Chem 14 A Spring 2006 Midterm 1 and 2

Chem 14 A Spring 2006 Midterm 1 and 2 - Chemistry 14A-1 Dr....

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Unformatted text preview: Chemistry 14A-1 Dr. BR. Scerri Mid Term 1, Feb 2006 scored availabie - 14 :- Instructions: This exam has 4 questions including some multi-choice questions and a periodic table at end of exam. Verify you have the right number of pages before you begin. Write your name on each page. Raise your hand if you don‘t understand a question. SHOW YOUR WORK except for multiple choice! No credit will be given for an unsubstantiated or illegible answer. Write legibly, use proper units throughout and use significant figges in all answers. Good luck! Possibly useful information: 12 inches = 1 foot, 2.54 em = 1 inch. h = 6.63 x10-34 J sec N0 = 6.02 X1023 mol-1 0 = 3.00 x103 m sec-1 me: 9.11 x 1031 kg 1a.m.u. = 1.66 x 10-27 kg 1 Angstrom = 10-10111 g = 9.81 mfs 1eV = 1.602 x10'19J Velectrostatic(r) °C Qin/r; K.E. =1/2mv2 = p2/2m F = -AV/Ar 7w = c -‘ AB = Ef - E = 8mm: hv E = hvo + K.E = L _ h mv 21:] mAvAx—Apr 2 4n Probability density = prim? E. = —(2.18 x10'18 Jim/n2; En= -(2.18 x10"31)22(1/ni2- W) n—E-l spherical (radial) nodes; 6 planar nodes; n-l total nodes 1a. A compound X consisting of carbon, hydrogen and oxygen only is burned in oxygen. The products are carbon dioxide and water. Assume that the yield of these two compounds is 75% for each one and that 16.5 g of CO; and 10.125 9 of H20 are actually formed. Find the empirical formula of compound X. (8) (continue over page If necessary). [,4er at e ,, ,Wg/‘k! \ huh?)- filo 4 01-7 (024 #30 O l we“ a” 7f - 'é-S‘: “’6 l - foo - ac: dew“ ‘5 r50 ' 5 L’ 9 (r ~. we: m a a: 1 I? 9 (Q? A'ONAJU‘F "' l '3‘ 3 l4 1 10-h S ‘r ’00 2 H 0 :L'AE'Ja‘t‘ltt-I a L 9 " X __*\_#l' _ I . 9M?) 'g ' I‘: I.“ g “ LVQJ'D, H! H ,. Mn. wofifimr ‘ ()2'0' l 30,9 0 >v IMF _ «I; ‘1 _ a -- 1:6264 ‘ ' - ,, 5"on i ( W'O'fi 5‘3? ‘ 2'72 Ho XZ /( S $6.00.; 2", M H l 0‘? ( .4 -) l£.01 fl gruff” (Ylw‘i'mJ 1,9530 C E'H‘Efi'yo" / f +2-WWWO" ' 1a“, 7 - H 3 \fiy g 5-; w! —-'* 0% O T 4 9 3’“ 7 O yr ‘ -" 6 Ci- 7 l2 H30 5 What is the experimental evidence for light waves behaving a waves, “1 din/yr ‘r frfrrfajt In I; I; in; it’firafkh 51-6] i‘~}“.-!:P;?nf kk’tk Ar Hi; 05 ?/ V‘Qw f)- particles? ‘nr 1 L. /((}‘rf( WM ki,.g[,’( . if (V 2a. Sketch a graph of first ionization energies to show how this quantity varies from sodium to argon only. Explain the overall trend and the first anomaly (in terms of increasing Z). (3) 3 DE veal .1) {sum 9, .05; Mt 13,456! gammy? g)" a ,f ohm-ml ‘? fF£r(l‘l‘/f. 965 twin“) 0((y‘rf a»)? 41‘ pin},‘\ N W Chgijh 5. 2b. Write the full configuration for an atom of Bi (bismuth). Also give box diagram for all the electrons in the outer shell. (3) 3 {$1 le 2,135? EFé #512410 [-4205 5‘1 LIAM: TFL 6S1 63"} El Sol Bi 2c. Assume that an atom of silver (symbol Ag) behaves like an atom of chromium in giving an anomalous configuration. Write the abbreviated configuration for the A9 as well as the configuration for the Ag+1 ion. In both cases you may use noble gas core configurations as abbreviations. (6) Q 145’ UV] Ss'tial'o 14;”? [M w 3a. Sketch a graph to show a plot of (i) the probability amplitude or ‘P of a 25 orbital versus distance from the nucleus. (ii) 4 :m r2 W2 versus distance from nucleus also for a 25 orbital. » i 0 Mom (6) 5 3b. What are the total number of radi§| nodes from a_|l the orbitals in the third shell? A I 5 3 3 c Mi 1 r ——_-----Z--_c::£_/:’:~_I_ half! Z, (3) if i 3:. k 5 1 2 ‘2 “"(lri 34w“: 2 far/{qt hwl-Q 344:,” 34’s} 0 30. Sketch a graph of the velocityZOf ejected electrons as a function of frequency in a photoelectric experiment. Include any special features in your sketch. 2? My‘ (3) Qflmgfg I” 5"” P’V‘V 'L’bb 5 f 3L 2 f?! 1.8th - 30. Draw a 25 orbital in such asfarray as to show any nodes, radial or planar. Z! , \ Mia; mi: ‘ (2) C 366%? one Wad answer 61” (40469 4’11. In 13th5 atomic theory, when an electron moves from one energy level to another energy level more distant from the nucleus a) energy is emitted. @ energy is absorbed. c no change in energy occurs. d) light is emitted. e) none of these .......__._.._. Mm The number of unpaired electrons in the outer subshell of a Cl atom is a) 0 b 1 c) 2. d) 3. 9) none of these Which of the following indicates the ground-state electron configuration of Co? a) «'l 2252219“’3$23P‘"1 fl it Li J. _T_ _I_ 45 3d b) assesses} \T 1*. ii. 1%.. _T_ _T_ 74‘s? 3d d assesses} - ~ T_¢ :3 .73. fir; 4s 3d d) Ilszzszzpfisszspél 1 1r. 1 J: -T_ ._ 45 3d e) none of these [1)“ r} mullIwI||I|llfll|IH|Hg)IllIlllfl'llll||lg“lllplmlllllllellllllg/H“WWWIIIJ]IWWI“11mmIllmunpmmlWWHum. $039.... $33 Hfimzozamgm: @ mPUDn—OKL >hu<~Uwam __wflm.z§ fl ,. 3.5. , 32.2.5.5 31.55 :55 :52... $3”. 35.“: WE; m3 VA: A v mE<Z ._.I0_m>> U=20h< mmmED Z 2.20.? aOmE>m . . m m; a ., . . ‘ . 5.55 :55: Sean when . . 8.2 . 5.3. 5.9 m . h o O Z O o— 02 35 «S fix: Eng»: 86 m 9! SE mam—S. 0.00:5.— mI... S 25.2 1mm]lethnlmImfilmllmnlmlTlmmmWWIllmlmlIHITHIIIIMIIHIIWHHHHIM Chemistry 14A-1 Dr. E.R. Scerri Mid-term 2 Feb, 2006 PROBLE SCO POINTS M 1 _-l- .- 3 Name _ Instructions: This exam has 4 questions plus a periodic table at end of exam. Verify you have the right number of pages before you begin. Write your name on each page. Raise your hand if you don't understand a question. SHOW YOUR WORK! No credit will be given for an unsubstantiated or illegible answer. Write legibly, use proper units throughout and use significant figures in all answers. Good luck! ' Possibly useful information: 12 inches = 1 foot, 2.54 cm: 1 inch. h = 6.63 x 10-34 J sec N0 = 6.02 x 1023 11161-1 c z 3.00 X108 111 sec-1 me = 9.11 x 10-31 kg 1 a.m.u. = 1.66 x10-27 kgl A = 10-10m g = 9.81 m/s 16V=1.602X10h19J Velectrostaticu') °C QIQZ/r; K-E- =1/2mV2 2 pz/zm F : ~AV/Ar 2w = 0 AB = E - E = ephotonz hv hv = hvO + K. E.(e1ecr.ron) h h h Km“ 2 E =; mAvAx = Apr Z 1; Probability density = |‘i’n(r)|2 En = {2.18 x 10'18 mafia/112; rm: (0.529 Amazefi n—l—l spherical (radial) nodes; 1 angular nodes; n-l total nodes Bond order = (# bonding e- - # antibonding e-)/2 Emv = hvvibw + 1/2); v = 0,1,2... 1 k mlm2 Name a 1. Find the Lewis structure for the Sega molecule. (3) Ln) _2(fx6 1 lizard/.5 C J by! («12‘- :8}: (_ 39d Draw the 2 possible 3-dimensi0hal shapes for this molecule. (4) e a ‘3’" L 1157/ ’12. I; prises-ca, - 2);“: / \ t ‘r‘ ) Suggest n s to describe the atomic and electronic geometry for each structure (a total of 4 responses is required). Indicate these names next to your 2 structures above. (4) Do each of the H33 molecules have a net (permanent) dipole or not. Again indicate this next to each structure above. (2) Explain your responses in a general way. (2) 17%»): Ha 0“ air / [1 Name .—____ T E. 2. The nitrite ion N02' can be represented by a number of resonance forms. Draw them. (5) 11"" '3'" 6 1 2 goat/5 m6: H mm" .. u. .‘ fi -' 1,-7- [EQ‘NZGQ (’9 IQCE-Nv— g; 5 Explain why one of these alone does not provide an adequate description of the ion. (3) TL; Jan“... “flail 111...! Mt Lon/J “Iqu gm/ 0 «a 3 L '0 a. daULl-f low-d No If LHJ, I I Give a diagram Wthh goes beyond the Lew:s structure scheme and that shows just one structure for the ion. (2) 7 ‘ l 0 What is the bond order in the 022' ion? Show your working. (3) B How does the bond strength compare with that of 02 ? (2) O?" o' 03‘ - so: 12(6'4) = ’4 (8'6) :1 ,2 a $61,? 4 In t, i?” L , .. _ _, __ 7? BO 6: a. 2mm): 9202-4) 2 z 37‘?! LII—{r39 Clam? “i “4 LMDI u 022' '7‘" “4”” 1:6; _‘r_ P; LL“. +th 1.. (oz N ame ~ ‘ 3. The 002 and the 02H2 molecules both display the same hybridization on the carbon atoms. However, C02 has double bonds Lb whereas the other molecule has a ‘triple bond“ between the two carbon atoms. Draw labeled hybridization diagrams to show ALL bonds in BOTH molecules. We / Which if any of these molecules has a net dipole? Explain briefly. 3 (10 Nfll’l‘fv 0L 1"!!! N/Pfuf’l LR} ( ) ‘\ l “I Ohio]; beta-rs? lth olIPalrr mud (Du/t Erma: $.11. haiku}; R-r lumr lied mr‘f i ’ 9’0” ‘J‘pdffi j” 1'4 ’r""‘f"r 0‘ (~er M’Irb’f Fit-Ir} l'L‘H ‘1; (nm((‘ ld Name — 4. Devise a suitable rule for the third period diatomic molecules by analogy with the Z average 2 8 rule which applies to the order of energy levels for second period diatomic molecules. (3) 3 .F— E Z 16 H“ 6 Law/t wt luv-Iv h" ‘4'“ L‘Wl/‘l Use your new rule to draw the molecular orbital diagram for the PS diatomic molecule. Show all outer-shell electrons for both atoms. Assume there are no ‘non-bonding electrons’. (5) 5 ' ? 0W} ': K? r PS 6...??? 5* What magnetic properties, if any, does the molecule have? (2) Z Explain briefly. Park P‘G-‘h‘pi‘lt beo-‘H Hut U cm s“I’I'l‘ull'l‘rl smamam uomsucu, ...
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This test prep was uploaded on 02/21/2008 for the course CHEM 14A taught by Professor Scerri during the Spring '06 term at UCLA.

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Chem 14 A Spring 2006 Midterm 1 and 2 - Chemistry 14A-1 Dr....

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