142exam_answers_Exam_2_Vers_A

142exam_answers_Exam_2_Vers_A - CHEMISTRY 120A HOUR EXAM II...

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Unformatted text preview: CHEMISTRY 120A HOUR EXAM II (Version A) Autumn 2007 . Tuesday, November 20, 2007 ~Name: a TA Section: Student Number: I TA Name: Score (pg) 1 GOOD LUCK! Watch the sig figs, and units 3 SHOW YOUR WORK! 2 - . Total (x/100) PV = nRT STP (273K, 1.00 atm) ' 1 atm = 760 mm Hg P1V1/(T1) = P2V2/(T2) Na = 6.02 x 1023 - calorie = 4.184 J Percent yield = (actual yield/(theoretical yield)) x 100% ' P = F/A . K % °C + 273 ' "F = (9/5) °C + 32 R = 0.0821 L*atm/(mole*K) PL = P1 + P2 + P3 + .... .. Heat=(mass)*(SH)*AT Aern = H(produc‘ts)-IH(reactants)' at constantP I. DEFINITIONS (10 pts): Define any five (5) of the' following terms . in the con ext 0 this course: ~ ) *electronegativity 7/76! .w/o 252/: 9 x/,’ a; h mém 3-,, c, c/Em/ba/ Aura} I f9 QAO/flf 8,” ‘b’ £34511: _ , f ’ *oxidation vs reduction GXI'6/9’7é'0k /'§ [453* a/Pl rfa/“C' 0"- l‘fi"”~' " e * '4 fl I 1571M!” fl:- fb/Kk/ /or/ W hYdrogen it)": :wt/efu/j 4; fl: [0,; ,,N) egg“, y Mc/t’cy/(, _ *specific heat Z‘hqné' a; zfg/mff/g/ warm /)/9>u c/ a) 5'94; hr? 57 /"’C l - fl ,4 *VSEPR VQ/Wre £4?” [/cC/‘m 39/1 167/952? (or) r .— Fwd/b5") 5/53)“ apt/'ry/r’zflzo 1"" Fir *activation energy 979919;, Ma ,W/a Area / mtg/40;; “‘4 M/rce/s, 214/ 2'4 ’5"; oW/Cfi _ ’5. 19' I *dipole 55.94.,ch offer/7;?) #0,“ W99 :29 r r}: /k I I q bade/Z mgfm/{eal /' a’v Hsrahc *"' ' zo/ 01/6/11761/ _ boulmg pomt 7:22:29 W :X4yn2//N5_'§ tag/GA), /,9,,,g79 fig,- 0y I. o % *sublimation Sci /’?"’d 9”” ,\/>/\45r (49,55 70% Sa/f/ o/z'Nc// 7'4 chr é: £o/%aé/ 96/75 flrohfx //’9L,/'/// ;(_ ll. CONCEPTUAL, SHORT ANSWER ( subtotal = 42 pts) {6) _ 1. Give the strongest attractive force or bonding type for each of the following: (a) He atoms in liquid He _ oégyppry/m (b) H20 molecules in liquid-H20 é/JWO/i’V7 (c) CHgBl' molecules in liquid CHaBr dye/(479094 (d) between H and F atoms in a molecule of HF /"/"’ ‘0”9/“Vl (e) between Na+ and" Cl ‘ in a crystal of NaCl /'0’7/‘C (f) between H and in'a molecule of H2 hW-Fe/GV C 9991’”); _ i (4) _ _ 2. Draw electron dot formulas for each of the following species; (a) .CBr4 (b) HCCH (0) C32 (d) PBr3 ’ ‘34" -. I _, =- .. H :C :g —- r 4 C’ C a / s -’ .41 "345 3. Draw two equivalent resonance structures for ozone (03) 'r 1‘ ' J Z 5.0.] . * '0 (3) -4. In a system of cooling water. and ice at the freezing point, why does the r temperature remain constant until all the water is frozen? )7, 751'94223‘} tug/4‘17 Ire M/taxfc A 74,9.“4 ) pwmikj Ararr Coo/x'Tj G// MAW b91412)" Arcana" fr? . (a a, (g) 5. For each of the following phase transitions, name the appropriate heat (a) liquid to gas: .AH( l12£°rff9ék/oy ,Cm/&-ra7{‘a~ (b) solid to liquid AH( ate/74‘ or new (0) solid to gas AH( rel/I’m»!me dyes/3‘61“, (3) (3) l2) (3) 6. For the reaction A9 B, indicate on the graph the magnitudes of the heat of reaction Aern and the activation energy Eacg Is this reaction endothermic or exothermic? .7. Gas laws: complete the following: r x” Farm/5 __,, _ (a) For constant (n,T)', Pis proportional to '/M (b) For constant (n,V)‘, Pis proportional to_ T _—~ (c) For constant (n,P), V is proportional to I 8. Name both the VSEPR configuration and the molecular shape'for each of the following: ,CH4 H28 BeHz 502 ' pF3 VS EP R . ¢¢°749 4 “(m I #5"; [to], If” ea I 710,333; I 7/009 A J“: / Molec. shape 7999/7 far/VD / b M74 lx'tvca V j{,,/ /-r lama/ 'pyn Mt'o’c-i 9. Which phase of matter (solid, liquid, gas) has: (a) fixedshape and volume S'a/z’a’ ' -(b) fixed volume but not shape Aim-g 10. Kinetic theory of gases for an ideal atomic gas F (a) (TB all atoms travel at the same speed for a given gas temperature. 7' - (b) CDF) the atoms in the gas have negligible volume themselves. F (0) (TE attractive forces between the atoms in a gas hold it together. 11. In the following redox reaction, indicate both the species undergoing reduction and the species undergoing oxidation. Balance the reaction. 3 Fe +302 9 F6304 — 75 It flea/med o XIV/7W 5; (€709 _ P 4.734 f .K '7’; lll. QUANTITATIVE ( 12 pts each, subtotal = 48 pts) 1. Carbon disulfide is produced by the reaction of carbon and sulfur dioxide: 5 C (s) + 2 802 (g) 9 032 (9) + 4 00(9) What is the perCent yield for this reaction if 40.0 g of carbon produces 36.0 g of carbon disulfide? . l 9/: moo/e (ya/775.2565; (4O DEM gage) (jam/e C l we (is; git/t)” gaggax/CU); 35.70. 3535 7'47; - 2. Using the heat of vaporization ( 54,0 cal/g ), and the specific heat of water . (1.00 cal/(g °C ), calculate the amount of heat released (in calories) when 125 g of steam at 100 °C is condensed and the resulting liquid water cooled to 15 °C. ' E'VIIL CWO/WS‘C Q /cvoc (/253J{§:0\cq/) : /aa°c 6/0””) A /§‘°c A7:,85'°c q 3 6.8 X/0 m 5775 X/O Ce/ 0" /- re/ft .7] 22!?» Coc/ fir 'ouwlfr ./,25‘ /.oo cq/ ark : 10.6 XM a! w I.) X/o pea/a ( sari” )( > ‘ _ _ WM \ ' 7374/ N/quea’ {ea/(J) 4/{eg/KJ) I / _, I, d-é’X/O’ég/ 4 /./’/\’/0 Cal 4 . : 67,9)00 Col} 2 or 3 rggs; o’/< - .— .60 (fry/9 6168 ,- ' .2/0 .0‘, — \ Sig-figs 3. »The formation of rust (Fe203) {mm the reaction cf solid iron with oxygen gas releases 1.7 x103 Kim- 4 Fe (5) + 3 02 (g) a 2 Fe203(s) AH = -1.7 x103 mama How many kJ of heat are released when 2.00 g of Fe react with excess oxygen? . g 3 [3. 009){//ma/f/E)' {3. 8 3 9%!” mm KW ww— grxj/CS; _OVZZ'_$—/X/_—0E:V“ 4. How many moles of Al203 are produced when 20.0 g of Al metal and 20.0 g of 02 gas react by the following reaction? Indicate the limiting reactant. - _ 4 Al (3) + 3 02 (g) —> . 2‘AI203 (s) f) 57/9/45} . ' ./ a}: 79/ Mac/rs fl/é} ( / . a/ m 2 2 3 , Aw/ fl 0 [&)(29'ofifll) 40am?! )9/ fPQJZC‘Mz 3 I 7cm 70-03 4?: ‘0/7’52 Awe/1'5 lg}: 03 I ‘- freo’hcm/ 2&0} a: 4 M3 a’c‘we Sign) ; MI; 02,. v §a 19/ /S //?n/'/§‘I”) 73°53” ‘ J ./ (WW—’45? (2W ”’ a j ,2 «v1 add/Kn -\ not in ‘cai-‘mfi \im‘tfih '—:2. giving 3 am: 3 pie. %r fining. ...
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142exam_answers_Exam_2_Vers_A - CHEMISTRY 120A HOUR EXAM II...

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