CHEM123 - DEPARTMENT OF CHEMISTRY CHEM 123 - Term Test #2...

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Unformatted text preview: DEPARTMENT OF CHEMISTRY CHEM 123 - Term Test #2 Friday, March 7, 2003 Name (Print Clearly): Student Number: Signature: a Aids Allowed: Electronic CalculatOr Time A110wed: 90 minutes Instructions: 1. Fill in the top portion of the 00mputer answer card. Make sure you fill in the ovals for your ID number. Circle your section. C. Chieh C. Bissonnette R. Le Roy Section 001 (8:30 am) Section 002 (9:30 am) Section 003 (1:30 pm) 2. Attempt all questions. No marks are deducted for wrong answers. 3. Circle A, B, C, D or E on the test booklet. Then transfer your answers to the i computer card. 4. Do all rough work on this test booklet. 5. When you are finished, or when time is up, turn in your computer card and test booklet and leave immediately. Note: The last page is a DATA SHEET, You may tear it off for easy reference. n Winter 2003 #0. #1. #2. CHEM 123 Page 2 of 10 You are writing Test Version #2. There are eighteen (18) questions on this test. numbered 1 through 18. Before attempting any of the questions. fill in the ovals 002 for the Card Number on the computer card. Which one of the following statements is correct? HHS) is an ionic solid. -/ HHS) is a c0valent solid. I-U:(s) is a molecular solid with dipole-dipole forces providing the major source of attraction between pairs of HF molecules. PEG) is a molecular solid with London dispersion forces providing the major source of attraction between pairs of HF molecules. HHS) is a molecular solid with hydrogen bonding forces pr0viding the major < source of attraction between pairs of HF molecules. .2 3‘3. Iridium (Ir) crystals are cubic. The densityof iridium is 22.61 g cm"3 and the edge length of the unit cell is 383 pm. How many iridium atoms are there per unit cell?- WUOFUI? one two four eight twelve / s. _ r'. . Winter 2003 #3. #4. #5. CHEM 123 Page 3 of 10 Which one of the following compounds has the _lp},__i_;.§§,t boiling point ? A. 1-120 »/ ~— B. H; K C. KBr‘ NH3 .E. HP in For Zr14(s), the I" ions form a face-centred cubic lattice, and Zr“ ions occupy some of the tetrahedral holes in the lattice of l ‘ iOns. What fraction of the tetrahedral holes is occupied? I. ' ' A i ‘ . 2 - 1 E g C 8 c. i , r. D. é“ , r ‘ . ' \l l l Which one of the following statements is false? ( i L L. '_ In a cubic closest-packed lattice. the layers have an ABAB... packing sequence. - B. hTt-he simp'l-e‘cu-bi-c structure, the edge length of the unit cell is twice-the radius of a sphere. T _',. C. fn‘cubie-closeh-pacldng'of iden—ti-ca—l spheres, thela-ttice i-s face—centred cubic. T D. [mall ofi—thecubic—packing arrangements, only one—eighthpf'the sphere—at—the Corner is inside-a given-u-ni—t-cel-l. T E. Among the simple cubic (so). body—centred cubic (bee) and face-centred cubic (fcc) packing-models -, the fee. structure has theiargestpercentgge ofthe Space occupied by spheres. T Winter 2003 CHEM 123 Page 4 of 10 #6. The chemical equation for the isomerization of cyclopropane to propene is CH2 / \ —> H20=CH—CH3 H2C—0H2 Cyclopropane propene The reactiOn is first-order with respect to cyclopropane. If it takes 34 minutes for the concentration of cyclopropane to decrease from 1.0 mol L4 to 0.25 mol If]. what is the rate constant, k ’2 L{ {I- ‘ -,-L.: mm A. 0.088 mm' 4‘" 7‘" mam 0.022 mol L" min" {we (Q 0.041 min“ > 3.11:: 0.029 moi-1 L min" K " E. 0018 min" 2 #7. At 300 K. a certain reaction is exactly .iimes faster when a catalyst is used. What is the difference, AB”, between the activation energies for the uncatalyzed and catalyzed reactions? : t< A. 361dmor‘ 7,3 Q 1 Q17?" B. iikjmoi“ “is _ __ {221% @ 8.0 kJ mol'l t,“ is 2 (c. you 1 Fri-o D. 4.7 kJmol" (m 1% (a . T. : t CK E. 187 kJ mot" tame too“ * R : M e ': pic z'ws :5 i‘ mir it Winter 2003 CHEM 123 Page 5 of 10 #8. For the reaction 2I_(aq) + H3A504(aq) + 2H+(aq) .2 13(04) + H;AsO_-r(aq) + H300)s the following mechanism has been proposed. . t.- - E" k u - A .- ‘ ‘ I H3AsO4 + H+ —’(_k_l—>w HAAsO; (fast) ,le A k"! L... ..,. HAAsO; + I' A H3AsO3 + HOI (slow) ' ' k H k (II-{whgoif‘l‘ . HOI + 1‘ + H+ —_—3—> 12 + H30 (fast) ' ‘ " r. What is the ratefiiwfgr the rate of production of H3ASO; ? c____ I“. h \_ . n _ _ ' ' iL. M. fish _L A. Rate =k1[H3AsOA][I-I+] ' \ B. Rate = k1 — k_, + k2 + k3 ‘ ' (3. Rate = (k, —k_, + k2 +k, ) [1']2 [H3A304] [H‘]2 _\ K, . _ r «' {kk \ “(if—i [H-‘Mii 1m“. " _ 1 3 i - + . .I .I L13) Rate—L k1 l-[H3ASO4MI ][H 1f: _ / kk. , + E. Rate =[ I; - ][H3As04]' [H ] —l #9. For the elementary process A + B —> AB. the a_(_:_t_iva_tj9n__e_nergx__is ‘S—ilklmofl. The enthalpy change is 42 kJ mol". What is E, for the reverse process? . . _-_. I”. A. 54um014 a ' ' g I :5. a 5—m- - n B. —54 kJ mol‘l LL. : mm... 5 WI' @ 12 kJ moi" T D. —42 kJ moi“ Eur fiH I: Law gm: ‘ E. 96 kJmor‘ v Winter 2003 #10. #11. CHEM 123 Pageé of10 For the reaction 2 Hgfii) + 02(5)) = 2 HgOG), what is the correct expression for A. KC : [Hg] [02} 1:- 3“ [HgO] [Hgoi' H o 3 c KC =—[ gr ] [Hg]‘[02] Di“ Kc : 1 [Oz] E. Kc = [02] The reaction Brz(g) + 02(3) = 2BrCI(g) is studied at constant temperature. At the temperature of the experiment, the equilibrium constant is Kc = 3.9. me___i_n_i_tigl concentrations are [Brz]O = [Ciz]O = 0.10 mol L‘| and [BrCl]0 = 0.50 mo] L", what is the equilibrium COHCentralion of [Brz] ? E 0.18 mol 1;1 k. - . I; h B. 0024 mo] L“' ‘ k C. 0.56 mol L" -- D. 0.12 mo] L" [firs : 0-K H ' 1 O ‘7‘” E. 0.08] mol L“ ‘33 ,t .':< m 1 J _ . ii\————r;i_;r :.‘ L ‘4 g R I 0.1:) +X/I F ‘12-?23‘1 Li (5’! ‘ I i q 3'1 1- F 1 t E“. 1 ’ ’ 71,1411}? 0 I tip-q 1 A. t i- L 7' - 1 0.11 _. 1% 0.11 H '17" L f7 P 07%) t k____'—— ) .. Winter 2003 CHEM 123 Page 7 of 10 #12. Given that H2503WI) + 2H:©'('l) = SO§‘(aq) +fifi;®*(aq) ’“ Kc: 1_3x10‘3 .1 a] ii), ') Mia _ 2Hzou) = Hgo-Xaq) + OH ‘(aq) Q44..ka = 1.0x10'” what is Kc for the reaction K _ k I {or‘ {- H2503((1q) + 2OH‘(aq) : so§'(aq) + 2H20(() 7 _ kc K.) - 1 A. 1.3x10"6 ‘ -- C‘éf‘k : tr U“ B. 1.3x10‘2 -1 I [.1 “:1 mg —|3 '\_/ _H________ "1‘ C. 7.7x10 I (ho “0-3) . D. 7.7x10’27 — -. “a - l': L 3‘- I’D CE) l.3><1026 #13. A 4.00-mol sample of NOC] is placed in a 1.0-]. vessel. The sample decomposes according to the chemical equation 2NOC](g) .——~ 2NO(g) + C|2(g). [fa-fl a At equilibrium. the concentration is 1.32 mol L". What is K for the reaction r above? -' ' r'r.I\ 45x 0" @— 016 "53' W ‘9 (5!? B. 2.85 Q ~:. tin-i W‘- Ls ml NO f) 1.2th (L. In .-.c_z,{-_;.,_.._ I W's. ' c. 0.020 2;... Lot. v‘fiw-J» fNOCLl?&_'kQ .699 -. “1 r. 1 D. 0.33 L .’__ kc = EN"; L U- E. 0.072 L " ,. ,.\ ,. - '~ H E . r*--' --; 0qu . Begun k1“) I .L I [fl/x ‘ C I(,/‘!'_'-_‘._!.J ' L;/ "i 22> 1 K _ Q $251 (0,230 (may . ' L Winter 2003 CHEM 123 Page 8 of 10 #14. The following reaction comes to equilibrium in a closed reaction vessel. so) + 02(g) : 502(3), AH < 0. —> Mow-m. Which of the following actions increases the mass of SO; in the equilibrium mixture? A. increasing the volume ifthe reaction vessel x " 03’ C. D. ' __ vesel x/ ) / «tel , t ‘ i \If , t \<' adding a small amount of sulfur K 4‘ M fi "' a w“; '3?th L351; "' d _ kc o " .l E. removmg a small amount of sulfur >< : - L o“, #15. Whatisthe pH ofaO.lO mol L" HOCl(aq) solution ? (K. = 3.5><10_3) ' _ ._ H-a. lrcto‘jil'll’): Al KO‘ ._, f, (Isfx v, n F fl—h—f-d—“F [HOCLj B. 7.45 C 846 7” l“ {CW ' ft” “3 D. 3.73 r E thO‘l . '- n 1 v: m " r f!”— - - .. .' J" - LHQELI (‘9 4.23 . ~ 1 "< {uncut :. '{ ____ (out: rig e._- a : . A x . ._ h CHEM 123 _ Page 9 0f10 Winter 2003 NJ- TP) 0 Ell-Ii” L14- 1' ’i‘iflfi. What is the pH of0.0020 mol L" Ba(OH)3(aq) at 25°C? (K. = 1.0x10” ‘4 m 25°Ci",”' ' .. S": _ i A ll 60 a ., ‘ (In : - l. ii... {all}. i m r“: c; How- . - ' ._ J - d If. r“? I .- rll“ 'r,. B. 11.30 |‘--.l I, if L h" [‘9' ii I \J .i f. -13.. 340-. - L _ , l. . E. 9.70 R L n _, y I . ‘_ in}. .- _ _ _ I N21. :' ‘ 'Z" I‘ " Cgéé‘wéséiéhm- ' ' _.;=" lm-I a #17. A 0.10 mol L’1 solution ofa weak monoBrotic acid, HA, has a pH of 3.70. What is K3 for ' this acid? _ LI". J/ A. 2.0x10‘" B. 2.0x10“ i»- @ 4.0x10‘? m U. 5 o. 4.0x10‘8 "" - ‘3 u ,z. L001: 3 It)~ I E. 2.0x10‘9 1 I: t C' “A P i 1‘ I" i r" t1 .I._ 2 -p as y " #18. Which of the following is n_0t a conjugate acid-base pair? A' H20 and_OH_T “- . U 1 l "J' . LI) '::. HAW! 1- -'|.‘ H3O+ and OH‘ e—f --\ C. and CH3NH2 T I 0.. Nu "51.0 Q|l.{i‘f'-.‘agl * '13’ '1 D. NH3 and NH; 4,. r.- " ' KI - 2— f) . O I. “I IIJI ‘ O a” _‘_ TM; H 1 l 0 rung ' I ~ l' {fig \ H H N L: C'i'l' ...
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This note was uploaded on 08/17/2010 for the course CHEM CHEM 123 taught by Professor Oakley during the Spring '08 term at Waterloo.

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CHEM123 - DEPARTMENT OF CHEMISTRY CHEM 123 - Term Test #2...

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