Exam 2 Fall 2004

Exam 2 Fall 2004 - ——————_—_——j...

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Unformatted text preview: ——————_—_——j r______.____— Chemistry 105a, First letter of PLEASE PRINT YOUR NAME IN BLOCK LETTERS last name Fall, 2004 Name: Exam #2 Oct 7, 2004 rLast 4 digits of S.I.D.: Dr. Robert Bau T.A.'s Name: Lab: (M aft. / M eve. / Tu morn. / Tu aft. / W aft. / Th morn. / F aft. / none) (please circle lab section above) Question Maximum Score Grader points 3 1 10 r 2 24 Mfr» e7{ 3 k 10 r 4 10 4257 * T 5 L 14 6 16 7 J 16 H Total ; 100 I VIII 1 2 H II III IV V VI VII He 1.00797 4.00260 3 4 1 5 l 6 7 8 ‘ 9 10 Li Be B C N O F Ne 6.941 9.01218 10.811 12.0111 ‘14.0067 F15.9994 18.9984 20.1794 11 12 ‘ 13 "l 14 15 16 1 17—] 18 Na Mg A1 Si P 5 Cl Ar 22.9897 24.305 . 26.9815 28.086 30.9737 32.064 J 35.453 39.948 J 19 20 21 22 23 24 l 25 26 27 28 29 30 31 r 32 r 33 34 35 36 1 | K Ca Sc Ti V Cr Mn Fe Co Ni Cu IZn Ga Ge As Se Br Kr 39.0983 40.08 44.9559 47.90 50.941 4 51.996 54.9380 55.847 98.9332 58.69 63.546 |65.377 69.72 72.59 74921617836 179.904 83.80 37 l 38 l 39 40 41 42 43 1 44 45 47 49 1 50 ' 46 48 51 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd [Ag Cd In Sn Sb Te 1 Xe 1 85.467 87.62 88.9059_+ 91.22 92.9064 F 95.94 98.9062 101.07 102.905 F 106.4 107.868 ' 112.40 114.82 J 118.69 L 121.75 L12260 126904 131.30 F' 55 , 56 57 v 72 T 73 74 75 76 77 7s 79 80 81 82 83 84 T 85 86 1 l 6 Cs Ba La Hf Ta W Re Os Ir Pt ' Au Hg T1 Pb Bl Po At Rn 132.905_T137.34 138.905 178.49 180.948 183.85 186.2 L 190.2 P1922 195.09 196.966 1 200.59 J 204.38 207.19 ‘203980 1 1209) , (210 (222) 87 88 89 1 104 105 106 107 108 ' 109 Fr Ra Ac (223) 226.025 227.027 " T 58 59 6o 61 62 63 64 I 65 l 66 67 68 1 69 I 70 71 ‘ Lanthanides Ce Pr Nd Pm Sm Eu Gd I Tb Dy Ho Er Tm Yb Lu l H140.12 J40.907 144.24 +150.35 151.96 137.25 [158.925 162.50 + 164.930 L 167.26 168.934 173.04 174.97 1 90 91 92 93 94 95 96 97 i 98 99 100 101 102 103 Acfinides Th Pa U . Np Pu Am Cm Bk c1 Es lFm lMd 1 No ‘Lw 232.038 231.035 238.029 237.048 (244) (243) (247) __L_ (247) L (251) (252) 1 (257) I (258) l (259) I have observed all the rules of academic integrity while taking this exam signature Question 1 (10 pts) CIRCLE CORRECT ANSWERS (a) For the reaction Ba(N03)2 (aq) + K2504(aq) -—+ 32604 (s) + 2KN03 (aq), the spectator ions are: (i) Ba+(aq) and N03‘(aq) (v) Ba2+(aq) and N03'(aq) (ii) Ba+(aq) and SO4'(aq) (vi) Ba2+(aq) and SO42‘(aq) iii K+(aq) and SO4‘(aq) (vii) K+(aq) and SO42‘(aq) /,.~,+(aq) and NO3'(aq) (viii) K2+(aq) and N03‘(aq) (ix) none of the above (b) For the reaction in part (a), the net ionic equation is: i Ba+ (aq) + 504' (aq) —> BaSO4 (s) y”? (5} Ba” (aq) + 5042‘ (aq) —> BaSO4 (5) (iii) K+ (aq) + NOg' (aq) —> KN03 (aq) (iv) Ba(NO3)2 (aq) + K2504 (aq) ——> 321804 (5) + 2K+(aq) + 2N03’(aq) (V) Ba+ (aq) + 2NO3" (aq) + 2K+ (aq) + 804‘ (aq) —> BaSO4 (s) + 2 KN03 (aq) (vi) Ba2+ (aq) + 2N03‘ (aq) + 2K+ (aq) + 8042‘ (aq) —) BaSO4 (s) + 2 KN03 (aq) (vii) none of the above (c) For the reaction A1(OH)3 (s) + 3 HN03 (aq) ——> A1(NO3)3 (aq) + 3 H20 (1), the spectator ions are: (i) H+(aq) and OH‘(aq) (vi) A1+ (aq) only (ii) Al+(aq) + N03'(aq) (vii Al3+ a) only (iii) A13+ (aq) + NO3‘ (aq) (viii) N03" (aq) only "J (iv) H+(aq) only (ix none 0 t e above (v) OH‘(aq) only (d) When Pb(N03)2(aq) and KI(aq) are mixed, the net ionic equation is (i) Pb+(aq) + I‘(aq) —> PbI(s) -— Pb2+(aq) + 21-(aq) —-> Pb12(s) (iii) Pb2+(aq) + 12'(aq) —> PbI(s) (iv) K+(aq) + N03‘(aq) —> KNO3(s) (v) K+(aq) + N03'(aq) —> KN03(aq) (vi) none of the above (e) When NaZSO4 (aq) and K3PO4 (aq) are mixed, the net ionic equation is (i) Na+ (aq) + PO4' (aq) —«> NaPO4 (5) (ii) Na+ (aq) + PO43‘ (aq) ——> Na3P04 (s) (in) I<+ (aq) + 504- (aq) a 1604 (s) (iv) K+ a ) + 5042’ (aq) —) K2804 (s) ../z;> V) none of the above ) (m, Ram—l .N) Question #2 (24 pts) (a) (8 pts) What element gets oxidized or reduced in the following reaction? (Fill in the blanks 4" 4 A 7 1 *1 " l o :41" j ‘ 1' ’ Z or circle correct answers) MnOz + 4 Hél —> (E12 + MnClz + 2 H26 | element ox. number ox. number C2 is oxidized from "‘ l to 0 N m is reduced from + 4- to + Z The oxidizing agent is (Mn/ 0/ H / c1 HCI / C12 / MnClz / H20) The reducing agent is (Mn / O / H / C1 / MnOz @ C12 / MnC12 / H20) (b) Balance the following oxidation-reduction equation: ll [Cr207]2— + 12 —> Cr+3 + [103]- l (16pts) Note: you can do this question either in acidic or basic conditions (just choose one). 2— , +3 - r eno7 + iL —-¢ a.» 4- [L03] / l / / / t +6 ‘2 0 4—3 +5 ‘1 ox: I (o) -—9 I(H-) +se‘ >13 red: Cv(+6) +2414) Cr(+?) ~— 3(01) .- 31(0) 6 210:) 4» Ire” (“5 5M4): 5Cr<+6)+/se*-4 fat/(+3) K 0.0%: Ecru-0+ ?I(o)—9icr(+3)+3r(+s) fwt:/»‘h+<= 571 C"2 ‘’72- t 3/2. 12 ’9 55'” "L 3:03— . 1— .. 3+ ._ 2x1 Valium/4. fraw4n-n 5 CV107 +- 3.12 "9 (UCr 4- 6I03 ‘\ . . I ‘21 add: (“44". Lint-filth) 4— 2" + 3’9— _ .— aeu H 4-. sum“ 54447.44: 5CY207 + 3’12 +3‘I-H v—’> IOCr + $1.03 add Hg’: +. bald-u. H‘s -' icy; a," + 31L + 34H*—a may” + 6103' + nude If (A. base: (Alumna) - — ? ._ add or A balm“: *Wf“? 5 ("41672 + BIL —-9 locv ++ 67.0; + Zeou’ 2-— - 3 __ —- - 4U 49': 1“ (“MM “"3 50107 + 31.14» {71420 .9 (UCv ++ €1.03 1- ale-0H WM @estion #3 (10 pts) What volume of 1.25 M HCl will it take to react with twelve grams of Al(OH)3? 3964 + MCOH)] a ma} + 3HLO (/1 MOM) / "w" aw”): flaw/e; ace 2 3 z 0' 4‘62 m/Jq 1,51 7‘9; 4" (0’03 / not; (dam); V nuns 0.962 Mo,“- : : -~————-——-——————-——' 2 a.) I ("Hc‘h‘d'h /. 2‘5; 7 54“, Qgestion #4 (10 pts) A sealed balloon is filled with 0.75 liters of helium as at 23°C and 0.98 atm. The balloon rises to a point in the atmosphere when the ressure is 2 8 torr and the temperature is -39°C. What is the new volume of the balloon. ’a/VI _ szz T, 7; 24-; (0.654%)(0751) , ( /75° 0”“)(Vz) (273+22)/< (272—37)/< [a.9€a&.)(a-7J’L)(2?‘/I<) ll2 : (0-39’a/v)( 2‘76 k) : /' 7/ 1.31441 Question #5 (14 pts) (a) (10 pts) The rate of effusion of a particular gas was measured and found to be 59.8 mL/ min. Under the same conditions, the rate of effusion for xenon gas (Xe) is 47.8 mL/ min. What is the molar mass (molecular weight) of the unknown gas? __.._. “(M'h‘wu‘d (54(K1mm) M(X£non) M(kukMOWu) L&(x.£mov\) z M (uukhaum) :‘ [14(Mluou) K ) “(unknown L : [31-35/Wou x [ 47'? ML/W:“Z I558 mL/MIH 3(131-3>(O~8)2 = Z/WOIL (b) (2 pts). If the unknown gas is one of the following noble gases, which one is it? helium neon argon @ radon .\ \ (c). (2 pts) (Circle correct answer) There are certain situations when the Ideal Gas Law, PV=nRT, does not work. In these situations, a different formula called the van der Waals equation, [P + (nza/ V2)](V — nb) = nRT, is used instead. When does this happen? (i) at very low temperatures, like -100°C ~~~>@at extremely high pressures and small volumes (iii) at extremely low pressures and large volumes (like in outer space) (iv) when the gas is generated at highly acidic conditions (v) none of the above (in other words, the ideal gas law always works). mestion #6 (16 pts) When 300 mL of 0.200 M NaOH and 100 mL of 0.400 M HCl are mixed, what are the final concentrations of the ions H+, OH‘, Na+ and Cl' ? Natal! ,t Ha —-—” NA.“ #— (Ila mu“ Nam = (0-3/.%){0-2M/“/A-+)= 0.05 mm; ”‘/"" “Q : (o'l'af') (0'9‘ Mold/,4?) : 9-0? 1410/44 -'- Ha L: fix A'mifi'u/ Inca/4:19, 63411.4 : N4+ 0A; ’— H“ C4 f O-oémo/cr 0.06 rho/{5 masuwh, 0.0? Lao/(f r‘avf: 0 "0'0‘1‘ “(1&1 -—0.0U «(o/4r 0 ,eoul : 0-0 5 rue/4: 0-02 man; 0 4.014,; a-aymd‘, Ft’kd VD (V “'4. ’7 a ' 3 L"/' + O ' I £1.{' = 0 ' ‘I’ L-‘f ‘ (Au/0k!) Phat-1 mung/M'WJ; ./. Af 2 0M —— 0>°7r 1440/4: 0"] 2 ‘““‘_" : 0. a ’ 0 9‘ A? '5 M a 06 + r L— Ike/45 N“ 0“”‘T‘WM — 4- /$'M c; L+ _ CL '- ,___ 0'09 Mao/4.: ________~.. :_ o I 0.? A? O M Question #7 (16 pts) A student added 50 mL of a NaOH solution of unknown concentration to 100 mL of 0.400 M HCl. After that, the solution was treated with an excess of aqueous chromium (III) nitrate, resulting in the formation of 2.06 grams of Cr(OH)3. Determine the concentration of the original sodium hydroxide solution. on“ will 4‘ war :74 5.. 2 (4/471: (4) N60H+ #61 ’9 Nata-f 31° (fI'VJf) (4) 3N¢ay+ CrfNUJ)? "é Cr(0H)_-, +— BNAA/Oj. (Medal) fray lamina (4), run/4: 0H, r: rho/er {Ff = (ao/ ,L'k)(0-If rude/11+ If“): 0~0‘f tun/4: 0H— Fay rAa Jim ('0) ) / [41'] («(0/1) 1 (2.0g; an,be ‘ M; W“ /0? / "10“ €y(o”JJ 4 Na 0;, / (TAU mu {rm Cr+.?(0f()= 114-307): logj/mo/4) /oh’( 0 N¢ofi= 0’09 +o'd‘ S O./0 [kg/‘1 6 144414! 0-!0 nae/1.: Mao/r “(Lad/6“ 2 : M“ : a m Wham“ a_oro kf 2 a M Naoh’ (771;; if M 0/ V14. 4.0;?“ c( Amuuwfi lard/«4.1,- cz‘zvm 4, Querfin #77) Selected eguations and constants from Chapter 5: R = 0.082 lit atm K‘1 mole—1 : 8.314 1 I<-1 mole—1 PV = nRT P1V1/T1 = I’2Vz/T2 (KE)avg = (3/2)RT urms = «3121/ M) (effusion rate)1/ (effusion rate)2 = (4M2)/ (\IM1) [PobS + a(n/ V)2] x (V - nb) = nRT 1 2 H 11 111 IV V VI VII He 1.00797 1 4.00260 3 4 5 6 7 ‘ 3 9 10 Li Be B C N O F Ne 6941 ‘901213 1 10.311 12.0111 $110067 15.9994 139934 20179 11 , 12 13 14 15 16 17 P 13 Na Mg A1 Si P S Cl Ar 22.9397 24.305 26.9315 23.036 30.9737 1 32.064 35.453 39,943 1 19 20 21 22 23 24 25 26 27 23 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.0933 4003 449559 47.90 30.941 51996 54.9330 55.347 53.9332 . 53.69 63.546 1 65.377 69.72 4 72.59 74.9216 1 73.96 79.904 1 33.30 37 r 33 39 40 41 42 43 44 45 46 47 43 49 50 51 52 853 54 Rb Sr Y Zr Nb Mo Tc , Ru Rh Pd Ag Cd In Sn Sb Te I Xe 35.467 1 37.62 133.9059 91.22 92.9064 95.94 193.9062 _101.07 11021905 1064 .107.868 1 112.40 L114.32 _1 113.69 121.75 127.60 1 126.904 131.30 55 4 56 57 72 73 74 75 76 77 73 79 1 30 31 32 33 34 35 36 Cs Ba La Hf Ta W Re Os Ir Pt Au 1 Hg Tl Pb Bi 1 Po At Rn 132.905 137.34 4. 133.905 173.49 130.943 133.35 136.2 _190.2 192.2 “195.09 196.966 1 200.59 204.33 207.19 (203.930 L (209) (210 1 (222) 1 37 33 39 104 105 106 107 103 109 Fr Ra Ac (223) 226.025 227.027 7 53 59 1 60 61 62 63 1 64 1 65 F 66 67 63 69 70 71 Lanthanides 1 Ce Pr Nd Pm Sm Eu 1Gd Tb Dy Ho Er ‘Tm Yb Lu 1 1 140.12 140.907 144.24 I A 15035 151.96 157.25 158925 162.50 164.930 41 167.26 71 168.934 +173.04 174197 1 90 91 92 93 94 95 96 1 97 98 1 99 100 101 102 1 103 1 . - . I Achmdes 1 Th Pa U Np Pu Am Cm 1 Bk Cf Es Fm Md No 1 Lw 1 232.033 231.035 233.029 237.043 J (244) (243) _ (247) J (247) (251) (252) (257) (253) (259) . , ...
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This note was uploaded on 03/01/2008 for the course CHEM 105A taught by Professor Bau during the Fall '04 term at USC.

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Exam 2 Fall 2004 - ——————_—_——j...

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