105af06_e3_key

105af06_e3_key - Chem 105a Exam 3 Last First Initial...

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Unformatted text preview: Chem 105a Exam 3 Last First Initial Thursday, October 26, 2006 Last 4 digits Student ID # _ _ _ _ Professor Stephens Lab TA's Name Lab Day & time: Major Questions Points Score Grader 8 10 4 l l 4 12 6 Total 100 -) Please Sign Below I certify that I have observed all the rules of Academic Integrity While taking this examination. Signature: INSTRUCTIONS 1. You must show your work to receive credit. 2. If necessary, please continue your solutions on the back of the preceding page (facing you). 3. YOU MUST Use non—erasable ink. 4. There are 12 problems on 14 pages. PleaSe count them before you begin. l. (8 pts.) The overall reaction in a commercial heat pack can be represented as 4Fe(s) + 302(g) -) 2Fe203(s) AH = —l652kJ a) How much heat is released when 4.00 mol iron is reacted with excess 03? CL = lbfz k7 $2LJ¢V MlWS/uid‘hb. b) How much heat is released when 1.00 mol Fe203 is produced? (1’ '—2’ c) How much heat is released when 1.00g iron is reacted with excess 02 ? kwbj-FQ = ‘2 = 0.0V?“ M\\Qs 5519f CL: l§§§*o.m1q = 73‘] 0' d) How much heat is released when 10.0g Fe and 2.00 g 02 are reacted? fir— 23 OZ —- 2- ; OQ‘QZ(W~JLI¢9 Oz 32.x: -‘. Oz \5 LuMV'hN'Z‘ QEAQTA-NT. 0.0675 “Aon G; —> “hauoszf k7 2. (8 pts.)The enthalpy of combustion of solid carbon to form carbon dioxide is —393.7 kJ/mol carbon, and the enthalpy of combustion of carbon monoxide to form carbon dioxide is — 283.3kJ/mol CO. Use these data to calculate AH for the reaction 2cm + 03(g) a 2C0(g) C(5)+ 02033 ——> (02(3) bu;—333.7(CJ C005” 502(9) —-> (01(5) bus-23mm ZCOH 202m —> 2mm» emu—3cm Zcuzm —>ZCO(c,) + 0am) INA =2.<+233.3 JIM Zc(:) 4431(9) a 2mm) 0“ 2: 2*L’gfii7) + ZxQ-ZBKJ) = - 220.3 hf _________________._.__.—- Ix) 3. (8 pts.) Given the following data 2C1F(g) + 03(g) —> Cl30(g) + 1:30ng AH = 167.4kJ 2C1F3(g) +203(g) —> ClgO(g) + 3F:O(g) AH = 341.4kJ 2F3(g) + 03(g) —> 2F;O(g) AH = —43.4k‘| Calculate AH for the reaction ClF(g) + F3(g) —) ClF3(g) (Him +1 02010 9 £sz (9) + 53mm DH: l “ah-'47. lw’plcfl + 3 F250” a Q“:3 (‘5) *sznn ADJ-32L“ 2 L 2 F210“ *' 3&0;qu —> FLOOD ()9; Ag; 4. (5 pts) The standard enthalpy of combustion of ethylene gas, C73H4(g), is —141 1.1 kJ/mol at 298 K. Given the following enthalpies of formation, calculate AH? for C3H4(g). C03(g) —393.51<J/Inol 1130(1) —285.8 kJ/mol C2M3VZQL(Sl-—> Zcozo’i) “‘ 21120“) A“; —-N.\\ 1LT [WL‘UL CL‘H- DH : a A“; ((0,) + L b\-\¥(\-\zb) -— 01-14 (clung '-'- 2,; ’3q3,{ 4. 2 sl _' = -\\t.\\ . = $1.3 MM— 5. (8 pts.) The elements Si. Ga. As, Ge, Al, Cd, S, and Se are all used in the manufacture of various semiconduetor devices. Write the expected electron eonfiguratitm for each of these atoms. 3’; lszZrZZPQQZZVQ’ W [Na] 75239,— Gq \SZZSZZ?Q?523PQ WjdeNQ'?! o ‘ w [NJWSZNU L"? A; [A4 mzfd‘Wv? (ta [Av] M‘ZC’NWL M [N2] ?5 15H CdL [Kr] 351A“) 6. (7pts.) Write the electron configurations for a) the cations Mg'+. K+, and Al3+ M324- szszz?‘° U ls‘Zf‘ 29‘35139g Ax“ WZVZ?" b) the unions N37. 02’. F} and T627. 6 7. (9 pts.) Write the Lewis structures for each of the following molecules. Except for HCN and HgCO, the first atom listed is the central atom. For HCN and HgCO, carbon is the central atom. Usc circles to show all electrons; do not replace electrons by lines; cg. H3 is HzH, NOT H-H. a) HCN b) PH} c) CHCl; d) NH4l Problem 7 continued... C) HQCC) f) ScF; 2) CO: 11) O; 1) H81 HO F:SQ‘-$ 8. ( I2 pls.) Write Lcwis structures for the following ions and molecules. Show all resonance structui‘cs where applicable. a) NO} . NO; . N jO4 (N304 exists as OgN——N03). “:3”: *9 ‘6‘N339. :BzcztzN] H [9“C‘“‘.\ll 4—9 gozzzczN: e w. 6—) [:S‘u‘lC‘l‘i‘: - 0° ; Nti:N'.X <——> KiltNiiN 4' 9. (2] p15.) Write Lewis structures for the following species. Assign the formal charge for each cenlrzil atom. a) POCl} Ix.) l b) 804 e) 00} Ll) P04 e) SOgClg :5: :@:?‘oCE; 1° R: 5‘ixg‘tl- LES}: @2836}: :0 00 o. 6‘ o o a :O - - » no 00 °° 2-— sc<= G~ifl= t3; Problem 9 continued... g) CIO; ’— a9 w .. Q 39:89:19,: CL ‘CC: :0: l l l0. (4 pts.) The brilliant red color of fireworks is due to emission 01‘ light of wavelength 650nm when salts ol‘ Sr such as Sl‘(NO\)3 and SrCO; are heated. Calculate the frequency 01' the red light. [c=3.0 x 10“ m/secl i A w -u ‘1 '7) = 10“ _ 4“Ol,( JQC ’___________.__.————- - r- Q’" M “0“ “AL 12 l l. (4 pts.) The blue color of fireworks is due to emission of light of wavelength 450nm when Cum salts such 11s CuCl are heated. Calculate the energy of a photon 01‘ blue light. [c230 x 10h m/sec: h: 6626 x l()"‘4 .loule~scc.] [£sz 7) =C/x , -°l lx‘A-B’Onwx: q'bostlg m N 3 v = 3.0’<\D g H”; ‘ .. w E = (0.63% no: >< (mt-W“) ._\ ’ 44x4 KUS q J /__________ \P ll 13 ll. ((3 pls.) Arrange the following groups of atoms inorder of increasing size. a) Tc. S. Sc S<SK<Tx h) K. Br. Ni c) Bu, Si. F F<5iéga | 4 ...
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This note was uploaded on 10/26/2008 for the course CHEM 105ALg taught by Professor Bau during the Fall '07 term at USC.

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105af06_e3_key - Chem 105a Exam 3 Last First Initial...

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