midterm1solutions_2005

midterm1solutions_2005 - Page 3 of8 Mid—HIM ' Print Name:...

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Unformatted text preview: Page 3 of8 Mid—HIM ' Print Name: q CHE [OLIWJ'M’M 2035 i i Choose the best answer for each question. Fill in the answers on your scantron sheet. There is one-and only one answer for each question. I. How many lone pairs of electrons are found in the Lewis structure of urea, (NI-[2)3CO? A) 2 :0: B) 3 H l 6 C DJ / \ _" H , 8 H H 2. Which ofthe following would likely dissolve in benzene? H 63 NaCl I? é: C13CCC13 H ,C [wk / \ C) N83C03 \ (L \\C’ H C, H t D) Ca(I-lCO_t)g ’Cl A H é—é I H ' l “r H 3. 4. 5. Use the bond enthalpies given to estimate the heat released when l-bromobutene, CHtCH3CH=CH3. reacts with Br; to give CHJCHQCHBTCHQBL Bond enthalpies {k.l'mol") : C-H. 4l2; C-C. 34s; czc. 612; C-Br. 276: Br-Br. 193. H H #4 H H H A) 181 klmol" ‘T‘ if n i y r _ _ -C: (“—3) C.‘ C‘-— -- — B) 3l7kJ'moI' H'CF .C CF 8 C '14—; , E” g— H C) 288 kJ'mol" H H H H H 5r Y‘ E (4123+ 2648’) HatILH‘iSLLl'lCl—l “my” 3648) ‘r 2(QJLO) ; 1.1%th 95 “mo!” 1 507 kJmol" \‘t'httt is the shape of Bros"? tetrahedral 7 7-4132- fl f! B) lrtgonal bipyramidal " q " “95164.! C) seesaw D) T-shaped E) square planar Wlumm Hon many (3- and TI- bonds are present in the cyanamide ifip’, NCNHg? Al33nd3 5452: :16 4 and 2 ('14 and t) _ _ H DlfiandO E) 4 and l ‘ ® 15. C. ~ 0 o o \ H M {CHM ‘M I Page 4 of8 Print Name: k C‘HE- K52, 2—035 6. The hybrid orbitals used by the underline atoms in CH3§HCH_C_N. from left to right respectively, are W 2M Pia/mad _ 3 'A) 5131 H H H -5315513' and Sp I I C) sp‘ and sp3 H. C—E: C "jg—E N I Dlsp2 and 5p2 11+ 1 (MC E d v 3 a “pan 5p becauseg‘owt has one H. 3L ‘ dualism bash I‘S lMPlt'Ctg l’O pusher ll 7. The vapor pressures ofpure carbon disulfide and carbon tetrachloride are 360 and 99.8 00w}— Torr. respectively. at 296 K. What is the vapor pressure ofa solution containing 50.0 g of each compound? ~ 0 . 0 mg: (38 : 5.23,— : w : 52159-032 A) 260 Torr 3- "l L93 (my AM" ml MOI L' :543/ " a 274 tor « W6331 C) 241 Torr D)33.0Torr : 0%) €3.57» (3 '3; * E)460Torr Primal (0,93 3m + (033 9 K75 Ecru, 8. For dinitrogen monoxide. the arrangement ofthe atoms is N-N-O. One possible Lewis structure contains a double bond between N and N and another double bond between N and O. For this structure. the formal charges on N. N. and 0. respectively. are: $0. -1. r] -l. +l. 0 " ,__ __ " C)0.+l.-| NflNfl-O- 010.0.0 _{ H O E)-2.+l.+l 9. All ofthe following are paramagnetic except '9?” ? _____U-% ,_. mo; -—— a—vr‘k “We. 441* .———Tr* BB}: g: qizgk 5% Peter: 43:- 3+; It“ ‘2: qt“ ‘3}; 44:7... (3)05 4t: tr 4351‘s 4"“? 4E? 4"“ It D)O:_ mils Us 4;: a [503+ qtvk (Hf: «rte 4:: 59:: J‘Hr 4E1” 01” of O “L 2 (pl Ll —‘ 28 10. In the most plausible Lewis structure oerOFg. there are A) 2 single bonds. 1 double bond. and l lone pair of electrons around Xe. B) 3 single bonds and l lone pair ofelectrons around Xe. Cl 2 single bonds. 1 double bond. and 3 lone pair of electrons around Xe. a} 2 single bonds. 1 double bond. and 2 lonc pairs of electrons around Xe. ) 3 single bonds and 2 lone pairs ot'electrons around Xe. Foo l N1 lIC-Ix'i" firm l I I Page 5 of8 Print Name: z I C HE Maggy); r ich ofthe following species has bonds with the most ionic character? to: R Mew diff "m E“ B'jPClg, JGUIWS‘r 2e gig-38210 Gm W‘vgdic big—x E)NO~ 12. Which ofthe following can form intermolecular hydrogen bonds? A) CH3CH3CH3CH3CH3 m EN me+ B) CH3CH3CHO- 1+ m+ an O CHICH3COCH3—m Hr EM 0 (:H,(:H:NH2 amt) O‘VUL, WH‘lm ‘ E) CH;CH3CH3CH:CH; a m EN Law | r eta/unwel- H; _ g, N z ‘ H 13. Predict which ofthe following liquids has the lowest C(LrithalH’ ofva orization. A) H:Se n (9213+ wwgg B’H3O ' +0 boil Br @1142; “WC- btgcw macs ) 2 L 1'0 bOl'l ISO BWV H10 Pr “gm‘bi int law Shoulél have lower New}? c...— ) H S‘ m 8 LLP 1 TM uS‘ l 14. The mass ofa face-centered cubic unit cell is M“ V? oi’ 0:3th (1W A) Tuo times the mass ofone atom. I I B) Fm: times the mass ofonc atom. /8 ' 8.“ l W C) Equal to the mass ofone atom. : D} St); times the mass ofone atom. 6- am back l: 3101‘ ® Four times the mass ofone atom. l/IL- Ca —- 3 (Kim 1+ 3 I 4 WM [REM-h ofthc following would have the longestm .'- WW .' E’ ‘ _ 454°: n 45% +35: 3354: 443% 4.9V» 45 4+; ‘lt 11%: 4w ‘tt 3% *2. it}. 81 0; N2 (:2 N24 ~ —2 - E”; ii“ -2 r L: 30 firm 2 ‘ 1 © X973) 2 @ . lVl lIdl‘Q/{LM l Page 6 of8 Print Name: if E I: C HE; @2120}; 16. The vapor pressure of methanol at 25°C is 123 Torr and its enthalpy ofvaporization is 35.3 kJ'mol“. Estimate the normal boiling point of methanol. Assume the enthalpy of vaporization is independent oftemperarure. @ Solve”,- LN C, , _ AH _ ($333 $2 9 " C 0- M, an MSW/“4’ [‘7 ~1qu .- J m 3 u ' 331514 llfi‘fif’m.: Q. Q; a. r :34 D)373 K A 3 E) Not enough information given. C, r l- 9 95‘— V/Q fifth 1 ® d/wm k- .- a 7&0 {jive-L : [.3952x 10 5511 Q T : .3 Al I , to"? K 17. An animal cell assumes its normal volume when it is placed in a solution with a total solute molarity (molarity of nonelectroyltes plus ions) of0.3 m. Ifthe cell is placed in a solution with a total solute molarity of0.6 M. A) the escaping tendency (volatility) ofthe water in the solution increases B) no movement ofthe water takes place C) water enters the cell causing expansion D) the escaping tendency ofthc water in the cell decreases ® water leaves the cell causing contraction l8. Which ofthc following is true'.‘ A) Butane. C4H|t.. has a higher boiling point than acetone. CH3COCH3. Pentanc. OH”. has a higher boiling point than hexane. CfiHM. mam (2 CHgFg has a higher bmling point than CF4. ' 3 D) CH4 has a higher boiling point than ('04. W11, Di HI has a lower boiling point than HBr. Wm btgpfl'lM “mus mega bands pea/Lt. . 1_ l0. How many resonance structures are there for the carbonate anion, (COJT '? All A; 3 Bl: I. 182 24 (all; “9- “Z to}: Dl-‘3 _2 as /C\. 4'5 Q t. \ \O_ Mid RPM i r c: Page 7 of8 Print Name: it 555 ' 32:15” J 20. The phase diagram for a pure substance is given below E 0 rm 2m 300 am At 100 atm and 225 K, the substance exists as A} both vapor and liquid in equilibrium. @liquid both vapor and solid in equilibrium D) vapor E) solid 2] . The phase diagram for a pure substance is given below. The solid sublimes ID _| 250 “‘ am - , PrusureJtm l 1 15-0 -l ICU "I 50 —l.-—r___.—-- Vapor 0 me am am TmmK A) at 400 K and 200 atm B) at 200 K and 100 atm. C) at 300 K and 100 atm. ) at 300 K and 75 atm. ifwarmed at any pressure below 50 atm. MPICil’Q-fm I Pag680f 8 Print Name: lg E | CHE faill 2.035 22. The vapor pressure ofstrucrure l is lower than the vapor pressure ofstructure II due to H H Br H \C__ / \CzC/ \ / \ Br Br H Br I ll 25 . . Volumi Cal-4x“) 0on3 dipole-dipole forces 5 . London forces \fol : E g C. hydrogen bonding _ ’ 3 D. ion-ion forces E‘ 4 Y‘ to :3“ E. ion-dipole forces ,_ Zr , l —3 3 [O F E J r ‘ “0 0M x '2. 23. The density solid krypton is 2.16 g'cm'l. Ifkrypton crystallizes in a simple cubic structure. estimate the atomic radius. 1 [Ca 37%.} 3 ,2; “Mb @200pm .‘U‘CE lcflomxl kg 0113 pm 0-012“ “M m/ol/ D) 318 pm E)450pm Velma c—"—.' 2-1. The vapor pressure ofwatcr above 40mL of water in a lOOmL container is 23.8 Torr at imm 25°C. What is the vapor pressure ofthe water ifthe volume ofthe container is changed to 50 mL’.’ At about 25 Torr Pvap 100+ refilled) +0 Valeria/Lb D)-l7.6 Torr E) l 1.9 Torr 25. A 5.5(l-gram sample ofa compound as dissolved in 250. grams ofbcnzene. The freezing point ofthis solution is l.02°C below that ofpure benzene. What is the molar mass of this compound? (:N'nn’.‘ Kffor benzene = 5.l2°C/m.) A) 22.0 grmol ll0._!mo| AT : - "IVer G2 2 K4 220. g-mol Dl 4-4.0 g'mol 550 E] none ofthese (. Olocj : IZOC‘ J %4W . I I I 0.9.50k8 MW: no 3M0! ...
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