Prelim 1 answers - (Last) (First) Cornell Student ID Number...

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Unformatted text preview: (Last) (First) Cornell Student ID Number Lab Instructor’s Name Lab Section (Day and Time) —-—-—__,__—____ Chemistry 207 Preliminary Examination 1 October 5, 2006 Time: 7:30 PM — 9:00 PM Please do not open the exam until told to do so. You have 1.5 hours to complete the exam. This exam has 9 pages, none of them blank. Page 9 shows a periodic table and various constants and equations. Before beginning work, check to make sure your exam is complete. Write directly on these pages. Show all of your work and indicate units where necessary. You may turn in the exam at the front of the room when finished. 1. (20) __ 2. (30) _,____ 3. (30) __ 4. (30) __ 5. (35) ___ 6- (30) __ TOTAL (175) 1. Briefly state the single most important fact or principle that was established by each of the following experiments. Each answer must be less than 20 words. [5pm] (a) Analysis of the wavelengths of light emitted by solids at various temperatures L‘t'alfi- an «(Jr as a. kegm 3Q par-locle I Ca (J4 wiM-x encer E : l0). [5pts] (b) Rutherford's irradiation of metal foil with alpha particles POSHRV‘ thwart, in 44M. ad‘m is Cohcen’bnkJ IA at \mcss‘nve hum-Jews. [5pm] (c) Thomson's measurements of cathode rays May‘, mks” “ca‘wdw LL‘ArocA par licks '1.th c.\\¢J e,\ccA-rd'hs. "new Glut-3,; /w1o\_55 FK‘H‘ was mgrtsqrecl. [5pts] ((1) Millikan's measurements with oil drops CLH’Jac on elccbrd'h we) MCASHIQJ. 2. The combustion of ammonia, NHB, produces only NO and water. 7.41g of 02 are combined with 5.23g NHS, and the reaction proceeds. What mass of NO is produced? NH3 1" SL101. 4M0 + %HLO Hun—13 sS‘ol -—-"> H‘Uo + CHLC) '1.‘i\a 0,. 2 \o, 231 Ma 0L 32.0"» 3M0\" §c23faNH3 __ 0.301Mu NH;s \____,_____.__._._ - 13.030Molfl 4min NH3 rowan; firs (“a wiA’L k“ 01) . a, 0.23Lm\ ox (“4 m1 Wad ‘ O.\‘3qu\ W3 < 03G ‘- Ma‘ NH: S—M-i 0p Moi €Mii 01.. 3. [5pts] (a) Rank the following by atomic radius, from smallest to largest: Sr, N, Li, Na. M<LL<NA<Sr [5pts] (b) Rank the following by ionic radius, from smallest to largest: P‘, K”, Cl‘, Ca2+. kl} < < C1- < ‘33..— [5pts] (c)Rank the following by first ionization energy, from lowest to highest: S, CI, Se, Ca. CA<SQ<S<Cl [15pm] (d) Give electron configurations for the following species. Use notation that abbreviates the noble gas electron configurations, and does not show spins explicitly. Sn {kt} Lu” 53‘ Sr‘ Ag CKrBLlA‘oS-«Si Ni2+ olg 4. [6pts] (3) A quantum mechanical particle moves on a line of length d. Its energy has the third lowest allowed value: only 2 lower energies are possible. Sketch a plot of the wavefunction along the line. (3‘) [6pts] (b) What is the wavelength of the wave you drew in (a)? Z l = /3 J [6pm] (c) For the particle in (a), sketch the probability for the particle's location along the line. w L W [6pts] ((1) Draw a cross—section of a surface of constant probability for a 3de orbital. Identify and label all nodes, and indicate the sign of the orbital at each point in space. E: k. “all. [612:3] (e) Identify all nodes of a 4py orbital. Draw one sketch of these nodes that shows their shapes, and their locations relative to the nucleus and to each other. it “WAG 2': h —l :: 3 # «Ana‘sf H0415 -: -Q = 1 fl: (ILA “MAL; _-_ Y\-.,Q-| :: Z "‘ 5. A compound contains only the atoms C,H,O, and S. [25pts] (3) The combustion of 5.00 g of compound produces 4.83 g C02, 1.48g H20, and 3.52g 802. What is the empirical formula of this compound? L133 5 Cohwfi lmd CWCZAH 3C) -_- Limo! 3m rm‘ (01— M61 C ('10? 3 Ma \" Mal 5‘51, Mal 5 Mass 0 '3 5.673 - Lil- 0.1“. - Llfi 3 =\l«}59'01 A Molzj C : 1.32.? 2 0. HQ Mo\ C- l’L,oU 3 Ni” MDLCJ H: OwlLC') -: H ‘.n'fal'u"‘ Mole) S 1' 1'}‘35 :- (5.05“-I‘1 M018 3L9}3M¢i"| Male; 0 ‘-’ l‘q'CQO : 0.lo“\ Mai O [6.00 ghol" 5. [IOpts] (b) The compound whose empirical formula you determined on the previous page is called Y. Compound Y reacts with aqueous sodium hydroxide to produce water and a product called Z, according to the balanced equation, 2NaOH(aq) + Y —» 2H20(l) + Z(aq). 5.00 g of compound Y and 27.5 mL of 2.00 M NaOH(aq) react completely, with neither material left over. What is the molecular formula of Y? ML “lug”. (2.0a Ma‘ Inch] ( MAM} \f \ \mHL L Lmfl MAO“ = 03.07.43“ Md Yl Mo\«r Mas: Y = 5.6%?) r 0.02.1}S'mol .r‘ '(‘DFMUAA ngJ «L Qhfitflgad Bruno-‘4 2’. ZLHA r?) +LHC) +323 M ‘H haul" \ 6. [20pm] (a) An atom of hydrogen can emit light in a process that leaves the electron in its lowest energy state. The longest wavelength of light that can be emitted in such a process is called 7&3, and the next longest possible wavelength is called 7th. Calculate 7th. n=3 EJ'EI = ‘15-. 3H, -‘- .5}... 02?. L Ea ~£I )0». >5 Eh: vzkku Fur 'H/ &:1. - 17 fl'\ Es'El: RH (l-—‘/1\ : 3R“ [0‘ ‘9 : lg/‘I (Z-laflKloJ‘T] '2. Lila-M! ‘3- )5 ’- (C-ClCKIO"3H)(Z.117Kl°9)m : \Lozcacm‘qu I 1.4m Mo“? :- Im.(. mm [IOpts] (b) The first ionization energy of one atom of Na is 8.233 x 10“9 J. Use this number to calculate the effective nuclear charge experienced by the highest energy electron in Na. “ru- imiz—d‘im Process Pam-th 35 Eli {vim Ufi< L $4; Meryl F's ‘PP’Miwkh En ~2<1+ [2H m; “:3. 1‘ I‘ :— 2“ RH 25H : .Iqi : ‘It3a133filo'm\ :_ Shy-x4 > RH Zol’r‘tmr" Comma—14‘. :4, A». (are. {'5 Agree-«:1 Ax VHchv blurb!— YJNQQLJAS ) Mam :1" 2 "’H (Are 2,.” 7- \‘-\C5'=»l- fl/flq C&\C~\\g)§nfl ,3ka An} A; ("I 1' rind)- Scrub—s ...
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Prelim 1 answers - (Last) (First) Cornell Student ID Number...

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