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TheCityCollegeofNewYorkChemistry10301

FinalExamination,December16,2016Instructions:Donotcheatduringthisexamination.Youwillautomaticallyfailandmayfacefurtheraction.Pleasesitinalternatingseatsdirectlybehindthepersonintherowinfrontofyou.Writeclearly.Examswillnotbegradediftheworkoranswersarenotlegible.Questionsareonbothsidesofeachpieceofpaper.Youmaytearoffthelastsheet,whichcontainstheperiodictable,usefulequationsandconversionfactors.Donotwriteanyanswersorworkonthelastpage.Itwillnotbecountedduringgrading.Makesurethatallpagesareinyourpacket.Theremayhavebeenduplicationsoromissionsduringphotocopying.Useacalculator.Calculatorsoncellphonesarenotallowed.Pleasesilenceyourcellphone.Pleaseremoveearbuds,youmaynotlistentomusicoranythingelseduringtheexam.Anyuseofcellphonesisnotallowedduringtheexam.Youmaynotleavetheroomduringtheexam.Ifyoumustleavetogotothebathroom,youwillneedtobeaccompaniedbyaproctor.Forallproblems:Makesuretoprovideallanswerswiththecorrectnumberofsignificantfiguresandincludeunitsifappropriate.Youmustshowyourworktoreceivepartialorfullcredit.

FirstName:________________________LastName:___________________________CirclethenameofyourProfessor:Prof.BuProf.JansProf.LazaridisProf.SimmsProf.SteinbergSection:__________________________(ifyoudonotknow,pleaseleaveblank)LabTA:___________________________(ifyoudonotknow,pleaseleaveblank)RecitationLeader:_______________________________(ifyoudonotknow,pleaseleaveblank)Score:1._____/7 8.______/6 15._____/3 22._____/3

2._____/8 9.______/7 16._____/3

3._____/6 10._____/6 17._____/3

4._____/6 11._____/5 18._____/3

5._____/6 12._____/4 19._____/3

6._____/4 13._____/2 20._____/3

7._____/6 14._____/3 21._____/3

Total_____/100

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PartA:Problemsolvingquestions.Showyourwork(intermediateresults,equations,...)

1.Lacticacid,whichcontainsC,H,andO,haslongbeenthoughttoberesponsibleformusclesorenessfollowingstrenuousexercise.When5.000goflacticacidwassubjectedtocombustionanalysis,itproduced7.329gofCO2and3.000gofH2O.a.(5points)Whatistheempiricalformulaoflacticacid?b.(2points)Themolarmassoflacticacidis90.08g/mol.Whatisthemolecularformulaoflacticacid?

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2)(8points)Disulfidedichloride(S2Cl2)isusedinthevulcanizationofrubber,aprocessthatpreventstheslippageofrubbermoleculespastoneanotherwhenstretched.Itispreparedbyheatingsulfurinanatmosphereofchlorine:

S8(l)+4Cl2(g)!4S2Cl2(l)a)WhatisthetheoreticalyieldofS2Cl2when4.06gofS8isheatedwith6.24gofCl2?(Showyourwork)ThetheoreticalyieldofS2Cl2is:_____________b)Whichisthelimitingreactantwhen4.06gofS8isheatedwith6.24gofCl2?Thelimitingreactantis:___________c)IftheactualyieldofS2Cl2is6.55g,whatisthepercentageyield?Thepercentageyieldis:______________

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3)(6points)Theironcontentindrinkingwatercanbemeasuredbytitrationwithpotassiumpermanganate.Thereactionisrepresentedbytheequation:

5Fe2+(aq)+KMnO4(aq)+8H+(aq)!5Fe3+(aq)+Mn2+(aq)+4H2O(l)+K+(aq)

Determinetheconcentrationofironinasampleofwaterif25.0mLofthewaterrequires21.3mLof2.18x10–5MKMnO4toreachtheendpointofthetitration.

ConcentrationofFe2+(inM):_____________M4) (6 points)When coal is burned, the sulfur present in coal is converted to sulfur dioxide (SO2),which isresponsiblefortheacidrainphenomenon: S(s)+O2(g)!SO2(g)If3.15kgofSreactswithoxygen,calculatethevolumeofSO2gas(inL)formedat30.5˚Cand1.04atm.

VolumeSO2(inL):________________________

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5)(6points)Considerthefollowingcompleteoxidation-reductionreaction

Cl2(g)+2NaBr(s)!Br2(l)+2NaCl(s)a)Writethetwohalf-reactionsforthereactiongivenabove.b)Identifytheoxidizingandreducingagentinthisredoxreaction:

theoxidizingagentis:_____________

thereducingagentis:_____________

6)(4points)Balancethefollowingchemicalequations:

a)C5H12+O2!CO2+H2O

b) KOH+H3PO4!H2O+K3PO4

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7)A3.52-gsampleofammoniumnitrate(NH4NO3)isaddedto80.0mLofH2Oinaconstant-pressurecalorimeterofnegligibleheatcapacity.Thewaterisstirreduntilallammoniumnitratehasdissolved.Thetemperatureofthesolutiondropsfrom21.6to18.1˚C.

NH4NO3(s)+H2O(l)!NH4

+(aq)+NO3-(aq)∆Hsoln=?

Assumethatthespecificheatanddensityoftheresultingsolutionareequaltothoseofwater,4.18J/(g˚C)and1.00g/mL,respectivelyandassumethatnoheatislosttothecalorimeteritself,nortothesurroundings.a)(1points)Isthisprocessendothermicorexothermic(circlethecorrectanswer)?b)(5points)Calculatetheheatofsolution(∆Hsoln)ofNH4NO3expressedinkilojoulespermoleofNH4NO3?

Heatofsolution(∆Hsoln)=__________kJ/mol

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8)(6points)Calculatethedensityofhydrogenbromide(HBr)gasing/Lat0.961atmand46.0˚C?

DensityofHBr=___________g/L

9)a)(3points)DrawoneLewisstructure(includingallbondsandallnon-bondingelectronpairs/lonepairs)ofborontriiodide(BI3).Determinethenumberofvalenceelectronsinthemolecule.PredicttheidealbondanglesandmoleculargeometryaccordingtotheVSEPRmethodfortheboronatom.b)Totalvalenceelectrons(1point):____________c)MoleculargeometryaroundtheBatom(1point):______________d)IdealbondangleofI-B-I(1point):__________e)WhatisthehybridizationofboroninBI3?(1point)_____________

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10)(6points)Whatistheenergyandfrequencyofthephotontoraisetheelectroninahydrogenatomfromtheenergyleveln=2ton=4.

Energy:_________

Frequency:___________

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11)(5points)Fromthefollowingdata,

C(graphite,s)+O2(g)!CO2(g) ∆H˚rxn=-393.5kJ/molH2(g)+0.5O2(g)!H2O(l) ∆H˚rxn=-385.8kJ/mol2C2H6(g)+7O2(g)!4CO2(g)+6H2O(l) ∆H˚rxn=-3119.6kJ/molcalculatetheenthalpychangeforthereactionbelow:2C(graphite,s)+3H2(g)!C2H6(g)

∆H˚rxn=____________kJ/mol

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12)(4points)Acetylene(C2H2)hasatendencytolosetwoprotons(H+)andformthecarbideion(C22-),whichispresentinanumberofioniccompoundssuchasCaC2andMgC2

OnthesideyoualsohavetheorderingofthemolecularorbitalenergiesforC2

a) Fillinthevalenceelectronsofthecarbideionintothegivendiagraminordertocreatethemolecularorbitaldiagramforthecarbideioninitsgroundstate.b) Whatisthebondorderofthecarbideionbasedonyourdiagram?BondorderofC22-:______________c) Isthecarbideion(basedonyourdiagram)paramagneticordiamagneticThecarbideionis__________________

13)(2points)GivenbelowistheLewisstructureofICl4-

HowmanyelectrondomainsareonthecentralatomofICl4-:_______________

WhatisthemoleculargeometryofICl4-:_______________

I Cl

Cl

Cl

Cl

σ*2px

π*2py, π*2pz

π2py, π2pz

σ2px

σ*2s

σ2s

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PartB:Multiplechoicequestions.Selectandmarkthebestanswer.Thechoiceofmultipleanswerswillvoidtheanswersaltogether.

14.(3)Whatisthehybridizationofthesulfuratominthesulfateion,SO42-

A)sp B)sp2C)sp3D)sp3d E)sp3d215.(3)Thechemicalformulaforiron(III)oxideis

A)Fe3O2B)Ir3O3C)Fe3O3D)Fe2O3E)I3O316.(3)Inwhichofthefollowingcompoundsorionsistheoxidationnumber(inbrackets)fortheunderlinedelementincorrect?A)ClO4–/(+7)B)SO42–/(+6)C)CuO/(+2)D)NO2/(+3)E)NaOH/(+1)17.(3)Basedonthesolubilityrules,whichoneofthesecompoundsshouldbeinsolubleinwater? A)AgNO3B)NaOHC)NaClO3D)MgSO4E)BaSO4

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18.(3)Convert0.0031m3tocm3?

A)3.1cm3B)310cm3C)3100cm3D)31cm3E)3.1x106cm319.(3)Whichofthefollowingisacorrectsetofquantumnumbersforanelectronina4porbital? A) n=4,l=2,ml=+1 D) n=3,l=1,ml=0 B) n=4,l=1,ml=-1 E) n=4,l=3,ml=+2 C) n=3,l=2,ml=0

20.(3)Whatistheelectronconfigurationforsilicon? A) 1s22s22p63s13p3 D) 1s22s22p63p2 B) 1s22s22p63s23p1 E) 1s22s22p63s23p2 C) 1s22s22p63s421.(3)Whichoftheseatomshasthesmallestatomicradius? A)KB)SrC)BrD)CaE)I22.(3)Whichofthefollowingelementsisthemostelectronegative? A)SB)OC)FD)PE)N

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Possiblyhelpfulinformation(equations,constants,conversionfactors,etc.):

˚C=5/9(˚F–32)K=˚C+273.15cSH=q/[m(ΔT)]E=-RH(1/n2)whereRH=2.18x10-18J=13.6eVNA=6.0221x1023atoms/molc=2.9979x108m/sh=6.626x10-34Js=4.136x10-15eVsπ=3.141591amu=1.66x10-24g1in=2.54cm1m=1000mm=1x103mm1m=1x106µm1m=1x109nmR=0.082057Latm=8.3145Pam3=0.083145LbarmolKmolK molK

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