NYC AP CHEM Formative Assessment 2 STUDENT FINAL · (B) The slope T is steeper than R because the specific heat of ethanol liquid is less than the specific heat of ethanol in the

Copyright © 2017 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org 1

L, mL = liter(s), milliliter(s) mm Hg = millimeters of mercury g = gram(s)

E = hQ c = OQ

Q = frequency

Planck’s constant, h = 6.626 u 10�34 J s Speed of light, c = 2.998 u 108 m s�1

Avogadro’s number = 6.022 u 1023 mol�1

Electron charge, e = �1.602 × 10�19 coulomb

Kc = [C] [D]

[A] [B]

c d

a b, where a A + b B R c C + d D

Kp = C D

A B

( ) ( )

( ) ( )

c d

a b

P P

P P

Ka = [H ][A ][HA]

� �

Kb = [OH ][HB ][B]

� �

Kw = [H+][OH�] = 1.0 u 10�14 at 25qC = Ka u Kb

pH = pKa + log [A ][HA]

�

Kc (molar concentrations)

Kw (water)

ln[A] t � ln[A]0 = � kt

> @ > @0A A

1 1

t � = kt

t½ = 0.693k

t½ = half-life

AP CHEMISTRY ASSESSMENT 2

AP® CHEMISTRY EQUATIONS AND CONSTANTS

Throughout the exam the following symbols have the definitions specified unless otherwise noted.

J, kJ = joule(s), kilojoule(s) nm = nanometer(s) V = volt(s) atm = atmosphere(s) mol = mole(s)

ATOMIC STRUCTURE E = energy

O = wavelength

EQUILIBRIUM

pH = � log[H+] , pOH = � log[OH�]

14 = pH + pOH

pKa = � logKa , pKb = � logKb

Equilibrium Constants

Kp (gas pressures) Ka (weak acid) Kb (weak base)

KINETICS

k = rate constant t = time

Copyright © 2017 National Math + Science Initiative, Dallas, Texas. All rights reserved. Visit us online at www.nms.org

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1 atm = 760 mm Hg = 760 torr

PV = nRT

moles A PA = Ptotal u XA, where XA = total moles

= PA + PB + PC + . . .Ptotal

mn = M

K = qC + 273

D = mV

1 2KE per molecule = mv2

A = abc

M = molar mass

KE = kinetic energy

A = absorbance

R = 8.314 J mol�1K�1

= 62.36 L torr mol�1 K�1

D D'Sq = ÇS products � ÇS reactants

D D'Hq = ÇDHf products � ÇDHf reactants

D D'Gq = ÇDGf products � ÇDG reactantsf

'Gq = 'Hq � T'Sq

= �RT ln K

= � n�Eq

qI =

t

Sq = standard entropy Hq = standard enthalpy Gq = standard Gibbs free energy

Eq = standard reduction potential

�� = 96,485 coulombs per mole of electrons

Faraday’s constant,

1 joule

1 volt =1 coulomb

GASES, LIQUIDS, AND SOLUTIONS

Molarity, M = moles of solute per liter of solution

THERMODYNAMICS / ELECTROCHEMISTRY

q = mc'T

P = pressure V = volume

T = temperature n = number of moles m = mass

D = density

v = velocity

a = molar absorptivity b = path length c = concentration

Gas constant,

= 0.08206 L atm mol�1 K�1

STP = 273.15 K and 1.0 atm

Ideal gas at STP = 22.4 L molí1

q = heat m = mass c = specific heat capacity T = temperature

n = number of moles

I = current (amperes) q = charge (coulombs) t = time (seconds)


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MULTIPLE CHOICE

Directions:Eachofthequestionsorincompletestatementsbelowisfollowedbyfoursuggestedanswersorcompletions.Selecttheonethatisbestineachcaseandentertheappropriateletterinthecorrespondingspaceontheanswersheet.

1. Asampleofawhite,crystallinesolidcompoundatroomtemperaturedidnotconductelectricityasapuresolid.Thesolideasilydissolvedinwaterbutstilldidnotconductandelectriccurrent.Whichofthefollowingtypesofinteractionsismostlikelyfoundbetweentheparticlesinthesubstance?(A)Ionicbonds(B)Metallicbonds(C)Covalentbonds(D)Hydrogenbonds

Element Formulas F F2

Cl Cl2, ClF, ClF3

Br Br2, BrF, BrF3, BrF5 I

2. Basedontheinformationaboveandperiodictrends,whichofthefollowingisthe

besthypothesisregardingtheformulasformedbyI?(A)IwillformonlyI2solid.(B)IwillformonlyI2andIF.(C)IwillformonlyI2,IF,IF3,andIF5.(D)IwillformI2,IF,IF3,IF5andIF7.


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3. BasedontheionizationenergiesofanunknownelementXgiveninthetableabove,whichofthefollowingismostlikelytheempiricalformulaofanoxideofelementX?

(A)XO2(B)XO4(C)X2O(D)X2O4

Ionization Energy (kJ/mol)

First 780 Second 1575 Third 3220 Fourth 4350 Fifth 16,100


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4. Lookingatthespectraforsodiumandpotassiumabove,whichofthefollowingwouldbestexplainthedifferenceinbindingenergyforthe3selectrons?(A)Potassiumhasagreaternuclearchargethansodium(B)Potassiumhasmoreelectron-electronrepulsionsthansodium(C)Sodiumhasonevalenceelectron(D)Sodiumhaslesselectronshieldingthanpotassium


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5. Whichofthefollowingparticulatediagramsbestshowstheformationofwatervaporfromhydrogengasandoxygengasinarigidcontainerat125˚C?

(A)

(B)

(C)

(D)


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6. Anexperimentdeterminedthatacompoundcontainingsodium,carbonandoxygen

iscomposedof43.4%byweightsodium,11.3%byweightcarbonandtherestoxygen.Themostlikelyempiricalformulaforthecompoundis

(A) Na2CO (B) Na2C2O2 (C) Na2C2O4 (D) Na2CO3

7. Tochooseawavelengthforanalysisofdyeinafoodsample,astudentrecordstheabsorbancespectraofthefooddyesolutionsfoundinthegraphabove.Whichwavelength(s)shouldthestudentsetthespectrophotometerinordertoanalyzeafoodproductforyellowdye?(A)320nm(B)420nm(C)520nm(D)620nm

320

360

400

440

480

520

560

600

640

680

Wavelength (nm)

Abso

rban

ce

0

0.2

0.4

0.6

0.8

1.4

1.8

1.2

1.0

Absorbance vs. Wavelength for Three SolutionsRed Soln Yellow Soln Green Soln


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8. Themassspectrumofanelementispresentedinthediagramabove.Basedonthespectrum,whichofthefollowingcanbeconcludedaboutthiselement?(A)Theelementisamemberoftheboronfamilywhereeachpeakrepresentsthe

lossofeachelectron.(B)Theelementamemberofthealkaline-earthmetalswithanatomicnumberclose

to20.(C)Theatomicmassoftheelementis21.(D)Theatomicmassoftheelementisbetween20and 21.

9. A70.0gsampleofmetalat80.0˚Cisplacedinto100.0gofwaterat22.0˚Ccontainedinacoffee-cupcalorimeter.Themetalandwatercometothesametemperatureat30.0˚C.Assumenoheatisabsorbedbythecalorimeter.Thespecificheatofwateris4.2J/g˚C.Theapproximatespecificheatofthemetalisclosestto

(A) 0.388Jg-1˚C-1

(B) 0.490Jg-1˚C-1

(C) 0.960Jg-1˚C-1

(D) 1.97Jg-1˚C-1


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10. A10.0mLsampleof0.100MK3PO4isaddedto20.0mLof0.300MAgNO3.Silverphosphateprecipitates.TheconcentrationofAg+ionsinsolutionAFTERreactionis,

(A)0.030M(B)0.100M(C)0.200M(D)0.300M

11. Thelatticeenergyofasaltisrelatedtotheenergyrequiredtoseparatetheions.Whichrepresentsthecorrectorderoftherelativelatticeenergiesfortheionicsolidsbelow?

NaCl,CaO,KI,MgO

(A) KI<MgO<NaCl<CaO(B) KI<NaCl<CaO<MgO (C) NaCl<KI<CaO<MgO(D) NaCl<CaO<MgO<KI


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12. Theheatingcurveforasampleofpureethanolisprovidedabove.Thetemperaturewasrecordedasa100.0gsampleofsolidethanolwasheatedataconstantrate.Whichofthefollowingstatementscanbesupportedusingtheheatingcurveforethanol?(A)EnergymustbereleasedasethanolmovesfromregionPtoregionT.(B)TheslopeTissteeperthanRbecausethespecificheatofethanolliquidisless

thanthespecificheatofethanolinthegaseousphase.(C)Theheatofvaporizationisgreaterthantheheatoffusionforethanol.(D)Solidethanolisthemoststableformforethanol.

Questions13and14refertothefollowingreaction: CaCO3(s)+2HCl(aq)→CaCl2(aq)+CO2(g)+H2O(l)Thereactionbetween0.500molesofCaCO3(s)and0.500molesofHCl(aq)isrepresentedbytheequationabove.Astudentmonitoredthereactionandcollectedthegasinapreviouslyevacuated1.0Lcontainerat300K.

13. WhatistheapproximatepressureoftheCO2(g)inthecontainerattheendofthereaction?

(A)6.15atm(B)12.3atm(C)24.6atm(D)49.3atm


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14. Identifythecorrectnetionicequationforthereactionrepresentedabove.

(A)CaCO3(s)+2HCl(aq)→CaCl2(aq)+CO2(g)+H2O(l)

(B)CO32-(s)+2H+(aq)→2Cl1-(aq)+CO2(g)+H2O(l)

(C)CaCO3(s)+2H+(aq)→Ca2+(aq)+CO2(g)+H2O(l)

(D)CO32-(s)+2H+(aq)→CO2(g)+H2O(l)Questions15–17refertothefollowingreaction:

3Cu(s)+8HNO3(aq)→3Cu(NO3)2(aq)+2NO(g)+4H2O(l)Inanexperimenttodeterminethepercentcopperinabrasssample,thereactionshownaboveisperformedinafumehood.Observationsincludebubbles,temperatureincreasingandcolorchangesinthesolutionfromcolorlesstogreentoblueandfinallyabrowngasisobserved.

15. Whichformula/namecombinationisincorrect?(A)HNO3/nitricacid(B)NO/nitricoxide(C)NO2/nitrogendioxide(D)Cu(NO3)2/copper(II)nitrate

16. Ifthebrasssampleweighed0.636gramscalculatetheapproximatevolumeof

16.0MHNO3(aq)neededtofullyreactthesample.Assumethatthebrasssampleispurecopperforcalculationpurposes.

(A)0.0016mL(B)0.16mL(C)1.6mL(D)16.7mL


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17. NO(g)isacolorlessgas,however,thestudentobservedabrowngasasthereaction

progressed.Thefollowingreactionsarethoughttooccur: 2NO(g)+O2(g)→2NO2(g) 2NO2(g)DN2O4(g)

Whichofthefollowingbestrepresentsthestructureofthedinitrogentetraoxidegasproducedinthesecondreaction?

(A)

(B)

(C)

(D)

NNO

O

O

O

NNOO O

O

NNOO O

O

NN OOO O


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Questions18–20refertothefollowingdata:Thetablebelowcontainsinformationaboutsamplesoffourdifferentgasesat0°C.Thegassamplesineachcontainerareheldataconstantvolumeof44.8L.

Container Gas Pressure(atm)

MassofSample(g)

1 H2 1.00 ?

2 NH3 1.00 ?

3 ? 1.00 56.0

4 SO3 1.00 160.

18. Onthebasisofthedataprovidedabove,thegasincontainer3couldbe(A)CO(B)C4H10(C)Cl2(D)N2O

19. Undertheconditionsgiven,considercontainers1,2,and4only.Whichstatementistrueregardingthesethreegases?(A)Container4willhavegreaterpressurethancontainers1and2.(B)Container4containsafewernumberofmoleculesthancontainers1and2.(C)Themoleculesincontainer1willmoveatafasterspeedthancontainers

2and4.(D)Themoleculesinallcontainerswillmoveatthesamespeed.

20. Whichstatementistrueregardingthegasesincontainers2and4?(A)NH3andSO3bothhavetrigonalplanarmoleculargeometries.(B)NH3isapolarmoleculewhileSO3isanonpolarmolecule.(C)ThebondanglesinNH3aregreaterthanthebondanglesinSO3.(D)NH3andSO3havebothsigmaandpibonding.


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21. WhichoftheimagesbelowbestrepresentsanioniccompoundlikeNaCldissolvedin

water?

A. B.

C. D.

22. Whichofthefollowingisthereasonthationizationenergygenerallyincreasesfromlefttorightacrossthesecondperiodoftheperiodictable?(A)Astheatomicnumberincreases,theelectronsarehardertoremove.(B)Shieldingincreaseswithanincreaseinnumberofelectrons.(C)Astheatomicnumberincreases,moreelectronsareaddedtotheatoms,thus

increasingtheelectron-electronrepulsions.(D)Astheatomicnumberincreases,moreprotonsinthenucleuscauseanincrease

intheeffectivenuclearcharge,makingithardertoremovetheelectrons.

23. Oxidationofthecyanideionproducesthestablecyanateion,OCN–1.Thefulminateion,CNO–1,ontheotherhandisveryunstable.Fulminatesaltsexplodewhenstruck;Hg(CNO)2isusedinblastingcaps.Whichexplanationbestexplainswhythefulminateionissounstablecomparedtocyanate?

(A)Nitrogenatomistooelectronegativetobeacentralatomintheion;carbonisa

muchbettercentralatom(B)Eachatominfulminatepossessesaformalchargewhileincyanateonlyoxygen

hasaformalchargeof–1(C)Thenegativechargeonfulminatecausesittoreactviolently(D)Nitrogenisunabletoexpanditsoctet


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24. Whichofthefollowingbestdescribesthepreparationof100.0mLof0.250MNaOH

solution?

(A)Measure0.25molesofNaOHpelletsonabalance,placeina100mLbeaker;measure100.0mLofdistilledwaterinagraduatedcylinderandmixcompletely.

(B)Useavolumetricpipettomeasure0.25mLofNaOHandplaceina100.0mLvolumetricflask;filltothelinewithdistilledwaterandmix.

(C)Useabalancetomeasureout1.00gramsofNaOH;addthesolidtoa100.0mLvolumetricflask,filltothelinewithwaterandmix.

(D)Measure4.17mLof6.0MNaOHina100mLgraduatedcylinderandadd95.83mLofdistilledwaterandmixthoroughly.

25. Brass,asubstitutionalalloy,isasolutioncomposedmainlyofcopperandzincatoms.Whichofthefollowingdiagramsbestrepresentsanalloyofbrass? (A)

(B)

(C)

(D)


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FREE RESPONSE

CH4(g)+2Cl2(g)→CH2Cl2(g)+2HCl(g)

26. Methanegasreactswithchlorinegastoformdichloromethaneandhydrogenchloride,asrepresentedbytheequationabove.(a) A25.0gsampleofmethaneisplacedinareactionvesselcontaining2.58molof

Cl2(g).(i)Identifythelimitingreactantwhenthemethaneandchlorinegasesare

combined.Justifyyouranswerwithacalculation.(ii)CalculatethetotalnumberofmolesofCH2Cl2(g)inthecontainerafterthe

limitingreactanthasbeentotallyconsumed.

InitiatingmostreactionsinvolvingchlorinegasinvolvesbreakingtheCl–Clbond,whichhasabondenergyof242kJmol–1.(b) Calculatetheamountofenergy,injoules,neededtobreakasingleCl–Clbond.(c) Wouldaredlaser,wavelengthof656nanometers,supplythenneededenergyto

breaktheCl–Clbond?Justifyyouranswer.(d)(i)DrawtheLewisstructurefordichloromethane,CH2Cl2(g),intheboxprovided. (ii)Identifythemolecularstructureforthismolecule.


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(e)ConsiderthefollowingBoltzmanndistributioncurverepresentingtheproductsofthisreaction.IdentifythepeakthatrepresentsHCl.Explainyourreasoning.

0 2200 4000 6000 8000 10000 12000 14000

Speed (m/s)

Num

ber o

f Mol

ecul

es


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27.Propane,C3H8,isahydrocarbonthatiscommonlyusedasfuelforcooking.

(a) Writeabalancedequationforthecompletecombustionofpropanegas,whichyieldsCO2(g)andH2O(l).

(b) (i)Calculatethevolumeofairat30°Cand1.00atmospherethatisneededtoburncompletely10.0gramsofpropane.Assumethatairis21.0percentO2byvolume.

(ii)Ifthereactionwereperformedatahigheraltitude,wouldthevolumeofairneededtocompletelyreactthepropanebegreaterthan,lessthanorequaltothecalculatedvolumeatsealevel?Explain.

(c) Theheatofcombustionofpropaneis–2,220.1kJ/mol.Calculatetheheatofformation,ΔH°f,ofpropanegiventhatΔH°fofH2O(l)=–285.3kJ/molandΔH°fofCO2(g)=–393.5kJ/mol.

(d) Assumingthatalloftheheatevolvedinburning30.0gramsofpropaneistransferredto8.00kilogramsofwater(specificheat=4.18J/g°C),calculatetheincreaseintemperatureofwater.


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28.AstudentisassignedthetaskofdeterminingthenumberofmolesofwaterinonemoleofMgCl2•nH2O.Thestudentcollectsthedatashowninthefollowingtable.

Massofemptycontainer 22.347g

Initialmassofsampleandcontainer 25.825g

Massofsampleandcontainerafterfirstheating 23.982g

Massofsampleandcontaineraftersecondheating 23.976g

Massofsampleandcontainerafterthirdheating 23.977g(a) Explainwhythestudentcancorrectlyconcludethatthehydratewasheateda

sufficientnumberoftimesintheexperiment.

(b) Usethedataaboveto(i) calculatethetotalnumberofmolesofwaterlostwhenthesamplewas

heated(ii) determinetheformulaofthehydratedcompound

(c) Adifferentstudentheatsthehydrateinanuncoveredcrucible,andsomeofthesolidspattersoutofthecrucible.Whateffectwillthespatteringhaveonthecalculatedmassofthewaterlostbythehydrate?Justifyyouranswer.


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Documents

NYC AP CHEM Formative Assessment 2 STUDENT FINAL · (B) The slope T is steeper than R because the specific heat of ethanol liquid is less than the specific heat of ethanol in the