr‘edi’r May Be Given Please show ALL work for calculations 14) (8 points) If Kb (NH3) = 1.8x10'5 and K0 (HF): 6.6x10’4,find Keq for: NH3(aq) + HF (aq) S H4N*(aq)+ F'(aq) keg : IiNHL‘flEF'] éq. ’1. 5 2‘ l”)1r CNHfSEHF] V , l - H?) N (uq\ Jl’ H10 CU <1"? HLlN (oq\ ‘\' OH (CAI-13 '1 W \ k - I + ' ‘Kb‘: [NFL‘ 1[OH3 ~—> “En/HQ]: kb 6‘1?- (“IN L \-\3 N1 E NHKAX COW} K) ,5 . 4 _ H; (uqx l HiOCU <‘ \“\7>O (can ‘\' C (uqs *" ,. I H O+XCFJB ' 0L - \Ao. : __——-—-————~C 7’ M [F 1 *: k (‘1-3 J C HF) [Ml ENG“? 29“ / (LUV/L beoaose 0’»: gel/l a” 6‘3 bfcoweit . _,'“\ k’ecl : Kb . .Ku Q Ku‘kb p C6.GXIO'L‘)(‘~G>lObS) /3 COM") Crud} Kw ' l ox l 0"” (i (Z; 6 j! «Lg? 'Ngme H Winter 2008 EXAM 2 (Page 7 of 9) 15) (10 points) D-e’rermine and sTaTe which Bronsfed-Lowry base, F'(aq) or H200) is stronger by showing your work. Compare Their s’rreng’rh by comparing The equilibrium constam‘s of Their reaction with The common “Cid/ H20“)- KG(HF) = 6-6X10'4 ©AT20085PRING 4. ’ . ‘A ' ; (0‘3“) + H10 (e‘ T— lig (OCH -\> OH (0% w,\\ __ u' [:1 ‘ mam , 6-6 “0"”;3/ Kb (gj __ Cnfl [owl Kw i‘OXiO’WQ ’ / JD“ 3c KbCP’) : LSXiofiu i/ . ‘i’ .. HlOMi Jr HzOCfl Eb—HsCNWJF OH (mi) 1 r7 ,4... ‘wt Kb (H10) : CHsofifoH'] «2 WHO-m \; 5 Kb (F') : is xiob” W Vi. [ kb ( H10) ~: \.o “0'“ \>z‘l :1 awn-is o gimw base Him Mom V baa/use RbCF’3 > [(5 CHtO> . i Name WinTer 2008 EXAM 2 (Page 8 of 9) lo) (14 poinTs) In a 10.0 L evacuaTed chamber, 0.500 mol H2 and 0.500 mol I2 reacT aT 448 °C. AT 448 °C for The reacTion below, Kc = 50. (a) (b) (C) (d) (OWE-X3"L H2(9) + 12(9) S 2 HI(g) WhaT is The value of KP? WhaT is The ToTal pressure in The chamber when The chemical sysTem reaches equilibrium sTaTe? How many moles of iodine remain unreacTed aT The equilibrium? WhaT is The parTial pressure of each componenT in The equilibrium mixTure? A V\ 3 k9: kc<l1T\ Dm3:1—1i3:o kl): kCCQTlo : ka/L : kc As HAe mm pmacds The lolc‘J it of vvmfiS C303) \(tvvicu‘ng HA6 §QAM€ OSTOSVL ( \ 3 vad hue, PfeCCUYe. \N\/0 YWCA“ *Mfl gWC QI‘V‘CQ 7 4; V owe, COwCTOAA‘l Oahu») (_ Kp=50 @g-x) @S‘Xl Clxl Pioiuiieqi=59afm L n (unreacTed I2) = 0.11 mol (1") : kc : SO M x: 039 PHZ (eq) 2 0.65 aTm \ _ P (e )=O.650Tm V\ (IL Unveucl€d\ '37— 0-C "' 0.29 :@ PI2 (e:)-46aTm HI ' ' {All (3 L11) : V\(I1) Pick”— Om 9% .m \AC‘CUH 1 . P“: -; PM- PcthU-M{giq'O-Gg‘o'égluw- Name _, Winter 2008 EXAM 2 (Page 9 of 9) Periodic Table Key 1 1. Atomic Number H ’ Symbol 1.008 Atomic Mass 2 20 l Electronegativity 3 l 4 10 Li ’ Be Ne 6 941 I 9.012 10B 81 12C 01 14b] 01 16. (300 19 F00 2018 2 04 2155 3.104 3 44 3 98 . O98 . 1.57 11‘12 17 18 Na Mg Cl Ar 22 99 ‘ 24.31 26. A98 28S 09 30P 97 32 506 35. 45 39.95 093 : 1.31 1.61 1.3920 219 2.58 316 — 19 20 25 35 36 K : Ca 5c Mn Br Kr 39.10 a 40.08 44.96 50V 94 52.00 54. 94 55. 85 58. 93 5:] 7'0 63. 55 65 38 69. 72 72. 59 74. 92 78. 96 79.90 83.80 0.82 “ 1.00 1.63 1.66 1.55 1.83 188 1.91 190 1.65 181 2.01 218 255 2.96 . 37 38 Rb Sr 85.47 87.62 0.82 0.95 55 56 Cs Ba 132,9 1373 175.0 178.5 0.79 0.89 87 . 88 Fr Ra Lr (223) (226) (260) 07 0.9 4147 54 Mo Ag Te Xe 92. 91 95 94 (98) 101.1 102. I”9 106.4 107 9 mad. 4 114. n8 118’I 7 121: 127.6 126 9 131.3 2.16 2.28 220 1.93 1.69 178 1.96 205 21 266 , 86 Os Ir Rn 1810: 9 183W. 9 1816: 2 190 2 192.2 1951197th 22009. 6 2014'. 4 207b. 2 2:9. 0 (2:03) 2. 36 2. 2 2.20 2 28 2. 54 2 04 2 33 2. 02 , » 106 Univ Unh Un: Some useful equations and data: P-EASE NOTE: Important values and equations required for calculations are given with the respective problem. The following may or may not be of any use. pl] :: ~100[H O ] ‘ pOH = —log[0H ] = —logK pKw =pH+p0H =14.00 Kw =Ka Kb pKw = pKa+pr :14.0() K =ng0 ][OH 1 l Kw=1.0x10'14 [base] — b i 482 4 4 -a KP = KJRT) A” QC = products / reactants MM. (HCI) : 36.5 g/mole J logx = a means x = 10 ‘1 ...
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