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midterm_2008v1ans - ’Wtwf Student ID ig f” 2 Signature...

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Unformatted text preview: , ’Wtwf Student ID # ig f” 2 Signature Lab TA’S name Lab Section MIDTERM EXAM Chemistry 102, Winter 2008 Please read the entire page of directions before you begin. Do not begin untii you are instructed to do so by your TA. You will have 2 hours to complete this exam. YOU MUST FILL OUT THE BUBBLE PAGE NAME (last, first) and ID Number WITH BUBBLES YOU MU ST FILL OUT THE FOLLOWING VERSION NUMBER CODE ON THE BUBBLE FORM BY FILLING IN THE APPROPRIATE BUBBLES THIS TEST IS VERSION 01 VERSION NUMBER ENTERED UNDER DAY BIRTHDATE DAY 01 At the completion of this exam, you will hand in this exam and the bubble sheet into separate piles, with bubees page face down. Every student MUST turn in both a test and their bubble sheet. The periodic table is at the back of the exam. You may separate that page carefully once you have begun working. Choose the best answer for each question. R: 8.3145Jmof1K“1 , 0.08206 Latm morlK-l 23 111 = 261st Na: 6.022 x10 molecules/moi 1 atm = 760 Torr (=760 mm Hg) 72: : iMJRT 1P“ [we’ll I] Asz~lemJ AszszmJ n4: _._..._. P R q z 0 1 T: 3’". PS XSPS AS‘ =—R(nA1nxA+nBian) P:XPO me I l 1.) Given that the bond energy of a C=C is 611 kJ/ mol and the bond energy of a CC is 347 kJ/ mol. What is the best estimate of the bond energy for a CEC? “’“‘ > s” _ ' 1200 kJ/ mol figfiid y Pi: :i, a, _ 4; "i ,.,_. a 800 ki/mol l3 x,‘ ashram; 129‘ 600 kJ/ mol 3"; P d) 650 kJ/mol saws; as a 5:”; new Badge e) 1000 kJ/ mol iv a: 51.5 a: '2" Egg—“c, M5 gwéfé’gflgy $50 2. Wht'thfo alch the t 'd' ' 1'? ram m , ) a JS e rm arge on cen er 10 1nz3n[ 3] 55(3) tffiai c Wilt 3‘! a) -2 I ) _1 W ” L — d) +1 i , e) +2 5 i. Z. 3.) Given the following two surfaces for a graduated cylinders, what would water’s meniscus look like? (Concave down is the meniscus for Hg in glass.) a) Water’s meniscus is always concave down 13) Water’s meniscus is always concave up 0) Water’s meniscus is concave down in cylinder 1 and concave up in cylinder II @Water’s meniscus is concave up in cylinderl and concave down in cylinder 11 e Water’s meniscus is flat 1 - l :- Smelv _ a J g f1 . m - P , _ k h ‘ <1 ‘ ‘ 6 0 Wait €11 (2,2251 g Ml iéffi'nfii’ Mi+h {SPU-iig’éétifiyé L Si”) Lfiizfgggaigvé ”/3 f1" :1 l/Vé‘l’é’f‘ {1’} «Sam ’ , W . ' l , b Lg’tflfij VJ; fiffl‘fflgg lid: Idfi<ptfiffi §fl4~gfmcgi¢fiq WK {+5.67 {1’1 /Aan.».:-Ha .r... ._ n 4.) What is the order of expected freezing points (greatest to least) for the following aqueous solutions? Concentration (mol/ kg) 5.) 6.) W mm (J Uflffil H16: a) Tfp(HCI) > Trp(sugar) > TMCHgCOOH) } b) Tfp(sugar) > Tfpaicn > momma-1) [l ffbg‘ Hm be? ll; 46 ff? QM” c) Tfp(HCl) > Tfp(CH3COOH) > Tgp(sugar) + A! H4 a d) Tfp(CH3COOH) > Tfpaicn > Tfp(sugar) lb ’9‘”?! ””" “@be Pf .T-rp(sugar) > TfiiCchoon) > Tfpmcn Hell mm nga {5.51) @ {am 7% Which of the following has the largest bond nyngle? bf) .a . ‘5. “3?." ' g y I; ‘ fl" @Gen M w (35;: 3' A?) 33. ) A31:3 i j ‘I T by? ‘x w/M\t . .— 41; , , M c) SeI2 T I a! _ LE? ,_ mg;— d) NH3 "‘ W: e) All the bond angles are equivalent 1” a g: “ig‘é‘x ' 3H :i;=§'l {MVW’V/Ehé’flfig’” my“! say.)- How many p—orbitals combine to form the delocalized molecular orbital(s) 111 the following molecule? h f /i;4 F H30 5 .e E CH3 CH3; 5, \C/ l\é/‘7\C/ \c: ffm\\£ w/ Q‘xL/b‘fia I (6 ‘ J l l l w 3? w i g/ “31/ . C. . l 5 H20 CH2 Hr C C Ho \C/ 2.2 \ n x’ 6.. II n O 53’" ,4? a 8 éD 10 {Ll-l if C 12 ' g [1 n ’ , f L!“ ; ‘1 (1)14 saw/,9 «15;, NJéfiH; e) 16 5 f A l E. l i Cw ” C, \ \‘C/ ,/ \\L / i i if; ’ :1 Hi ”I'- \ / 7.) 8.) IIIIIIEMMEIIIIII 05¢? .. d) 31.6 U K: A 102 chemistry student drew the following Lewis Dot structures for C3N3H7. Which is the best? a) ‘ WNW figbfifie -- sa+bt/:3e HSC_T—CENI HachmCE£®~'“”§>’-tmi H Ice, 20.0g, was happily sitting at 0 OC. Then an unknown amount of heat, increased the temperature to 25 °C. What amount of heat was added to the system? APIfus 6 01 k.” H101 23va C.(solid) cmuid) e) 6.79 M , f :- ins7 :23“ U1 9.) The following phase diagram is for U175. Which of the following correctly identifies the labeled phase transitions? iuoo' Pressure {Fulfil ‘_ - fffiua§~ofi {151' 25 5*?) "3‘5 “30 "125 15E] 115 2510 22.5 253i} 2?5_ _ Temperature (F) _ --—__ m Sublimation Liuidification Anti-sublimation Sublimation r—q Sublimation De-osition - Sublimation Melting Condensation B---.- Sublimation 10.) Which of the following structures would you expect to have resonance? g Condensation a) CH3CN H?) i “<1 "“3 M 5‘?“ c b) [0131‘ 3511i 5 i?" if 9 c) CH3CH2C02H , 3:3: “25"?” C\ ,x’?’ d) C2H4 ox. =._ (lit *"l «O: {3): [N02]' or '* ‘H 11.) You have a closed mayo jar with two test tubes. Test tube A is filled with 25% benzene and 75% water (by volume) and test tube B is filled with 50% benzene and 50% water (by volume). Assuming ideal behavior, What would you expect to see at equilibrium? {3 p a Mole fraction of water in test tube A is greater than test tube B "E9 ”i 5‘52"} f3 @ Mole fraction of water in both test tubes is equivalent ) Mole fraction of water in test tube A is less than test tube B d) Mole fraction of water in test tube A is l e) Mole fraction of water in test tube A is 0 12.) Order the following three molecules from highest expected boiling point to lowest. 3) prU) > prm) > M111) > praV) b praV) > pra) > pr(II) > prafl) @ pral) > prall) > praV) > pra) d) pr(fll) > prfll) > prG) > ThpGV) 6) ThpUH) > pral) > praV) > pra) [3 .2" . —~< ‘ a s ‘ I ' A I -. 5 119% s/li'e/etti,% W? 3.1%“; 53315523} {9545313101 w it em: >31 >1“ 13.) Why do you put salt on the roads after a snow storm? a) Tire traction b) The salt absorbs the water c) Energy is released upon its ionization to melt the snow d) Salt forbids snow’s existence Salt depresses snow’s freezing point 14.) What is the absolute value of the difference between the AH when calculated with heats of formation versus bond energies for the following gas phase reaction? )112.37kJ/ 1 ‘: ' a: - a . a. , A 2) 447.63 kJ/Zgl “fills” grille {Wits-.345) ~£=4HX:‘eedeea>$§5§,é9~9:ea)“35;;ng c_ 377.37 kI/mol M , ._, ‘11.63 kJ/mol '" 379‘— :51 OkJ/ l “'3.“ '" ' t . " .I ~— , e) m “filler?“ {rce'deméetawiweg alts-ass {avg fish-figyfifl: M Q 1 15.) What is the normal boiling point of pentane? ‘8" 30‘} if”; 1%} w 5' a) 14.9°C Mi 55315;? ) 43??§‘¥5‘»:?;; M *:*j Q; 36.3 °C .3 , _ 0 412°C 117,271 a: ‘3‘.“ ”W; K Mm d) 62. 0C m; . 1 - K , “224% e) 19.0 °C “*1 13%;? 3/1 MW; W? 16.) What is the definition of lattice energy? a) The energy required to dissolve a lattice in water ‘0 The energy given off by combining free, gas phase ions into a lattice Q The energy required to break a lattice into its free, gas phase iOns . The energy required to break the lattice in half e) The energy released when meiting a lattice 17.) In the foliowing unlabeled molecular orbital diagram, which statement most accurately describes the orbitals in the box? A 0 a) The atomic orbitals that exist in the molecule . b) The atomic orbitals that exist on one atom in the molecule ”.135“ cu trig/s it'- 9,55%}; c) The molecular orbitals that exist in the molecule all’tfi’ Qmmfi 533,35} d) The molecular orbitals that exist on one atom in the molecule / F ® The atomic orbitals that exist before the molecule is formed is.) 19.) d Sb a—w why“? 4; d i @AHms You have an unknown solid X that is composed of a single atom. X—ray diffraction measurements inform you that solid X has an atomic radius of 142 pm and packs in a face centered cubic unit cell. You add 20.0 g of solid X into a graduated cylinder containing 50.000 mL of water and the liquid level increases to 51.735 mL. What atom is solid X composed of? (Hint: Do not round until final value is obtained) Q52 (:43); a) He p: (Maggie 513) x U SE 7 gig, b) Tb c) Cu met/Mil alarm 910;] The portion of a heating curve where the slope equals zero could give you information about what physical quantity? in) Cp(solid) _ l c) Cp(liquid) ' d) Cp(vapor) e) Not enough information given Which of the following valid Lewis structures is NOT a valid resonance structure for [31204]”? 21..) 22.) 23.) 25.) 10 Which has the highest precision for measuring molecular weight? a) Melting point b) Boiling point Freezing point @ Osmotic pressure Depends on the molecule One day in lab Lisa made a SIS ionic crystal (MW = 119.69). After collecting X— ray data, she learned it had an edge length of 342.95 pm and packed in a CsCl—like unit cell. What is the density of this solid in crystalline form? L7) f . -é:a.:xeuf:£; Liar fl]; @4. 93 g/ 01113 b) 19 38 g/cm “667:? léxmf’efl 3% 32656” dcii‘ c) 9. 69 g/ cm3 3 p : M3] gmwmm ”newly”?! d) 0.208 g/ cm (33:36; 6;J )5 iflfiwfl 3 6) 0.0520 g/ c1133 _ '2: ' e- 3' L-{R ‘53 %;%3 Which of the following 13 diamagnetic? 3&3 : $5 M “‘“h. {PW/‘3 a BN_ W? “N E “If”. w W 13 BN+ 211.4“in ”,0 x K m... m 0) EN . 3?. M M I d) EN2+ ;: 11’ “$471; 23 3 3, .3. 6) All answers are paramagnetic .54; 691’“ it 3,3; hi; '7 a mi 34.2 What is the hybridization of a AX4E2? 13ij “— 5‘: b) SP3 ‘36,”? A” x 6) SP 34’; . i d sp3d l K a ‘3. ”2; @5936? [a “'3 ”j What is the electron pair geometry of a see—saw molecule? a) trigonal planar 7; b) tetrathedral g trigonal bipyramidal 6/, i; r K octahedral a \ e) square planar l ' ?<« 11 26.) What do you know to be true from the following graph? Normal Boiling Point _. -. fiflfi {j 315:5; tirxwer if? 'Tlf'j‘imy? A 520 if“ 555 flea??? ifflififi'yfi (glee: @025 fioi {"3 ,3 A Mote Fraction of B B a) Mole fraction of the vapor phase equals mole fraction of liquid phase - . b) Mole fraction of B in the vapor phase is less than in the liquid phase "7i£g(i/aflgr):3 X {is w ‘64" c) For the mole fraction of A to equal 13, B has to be held at a higher temperature :3 t 32 i , @ PAC < PEG 8) PALw PB 27.) Pick the true statement about the vapor composition of a solution that is 75% A and 25% B given that the minimum azeotrope occurs at a liquid composition of 75% A and 25% B. a) The vapor composition is greater than 75% A b) The vapor composition is less than 75% A A . c The vapor composition cannot be determined without a vapor pressuize curve W4 ‘The vapor composition is 75% A game. as "flag 5 [flrxgtj e) The vapor composition is 25% A 28.) Determine the molecular weight of protein Y, given that a solution of 3.50 mg of protein Y in 5.00 mL of water had an osmotic pressure of 1.54 torr at 25.0 0C? a) 2.78 x 103 g/mol If -—- [we is T b) 8.56 x 105 g/mol M . q 1 _ (1‘0“ k ° _._ _ . c) 709‘g/moi mm [:f’” 3,; 3*“ 'v WW5 ‘. mg; g 9 2.78x10'3g/m01 ewe” ; .. . e)§ 8.45 x 103 g/mol be .r 12 29.) -Which of the following has the longest bond length? {0%, M‘tivi'wmmbeafinéamaj “12:2,” 3.:— 2..., .___ .,._. w. a) CO" (1;: .1933: M: 2—2 M m {(WE‘J r £0? b) CO+ 8 _#g 192911;: “.3; ”“2 13 it “3&- “32:” ‘2” iflfl“ £22 .. 3 2160 £2 M?” ,. :2 :2. 2222-2222 (302+ ‘9‘ ML ’1 ‘2 122 "‘- . . 23.35: 22-2- 2 .232 6) Not enough information .. C :L £022 ' 3": CU f; _ P; {3’ ” ““2, ’2‘. :72 9x29 30.) How are molecular geometry and hyr rid orbitals related? (Hint: Find counter examples.) a) If you know the molecular geometry you know the hybrid orbitals 2’ b) If you know the hybrid orbitals you know the molecular geometry {g Hybrid orbitals are not directly related to molecular geometry 2’ Both a and b are correct EléE’C-tééifx (:62:er a: [Marc-{Fm I} .375, 27/”33 5f) (fig/:3: if: ) Ill/I]: 2d $f§71flflollecw 2‘2 (31:22:22, 4C 2.22: 42222522; 17 fidwa/ [fir/$72244; {gig/ML” EmammmBmim” Em 31090556 0: 5m Eozaéam Emu Eéé.émcm_m3m2m.83 w h m m .w m m .8 .3 2m” £255.: nuim mnoamn 5:232. mammafa *mmsflrmzoam imflioam minus? 2.5 33mm” :6 $330? man .522. 3 2% £361? man :6? www.mwzmm m8 303 3833253 3 25 .qusmwosmw can: a“ van» man 5633 95in ccgn ‘ Kauai/Egg.“ owns. 29.3“ :2; «R 8 am 96:38 a: :6 Bow" $825.. 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