exam_1_spring_2006

exam_1_spring_2006 - Chem 105a Exam 1 Last First Initial...

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Unformatted text preview: Chem 105a Exam 1 Last First Initial Tuesday, February 7, 2006 Last 4 digits Student ID # _ Professor Stephens Lab TA's Name Lab Day & time: Major Questions Points Score Grader 1 5 2 6 3 6 4 8 5 12 6 9 7 12 8 12 9 6 11? 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 on12 pages. Please count them before you begin. Exam 1 1. (5 pts.) What are the names of the following elements: a) Fe from 2. (6 pts.) What are the formulae of the following compounds: a) methane our b) ammonium nitrate NW+N°3 c) lithium carbonate Liza): d) methanol at} o H (CW—Q ) e) nitrous oxide N10 f) barium chromate @Q Crgx‘. 3. (6 pts.) A sample of cobalt metal contains 5.00 x 1020 atoms. Avogadro's Number is 6.022 x 1023. a) Calculate the number of moles of cobalt. wa<Q= 23 (a.sz vs N chm: -—-— 13 MM -= \ OJ'UMF- (3.022 3(\Q 2Q 2 6.6%: *\Q . g~®*\0 Q OAVV‘AJ = W ,2? C: «37.2 3* \Q ~13 = Q.830 x\Q WQ‘QJ b) Calculate the number of grams of cobalt. ‘ N‘Hg Cm stbvb 55293 3 -3 ' Q.830*\Q MM WW -3 ’- 7K\Q 7‘ —-3 : 43,9\ mo 8. 4. (8 pts.) Carvone is an organic compound occurring naturally in caraway seeds and in Spearmint. Its formula is C10H14O. a) Calculate the molar mass of Carvone. “MAW, N0,” = (Q x 01km. C + \W 7g chumss H b) Calculate the mass percentage of the elements C, H and O in Carvone. \ MM C‘§H‘$Q hoax/em, l>’0.23 0w( (Wham? lZQJ j C. \W.\ 5 H O (b M’LN ’- \u‘nA nae? = \ = ‘10-! ><\ oar-9% 7s C “’3 “3"” my; Q ——————————- 5. (12 pts.) The stimulant caffeine contains 49.48% C, 5.15% H, 28.87% N and 16.49% 0 by mass. Its molar mass is 194.2. Determine the molecular formula of caffeine. (2.o\ 5hf3 H : \MdLno H = bo\\ 1'00)? (6 2 .Q 14.01 ‘b‘fci '3 O “0.4% “Jung 3 in; No Mdlcr W — <4v<lZQ\)4—()x\®8) *Qmwm) +wag) - 97.\ = 194.2. 6. (9 pts.) Balance the following reactions: a) NH3(g) + 02(g) —> NO(g) + H20(g) (The first step in the commercial production of nitric acid) 40mg 4» {Oz ———7 (N0 + Largo b) PbS(s) + 02(g) -> PbO(s) + SOz(g) (The first step in converting the mineral galena (PbS) into elemental lead) 2mg +302 ~> 2&0 +250; C) (3814180) + 02(8) —’ C02(8) + H20(g) (Combustion of octane (gasoline)) 2939“ +— 25‘ oz ——7 \(o CQZ 1» \8 H10 7. (12 pts.) Hydrogen cyanide, HCN, is produced industrially by the reaction: NH3 + 02 + CH4 —> HCN + H20 a) Write a balanced equation for this reaction: 2W3+702 *ZU’w "'7 ZWW+(°‘*aQ b) If 500 kg of each reactant (NH3, 02, CH4) is mixed together, which is the limiting reactant? Wuhan-Mn : W3 l‘T-QZS Oz 32.QK3 CW“. \Bnuq. W; = 2.9W‘AKQ‘” “AQUA “Ah gdbkb 02 3 V591“ \Q‘ kay: 0; 5mm 0+4 = 3n vv N‘ may, cuM ‘5; (W3 (:3 RWWVv‘.‘ ) 2.9“ XN‘ “Mme L310 flows 3. HQN OZ 3 J 3.\‘2,1~ NW Noah- 8 (12 pts.) Nitrogen gas can be prepared by passing gaseous ammonia over solid Cu(II) oxide at high temperatures. The other products of the reaction are solid copper and water vapor. A sample of 18.1 g ammonia gas is reacted with 90.4 g CuO. a) Which is the limiting reactant? \8.l3 W3 "’ ‘8" wtdxsm = LOG ‘W.O\ + 31~L009 9mm?) 0&0 "- MM 2 .|\+ (oz. 5’! +\\..o mo, W\\"e~ 3/Z$\.QG «who 0A0 b) How many grams of nitrogen gas will be formed? 3mm» (Mo —-> ‘W‘NNl LN 3 (3ng MMS N2 ‘-\\l. MJLI/a CNU _) '- ~— = o.3§+(z$\\ttm) 3‘ 5 N7_ W 9. (6 pts.) The ocean contains salt: NaCl. The molarity is approximately 5 M. Assuming the concentration is 4.8 M, calculate the volume of sea water which contains 7.5 kg NaCl. ; 5 2 Q9r 4:1: % "23 $ (3 3’ 1‘5; Ndho sch/Va = 7{x\0 {8&4 = [.23 x‘QL MdUo _______________________.___— 10 10. (5 pts.) Are the following compounds soluble or insoluble in water? In each case circle the correct answer. a) AgCl Soluble Insoluble b) Ca(NO3)2 Soluble Insoluble c) K3PO4 Soluble Insoluble d) CaSO4 Soluble Insoluble e) Cu(OH)2 Soluble Insoluble ll. (9 pts.) Write complete ionic equations and net ionic equations for the following reactions (all compounds are in aqueous solution): a) Cuso4 + NaZS —> OMS 1, +- NQ250+ 2—- CMZ” 4. 50+ s- ZNoJ’ + S ——> (Ask l— zwefi + 8m?- QA2++SZ‘ "9 12 12. (10 pts.) What mass of barium sulfate precipitate is produced when 100 mL of a 0.13 M solution of barium chloride is mixed with 250 mL of a 0.025 M solution of iron (III) sulfate? 300%; +- RZGSW)? s3 9050+ ll +ZRQZ (GDML sz Gauz CM?»va m) venue = om? mm GaKLL \Suo bro Mk 0.02? m $190+): W Eli—o— * Q.Qz3’ — 6.00523- WM \QQO QzQCN—Dg DISOQ'LX’ M6114 (£20509): meg} bail-fl Q.Q0Q23’X3 : 04373, MJLV: Raul Qakstz {3 \xwwtke MW 0.0K? wxdb.» {lan ~> 0.0l3wdb” [33.30%]~ = 6.0"; x 223.3% _-. 3&3 j (3:309, «tum—er me‘ 58V Ammmv Amway Arms Amway Sway ASN.9 €va Amway can ofimm @me 04mm oamn 5 c2 22 Eu 3. .6 vi :6 :2 E A5 2 E .F 825.2 mod N2 :: 09 mm. mm no on mo 3 mm mm 3 cm owt 04m: Qwo— mfio. 3‘2 mdo— $me 2.9 cogmfi #09 33v NS: 0.03 <03 .5 A; Ea km a: E A; 5 am am :5 oz 5 8 82:22.5 K or me we no we mo vw m0 me E on mm wm $09 Amway ficmv “$8 $00 20S o‘bmm 0.0mm Ammmv :2 m: E mm 3 E 9< «m a [4 09 $2 8. mx: rmofi I4 «9 aw fil mm hm Amway 8—9 309 Odom MEN #3..” odow. 062 memo— mdg Noo— m‘ewfi $.me mom: WwC me— 05.2 mam— ; 2 a E i P w: =< E : we a: 3 «a E S «a 8 0w mw .I § I. mm r Nw 3w ow on wb F on mu 5 m» E m om 4| mmlL 22 J 0.8.; 05: mgfl Em: WV: «H: 062 «,8. Que :2 8% 3.3 590 man—o E‘ww NOE Dmmw ox _ as am 5 E no 3 E .E 3— : o: .2 “a w 6 £— vm mm .._I am E om av wv Bu 3 mv vv 9 me. 3 3 mm mm r hm owmw omdh 033 ‘83. “can mhmc ammo 03.8 mo‘wm 3.wm bvwwm vain @ma._m 3.0m wwfiv 8.3 8.0V ofimm E 5 am 2 5 5 as .6 _z co «m =2 6 > F em .6 M 0m mm vm mm mm Fl. gm em on ma hm on mm «m mm mm :1. cm a QOm 91mm Sam 8.0m oowm wmdn 4| Rem moan 2 6 m a a 2 w: «z E C E D E Q .2 I x. cm 0.0— odfi 5.3 5,2 5,9 Sod $0.0 oz m o z o m an E 9 al w b o m w m 83» woo,— 9: :> 5 > E E E m N M E> H mrerEmEm NEH m0 MAM—<9 UHQOEmE ...
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exam_1_spring_2006 - Chem 105a Exam 1 Last First Initial...

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