Exam 1 Fall 2004 - Chemistry 105a First letter of PLEASE...

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Unformatted text preview: Chemistry 105a First letter of PLEASE PRINT YOUR NAME IN BLOCK LETTERS last name Fall, 2004 Name: Exam #1 Sept 16, 2004 USC I.D.No: 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 Roints 1 13 l’ j 2 I 12 [ 3 14 + 4 4 I 12 mm (4/57? 5 10 a ._ kw 6 12 J 7 12 ‘1 1 |__ 8 15 _| L Total 100 I VIII 2 II III IV V VI VII He [4.00260 4 5 6 7 8 9 10 Be B C N O F Ne 6.941 9.01218 10.811 12.0111 14.0067 15.9994 18.9984 20.179 13 14 15 16 17 18 Al Si P S Cl Ar 26.9815 28.086 30.9737 32.064 35.453 39.948 21 22 23 23 29 30 31 32 I 33 34—79 35 36 1 SC Ti V Ni Cu Zn Ga Ge As Se Br Kr 44.9559 47.90 50.941 58.69 63.546 65.3” 69.72 72.59 749216 78.96 79.904 83.80 39 40 41 46 47 48 49 50 51 52 53 54 Y Zr Nb Pd Ag Cd In Sn Sb Te I Xe 88.9059 91.22 92.9064 106.4 107.868 112.40 114.82 118.69 121.75 127.60 126.904 131.30 57 72 73 78 79 80 81 82 83 84 85 TI, 86 La Hf Ta Pt Au Hg T1 Pb Bi Po At Rn 138,905 178.49 _‘ 180.948 195.09 196.966 200.59 204.3L 207.19 208.980 (209) (210 (222g 89 104 105 Ac 227.027 # 58 F 59 60 61 62 63 64 65 66 67 68 69 70 71 Lanthanides Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.12 140.907 144.24 150.35 151.96 157.25 158.925 162.50 164.930 167126 168934 173.04 174.97 90 91 92 93 [ 94 95 96 97 98 ‘ 99 100 101 102 103 Actinides Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw 232.038 Q1035 238.029 L237.041; (244) (243) (247) (247) (251) (252 IE2 (25% (259) I have observed all the rules of academic integrity While taking this exam signature Question #1 (13 pts) out the following operations and express the answers With the appropriate (a) Carry number of significant figures (4 pts) vauud off . m (1) 9.04 — 8.234 + 21.954 + 81.0 — 1.8765 [0L 9?”, { fan? I A'hl’L-Mrr rouud Off (11) 1.67495 x 2.998 + 2.54 /. 77677.._ m [1-76’ Aura” (b) (3 pts) The chromium atom, Cr (atomic mass 52) has: 2# protons, 26’ neutrons and 24‘ electrons. (c) (3 pts) The bromide ion, Br' (atomic mass 80) has: 35 protons, +5— neutrons and 36 electrons. (d) (3 pts) The platinum i911, Pt2+ (atomic mass 195) has: '7‘? protons, "7 neutrons and 75 electrons. _—-— mestion #2 (12 points) What are the formulas of: (a) (b) (C) (d) (e) (0 (Circle correct answers): lithium oxide (i) Li0 (V) Li03 x» m (vi) L1203 (iii) L102 (Vii) Li302 (iv) L130 (viii) none of the above magnesium nitrate (i) MgNOz (V) Mg2N02 (ii) MgN03 (Vi) Mg2N03 (iii) Mg(N02)2 (vii) Mg3N2 aluminum carbonate cobalt (III) sulfate: cadmium phosphate: ammonium nitride: ra- (Viii) none of the above (1) (ii) (iii) AlCO3 (Vi) Al4C3 AlCO4 (V ii) A13C03 COS (iv) C0803 (vii) C0804 C035 (v) C03803 (viii) €03,804 C083 (vi) Co(503)3 (ix) Co SO4)3 (x) none of the above CdP (iv) CdPO3 (vii) CdPO4 CdzP (v) Cds<POs>2 We“ CdP2 (Vi) Cd2(P03)3 (ix) Cd2(PO4)3 (x) none of the above NH4N (v) NH3N02 (viii) NH4N03 (NH3)3N (vi) NH4N02 (ix) NH4(N03)2 (x) none of the above Qgestion #3 (14 points) Balance the following equations. (a) Al4C3 + H20 —> CH4 + A120 3 (3pts) a 604' “+63 + HLO ——) 120”? 4- “2,03 at bat M463 4"};04 ?C,H‘f +(3fl4302 0 44 ./0k 0?) K + KN03 —> N2 + K20 (3ptS) Nb“: /¢+[:§l_k~o?-——z Uzi-K20 O 64: k + 1K~03 ——> N; + [2]ho [4 64-.- [ID I: + Jfin~03 ——> ’Vg'f’ 6/420 é--‘ Amway (C) C5H5N5 + 02 -—) C02 + H20 + N2 (4pt5) 6‘64 C;H;Ux 4 07, —’ la“: 4* HLO 4* “z ,. 5‘ H~b4£ 64,44er + ”z a 5 4°: fig‘uo‘” “2 - .6“ 5' N641- 4:”y’".r+ 02."a séozk’fulb *2“; '27 - 5’ 33w 0 54 afar/V, + 77-— 02,-—-> $402+2Hz°+ 2, 2. an] affix-‘11:. MM, ar4 ac +1.5/4 ‘ 22‘: {H o +$U *1,- i-LE W m {gjf M I! 47‘»- 1- AA (d) Ca3(PO4)2 + 5102 + C —) P4 + C0 + CaS103 (4ptS) p64: E643KP09)2 4- $702 f—C->P4+co+c.a$:03 4- C "" ’1, 4- 60+ /’6—{64I.‘03 do. 61; 2 Ca: (P09); 4— SIDL 5; 6:21 2 64, (P002, 4- @SI’OL + C ——-9 I, ,«v Co 4n 6 “£03 a 54 2 Ca? (ugh 4. gyroz + c -—+ p? ,Ego + 5 C‘s-:03 0’th {— éfioL-I—(IOIC—a ,0“ + 1040 +. 65490; c 6"" bf (hit/or) Question #4 (12 pts) (Please Show Work!) at 25° C is 775 miles per hour, how many (a) (6 pts) If the speed of sound through air seconds will it take sound to travel eleven kilometers? (Given. 1 mile = 1. 609 kilometers) [mil-é I hour éowia: 60446} [/1L~)<_.—_—-———)(__——————-—)<___——r~)(r————i" : 3/. 75' ,4.‘ mad; [6 4 14444 776’ rial/43’ India I hear //au ad off 32. Moth-{J _____._..———————— __________—.———- (b) (6 pts) A snowflake weighing twelve micrograms contains how many water molecules? (Given: one gram = 106 micrograms; Avogadro's number = 6.022 x 1023) t 7 mellwl<t #50 Arm fife—X ’W" ”W ”Kw/J / nae/4. HLo (/7. micyojyamy)(__________—————-“ lo ‘wzcvojrams’ n? art-1w; tho /7 -_: 4.01: x 1° 2 rauwl 'ff 4.0)(10 [yo/Acultr 0" 650 MM Question #5 (10 points): Bronze is an alloy (mixture) of copper and tin. If 2.58 grams of bronze is completely reacted with chlorine gas and the amount of tin (IV) chloride produced is 3.69 grams, what is the mass percent of tin in the original sample of bronze? [440101 ma}: of 9a,, 2 //y.7 +48%”): 260.57 /mo/¢ 9-7 04. M II Z/m/ 5 )__. {.657 q 51,, : (3-67; fuav)( 260.4'i/wo/4 £4615, AL? ”—12“ 11009: = (I-l7o W65! [7° ‘7 0631 w éyryjc 1‘— 2.1'fj Question #6 (12 pts) When 6 moles of C2H6 a of C2H6, 02, C02 and H20 are left at the re reacted (burned) With 14 moles of 02, how many moles end of the reaction? 7“» (.544 M flat 0; 24 I)“ 24.61.41.554, V’sd—fM will law—f aim 4‘ ”Ha/u 7 51H; rod...“ f ”.1... a; “a. aw. 12, [rho/.4; flfl‘o Ami “J Hum 0“.” A4 ”(V-£- 63.01 (Lfl— av“: é-#¢-l “1°(‘I 414104445 .‘ q moles of C2H6 = ’2 moles of 02 = 0 moles of C02 = 4? moles of H20 = / z {fill in the four blanks above) 6 l2- mestion #7 (1% pts) (please show work) An compound has a molar mass of 290.8 g/ mol and a general molecular formula of CxHyE, where E is an unknown element. If this compound contains 82.60% C and 5.20% H by mass, what is the molecular formula of this compound? What is the identity of the unknown element E? 'TEA /yloo/4. (290'Pj) 6f “wkumn gnu/“total Cxfilye’ 1414.3: 07 c = (a.d’2&o)(27°.g;): 2¢0_2/ C. ”$.15 4 H: (9~°5'20) (27D.fi) :‘ ’51]; j H 5°; max; .7 E :. 240'3—29'0-2-15'42. : 35.5; 4] 5 2904-2 ”0/44 a C '2. ( ): 20 ”Ali/m.“ /$'- /2 ”w“: ’7 '4 :' (flooJ’a/wo/a )= /5' [440/47 7 E: I (fin/w fWMq/A) Am“ m min mu «7 35-57 fué cone/nth v4- aA/u/u ..__~———-—- _____———- F:h¢ “fut/f Clef/,5“ Question #8 (15 pts) (please show work) (a) 1.911 grams of an unknown compound CxHyOZ, when burned in oxygen, produces 3746 grams of carbon dioxide and 0.987 grams of water. What is the empirical formula of this unknown substance? (12 pts) (3, H" 0 Kath) ; #912; c. .- 0.1/1; £130.77}; 0 __ #017— 0.111 0.77; ' rho/4; C" '_______..- rho/11H .‘ ——/“' Mao/(5' O /2~°/ I- On? ,5.” ': 0.09570 manic .' 0-/’9/2 Wfi/xffi/x 0.07843 rue/(4 O Divir‘duf 47 m {wm¢;/— «mu-‘64,: (o_o¢f(?)/ W4 7J3 4.0J’J'IO o-Ito/ o OYf‘3 C: H10 : -————”' .‘ M) .' {R— 0.01.41? ( 0J4“? o. “(in {.75 ,- 2.25 x / Maw. «'4 /’34; " 2’5? 'I I 51> W4 fluffy/«‘4 fwwafcx to C7 Hg0¢ (b) If the molar mass of the compound is 314.3 g/ mole, What is the molecular formula? (3 ptS) SMffrir—d mar! : 7é)+ 4004' 4(0) = 7 (11.0!)4— 51/4705) 4’ 4 (ll) 2 U7. 2 j/mou 5:9 fl-c Wanda/a.— fWI/Mk{£. L; cl? ”/3” of Extra Question for 2005 review @estion #6 (16 points): Zintl phases are stoichiometric alloys made up of an alkali metal and a group IV metal. For example, rubidium and germanium form a Zintl phase (Rb5Ge9) when heated together acording to the equation: 5Rb + 9Ge -> Rb5Ge9 (a) Which is the limiting reagent when 258.0 grams of rubidium and 369.0 grams of germanium are combined in this way? (please show work!) (8 pts) 47uMMu'y: “’47; 7 Jain.)- fvra‘hw. #94, an; "wc .' 0‘ 044 . ”M " (211°; 45% ’"‘ ’ 4W "“’ "‘*")(__L~_’°’° 9 We!) ; 412.3, a in; 46 5' mm '95 / mm m, a, / o/ 4 / JIM—I Info. 7- £5 (2:4; G-c)(--—-—"" m 4 e)( W .1 ¢¢)(___L___ r (47:) (lo. $7 36,“; 72 (i 6‘: 7 mm..- (c / Mal; £6,647 4" If I'm-‘5'“? K4424“! Out/Lo cl '# L / nah.“ ——-'-—""“ 2"? AI; ( M)< 0 503 mol ( f ) if 4')- ,46 )5: I. [e / nun/4 (e . (3;; fi)( )(L) = 0.4éJ’ wok j ‘72 J; {c 7/, “oak ‘wq/I‘r ”bu-W6” . .'. 6‘ ‘3' “wilful y‘az‘w. (b) How many grams of the excess reagent are left over at the end of the experiment? (8 pm) Man ,7 ,4; “.4 .7, : (357; (e)( lm‘l“[< ______)(_—___ frag/4:49) (.00, J’ #J 72 4/ (e 7 mm re) (/ ml. 41, ', IQ‘ pf}, ova :- 2r5’,a —2l,p,.‘f : /5'KZ k6 lsz thy ...
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