2017 chemistry-nht written examination 2€¦ · d. 3-chloropentane. section a – multiple-choice...

CHEMISTRYWritten examination

Wednesday 7 June 2017 Reading time: 10.00 am to 10.15 am (15 minutes) Writing time: 10.15 am to 12.45 pm (2 hours 30 minutes)

QUESTION AND ANSWER BOOK

Structure of bookSection Number of

questionsNumber of questions

to be answeredNumber of

marksA 30 30 30B 11 11 90

Total 120

• Studentsarepermittedtobringintotheexaminationroom:pens,pencils,highlighters,erasers, sharpeners,rulersandonescientificcalculator.

• StudentsareNOTpermittedtobringintotheexaminationroom:blanksheetsofpaperand/orcorrectionfluid/tape.

Materials supplied• Questionandanswerbookof37pages.• Databook.• Answersheetformultiple-choicequestions.

Instructions• Writeyourstudent numberinthespaceprovidedaboveonthispage.• Checkthatyourname andstudent numberasprintedonyouranswersheetformultiple-choice

questionsarecorrect,andsignyournameinthespaceprovidedtoverifythis.• Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.• AllwrittenresponsesmustbeinEnglish.

At the end of the examination• Placetheanswersheetformultiple-choicequestionsinsidethefrontcoverofthisbook.• Youmaykeepthedatabook.

Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room.

©VICTORIANCURRICULUMANDASSESSMENTAUTHORITY2017

SUPERVISOR TO ATTACH PROCESSING LABEL HEREVictorian Certificate of Education 2017

STUDENT NUMBER

Letter

2017CHEMISTRYEXAM(NHT) 2

SECTION A – continued

Question 1Thediagrambelowrepresentsaparticularacid-basetitration.

14

7pH

025

volume of titrant added (mL)

Whichoneofthefollowingstatementsaboutthistitrationiscorrect?A. Attheequivalencepoint,thepHofthesolutioniscloseto4.5B. AsolutionofastrongbasehasbeendeliveredbytheburetteC. PhenolphthaleinisasuitableindicatorforthisreactionD. Thetitrantisasolutionofaweakacid

Question 2Manganesecanexistinseveraloxidationstates.Inwhichcompoundismanganeseinitshighestoxidationstate?A. Mn2O3B. KMnO4C. MnCO3D. MnO(OH)

Question 3ThesystematicnameofCH3C(CH3)ClCH2CH3isA. 1-chloro-1,1-dimethylpropane.B. 3-chloro-3-methylbutane.C. 2-chloro-2-methylbutane.D. 3-chloropentane.

SECTION A – Multiple-choice questions

Instructions for Section AAnswerall questionsinpencilontheanswersheetprovidedformultiple-choicequestions.Choosetheresponsethatiscorrect orthatbest answers thequestion.Acorrectanswerscores1;anincorrectanswerscores0.Markswillnotbedeductedforincorrectanswers.Nomarkswillbegivenifmorethanoneansweriscompletedforanyquestion.Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.

3 2017CHEMISTRYEXAM(NHT)

SECTION A – continuedTURN OVER

Question 4Sodiumhydroxide,NaOH,solutionscarefullypreparedfromanalytical-gradeNaOHpelletscannotbeusedasprimarystandardsinacid-basetitrations.ThisisbecauseA. theNaOHsolutionspreparedarecolourless.B. strongbasesarecausticandcancausechemicalburns.C. theNaOHpelletsaretoodifficulttoputintovolumetricflasks.D. theexactconcentrationoftheNaOHsolutionsmadefromthepelletsisunknown.

Question 5Apureproteinsampleismixedwithdiluteacidat25°C.Whichstructure(s)oftheproteinislikelytobedisrupted?A. primaryandsecondaryB. secondaryandtertiaryC. primaryandtertiaryD. tertiaryonly

Question 6Inthediagrambelow,GraphYrepresentstheenergyprofileforthereactionbetweentwogasesinasealedcontainer.Theexperimentwasrepeatedandonechangewasmadetothereactionconditions.GraphZrepresentstheenergyprofileunderthenewconditions.

reactants

productsenthalpy

Graph YGraph Z

Key

WhichoneofthefollowingpossiblechangestothereactionconditionswouldresultinthechangeintheenergyprofilefromGraphYtoGraphZ?A. Theinitialtemperatureofthegaseswashigher.B. Aninertgaswasaddedtothereactioncontainer.C. Thevolumeofthereactioncontainerwasdecreased.D. Acatalystwasaddedtothereactioncontainerwiththegases.

Question 7Whichoneofthefollowingstatementsiscorrectforanexothermicreaction?A. Theenthalpychangeispositive.B. Theactivationenergyisnegative.C. Heatenergyisabsorbedfromtheenvironment.D. Theenthalpyofthereactantsishigherthanthatoftheproducts.



Question 8AnunidentifiedorganicsubstancewiththemolecularformulaC4H8O2isfoundtoreactwithabase.Massspectrometryshowstheparentmolecularionhasamass-to-chargeratio,m/z,of88.

100

80

60

40

relativeintensity

20

0 20 40m/z

60 80 1000

Source:NISTChemistryWebBook;NISTMassSpectrometryDataCenterCollection; ©2014USSecretaryofCommerceonbehalfoftheUSA

Whichoneofthefollowingspeciesisconsistentwithapeakonthemassspectrumatm/z=45?A. [COOH]+

B. [CH3CH2O]+

C. [CH3CH2OH]+

D. [CH3CH2CH2COOH]+

Question 9Todeterminetheconcentrationofapeptideinamixtureofpeptides,whichoneofthefollowinganalyticaltechniqueswouldbeused?A. high-performanceliquidchromatographyB. thinlayerchromatographyC. paperchromatographyD. gaschromatography



Use the following information to answer Questions 10–12.Ammoniacanbesynthesisedbyreactingnitrogen,N2,gaswithhydrogen,H2,gasaccordingtothefollowingequation.

N2(g)+3H2(g)⇌2NH3(g) ΔH=–92kJmol–1

Question 10Theexpressionfortheequilibriumconstantforthisreactionis

A. NH

H N3

2 23[ ][ ][ ]

B. 2

33

2 2

NHH N[ ]

[ ][ ]

C. NH

H N3

2

23

23

[ ][ ] [ ]

D. NH

H N3

2

23

2

[ ][ ] [ ]

Question 11Ifaninertgasisaddedtotheequilibriumsystemataconstanttemperatureandaconstantvolume,theconcentrationofH2inthemixturewillA. increase.B. decrease.C. notchange.D. decreasethenincrease.

Question 12TherateatwhichequilibriumisestablishedcanbeloweredbyincreasingtheA. temperatureofthereactionmixtureataconstantvolume.B. totalvolumeofthereactionvesselataconstanttemperature.C. concentrationofthereactantsataconstanttemperature.D. pressureinthereactionvesselataconstanttemperature.

Question 13Magnesium,Mg,metalreactswithoxygen,O2,accordingtothefollowingequation.

2Mg(s)+O2(g)→2MgO(s) ΔH=–1200kJmol–1 M(Mg)=24.3gmol–1

Forthisequation,1200kJrepresentstheA. activationenergyforthereaction.B. heatenergyreleasedwhen2gofMgreacts.C. heatenergyreleasedwhen48.6gofMgreacts.D. heatenergyreleasedwhen1molofMgreacts.



Question 14100mLof0.4Mnitricacid,HNO3,isaddedto100mLof0.1Mbariumhydroxide,Ba(OH)2.ThepHoftheresultingsolutionisA. 0.3B. 0.7C. 0.8D. 1.0

Question 15Whichoneofthefollowingfactorsisleastlikelytoaffecttherateatwhichthecomponentsofagasmixtureflowthroughagaschromatographycolumn?A. thelengthofthecolumnB. thetemperatureofthecolumnC. therateofflowofthecarriergasD. themolecularmassesofthegasesinthegasmixture

Question 16

CH3CH2ClNaOH

CH3CH2OHReagent X

CH3COOHCH3CH2CH2OH

Product Z

Forthereactionpathwayshownabove,whichofthefollowingcorrectlyidentifiesReagentXandProductZ?

Reagent X Product Z

A. O2 ethylethanoate

B. H+/Cr2O72– ethylpropanoate

C. NaOH propylpropanoate

D. H+/MnO4– propylethanoate



Use the following information to answer Questions 17 and 18.ThegalvaniccellshownbelowissetupunderafumehoodbyaChemistrystudentatauniversity.Chlorinegas,Cl2,iscontinuallybubbledthroughthelefthalf-cell.

V

Pt electrode

salt bridgeCu electrode

1 M CuSO4 solution(blue, 25 °C)

Cl2(g)(1 atm, 25 °C)

1 M NaCl solution(clear, 25 °C)

Question 17WhenthecellbeginstooperateA. thecellvoltagewillstartat1.02V,thenslowlydrop.B. theCuelectrodewillhavepositivepolarityandactasthecathode.C. electronswillmoveoutofthePtelectrodeandalongthewiringtotheCuelectrode.D. electronswillmovethroughthesaltbridgetowardstheCuhalf-cellandcompletethecircuit.

Question 18WhatisthestudentmostlikelytoobserveintheCuhalf-cellsometimeaftertheswitchisturnedon?A. bubblesformingovertheelectrodeB. theCuelectrodelookingcorrodedC. thesolutionbecomingalighterblueincolourD. crystalsofCugrowingovertheelectrode



Question 19Asamplecontainingamixtureoffourstraight-chainalcohols–butanol,ethanol,hexanolandpentanol–isanalysedbygaschromatography.

detectorresponse

1 2 3retention time (min)

4 5 6

Q

Onthechromatogram,thepeakatQwasmostlikelyproducedbyA. butanol.B. ethanol.C. hexanol.D. pentanol.

Question 20Someinformationgivenonthelabelsofabottleofdisinfectantisshownbelow.

500 mL

SmileyCleanPowerful disinfectant

Active ingredient

BENZALKONIUMCHLORIDE1.5%w/w

DIRECTIONS

FOR HOSPITAL STANDARD DISINFECTION

Use undiluted

FOR GENERAL HOUSEHOLD USE

Dilute 1 part disinfectant with 20 parts water

Data• benzalkoniumchloride:C17H30ClN• density(SmileyClean):1.0gmL–1

• molarmassofC17H30ClN:283.5gmol–1

Theconcentration,inmolL–1,ofbenzalkoniumchlorideinadilutedsolutionofSmileyCleandisinfectant,readyforgeneralhouseholduse,isA. 1.5×10–2

B. 5.3×10–2

C. 2.5×10–3

D. 2.6×10–3



Question 21Thegraphbelowrepresentsthetitrationof1.0Msodiumcarbonatesolution,Na2CO3,against1.0Mhydrochloricacid,HCl.Thetitrationhastwoequivalencepoints,StageIandStageII,correspondingtotheadditionofsuccessiveprotonstothebase.

14

7pH

0

CO32–(aq)

Stage ICO3

2–(aq) + H+(aq) → HCO3–(aq)

Stage IIHCO3

–(aq) + H+(aq) → H2CO3(aq)

volume of HCl (mL)

WhichoneofthefollowingindicatorsisthemostappropriatetousetodetecttheendpointforStageII?A. phenolphthaleinB. methylorangeC. thymolblueD. phenolred



Question 22Asealedgassyringecontainsanequilibriummixtureofbrownnitrogendioxidegas,NO2,andcolourlessdinitrogentetroxidegas,N2O4.Thisisshowninthediagrambelow.

gas syringe

plungergas mixturerubber stopper

Theequationforthisequilibriumreactionis

N2O4(g)⇌2NO2(g) ΔH=+57.20kJmol–1

Theplungerissuddenlypushedinattimet1,thusdecreasingthetotalvolumeofthegasmixture.Thetemperatureofthegasmixtureiskeptconstant.Whichoneofthefollowingconcentration–timegraphsrepresentsthechangethatoccurs?

NO2

N2O4

concentration(mol L–1)

time(min)t1

NO2

N2O4


time(min)t1

NO2

N2O4


time(min)t1

NO2

N2O4


time(min)t1

A. B.

C. D.

Question 23Theequationbelowrepresentsthecompletecombustionofmethanol.

2CH3OH(l)+3O2(g)→2CO2(g)+4H2O(g)

Theheatofcombustionofmethanol,inkJg–1,isclosesttoA. 1450B. 725C. 45.31D. 22.66



Question 24NarrowstripsofMetalXwereplacedinsolutionsoffourdifferentsaltsinseparatetesttubes.Thetablebelowshowstheobservationsmadeafter10minutes.

Solution Observations

copper(II)sulfate smallreddishcrystalsformedonMetalX;bluecolourofsolutionlightenedslightly

iron(III)chloride solutionturnedfromayellowishcolourtoagreenishcolour

nickel(II)sulfate smallgreyishcrystalsformedonMetalX;greencolourofsolutionlightenedslightly

aluminiumsulfate noapparentchange

MetalXismostlikelyA. silver.B. copper.C. iron.D. nickel.

Question 25Ananalystisgivenaflaskcontaininga20.0mLsolutionof0.52Mbariumchloride,BaCl2.Sheadds 25.0mLof0.75Msulfuricacid,H2SO4.Shecollectsanddriestheresultingbariumsulfateprecipitate,BaSO4.Themassofthedriedprecipitateis2.43g.WhatistheconcentrationofSO4

2–ions,inmolL–1,inthefiltrate?A. 0.19B. 0.23C. 0.33D. 0.42

Question 26Whenethanol,C2H5OH,reactswithalimitedamountofdichromicacid,H2Cr2O7,thereactionproduceschromium(III)ions,Cr3+,andethanal,C2H4O.Whatisthebalancedhalf-equationfortheoxidationreaction?A. 2Cr2O7

2–(aq)→4Cr3+(aq)+7O2(g)+16e–

B. C2H5OH(aq)→C2H4O(aq)+2H+(aq)+2e–

C. Cr2O72–(aq)+14H+(aq)+6e– →2Cr3+(aq)+7H2O(l)

D. 3C2H5OH(aq)+Cr2O72–(aq)+8H+(aq)→2Cr3+(aq)+3C2H4O(aq)+7H2O(l)

2017 CHEMISTRY EXAM (NHT) 12


Question 27An electric current is passed through water to which a very small amount of sodium chloride, NaCl, has been added. The electrolytic cell is shown in the diagram below.

C electrode(graphite)

C electrode (graphite)

H2O(1)NaCl(aq)

The net cell reaction is

2H2O(l) → 2H2(g) + O2(g)

Which one of the following statements applies to this electrolytic cell as it operates?A. H2O will be the reactant at each electrode.B. The rate of bubbling will be the same at each electrode.C. H2 gas will be produced at the anode and O2 gas will be produced at the cathode.D. For each mole of electrons passed through the cell, 1 mol of H2 gas will be collected.

13 2017 CHEMISTRY EXAM (NHT)


Use the following information to answer Questions 28 and 29.As part of an investigation into silver plating, a group of students wants to coat a metal object with silver, Ag, by electrolysis. They set up a simple electrolytic cell using silver nitrate, AgNO3, solution, as shown in the diagram below.

power supply

Agelectrode

metalobjectto be plated

AgNO3 solution

Question 28Which one of the following statements is correct?A. During the electrolysis, the concentration of the AgNO3 solution will not change.B. During the electrolysis, each gram of Ag deposited will require 1 mol of electrons.C. During the electrolysis, water will be the reactant at the Ag electrode.D. During the electrolysis, the Ag electrode will have negative polarity.

Question 29A total of 0.75 g of Ag is required to plate the metal object.The electrolytic cell is first operated at 0.75 A for 10 minutes. The current is then changed to 1.00 A.For how much longer would the cell need to operate to complete the plating?A. 71 sB. 220 sC. 450 sD. 670 s


END OF SECTION A

Question 30Primarycells,secondarycellsandfuelcellscanallbeusedassourcesofenergy.Thefeaturesthatcanbeassociatedwithoneormoreofthethreetypesofcellsincludethefollowing:1. Thecellisrechargeable.2. Thecellrequiresacontinuoussupplyofreactants.3. Reductiontakesplaceatthecathodewhendischarging.4. Oxidationtakesplaceatthepositiveelectrodewhenrecharging.

Whichoftheabovefeaturesaredisplayedbysecondarycells?A. 1,2and3B. 2,3and4C. 1,3and4D. 1,2,3and4


SECTION B – continuedTURN OVER

SECTION B

Instructions for Section BAnswerallquestionsinthespacesprovided.Writeusingblueorblackpen.Toobtainfullmarksforyourresponses,youshould:• givesimplifiedanswers,withanappropriatenumberofsignificantfigures,toallnumericalquestions;

unsimplifiedanswerswillnotbegivenfullmarks• showallworkinginyouranswerstonumericalquestions;nomarkswillbegivenforanincorrect

answerunlessitisaccompaniedbydetailsoftheworking• makesurechemicalequationsarebalancedandthattheformulasforindividualsubstancesincludean

indicationofstate;forexample,H2(g),NaCl(s).Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.


SECTION B – Question 1–continued

Question 1 (7marks)a. CompoundCmaybesynthesisedaccordingtothefollowingpathway.

CC

Cl

CH3

H

H

CH3

H

Compound A

Compound B

Compound C

Structural formula:

Name:

Name:

Semi-structural formula:

HCl(g)/catalyst

NH3 (ethanol)

i. DrawthestructuralformulaofCompoundAintheboxprovided. 1mark

ii. WritethesystematicnameofCompoundBintheboxprovided. 1mark

iii. Insertthesemi-structuralformulaandsystematicnameofCompoundCintheboxprovided. 2marks



b. Butan-1-ol,C4H9OH,canreactwithacidifiedpermanganateions,MnO4–,toproducebutanoic

acid,C3H7COOH.

i. Writeabalancedredoxhalf-equationfortheproductionofC3H7COOHfromC4H9OH. 1mark

ii. C3H7COOHreactswithethanol,C2H5OH,inthepresenceofsulfuricacid,H2SO4.

Nametheproductformed. 1mark

iii. Drawthestructuralformulaoftheproductnamedinpart b.ii. 1mark



Question 2 (7marks)Glutathioneisatripeptidethatisfoundinthehumanbody.Itactsasanantioxidant,helpingtopreventdamagetocells.Thesequenceforthistripeptideisglu-cys-gly.

a. Drawastructurethatrepresentsthissequenceofaminoacids,clearlyshowingthelinkagesbetweentheaminoacids. 3marks

b. Glutamicacidcanbeisolatedfromasampleofglutathione.

Drawastructureofglutamicacidina1.0Msodiumhydroxidesolution. 2marks



c. Inhumanbodycells,glutathioneisoxidisedtoglutathionedisulfide.Thisreactionisreversedinthepresenceoftheenzymeglutathionereductase.Thisenzymeworksoptimallyatbodytemperature.

Explainwhyglutathionereductasewouldnotbeeffectiveathighertemperatures. 2marks



Question 3 (6marks)AcompoundhasthemolecularformulaC5H10O2.Itisanalysedbyinfrared(IR),

13CNMRand1HNMRspectroscopy.Theresultingspectraareshownbelow.

100

50transmittance

(%)

04000 3000 2000 1500

wave number (cm–1)1000 500

IR spectrum

Data:SDBSWeb,http://sdbs.db.aist.go.jp, NationalInstituteofAdvancedIndustrialScienceandTechnology

ppm200 180 160 140 120 100 80 60 40 20 0

13C NMR spectrum


9 8 7 6 5ppm

4 3 2 1 0

1H NMR spectrum




Informationforthesplittingpatternofthe1HNMRspectrumisshownbelow.

Chemical shift Relative peak area Splitting pattern

4.1 2 4peaks

2.3 2 4peaks

1.3 3 3peaks

1.1 3 3peaks

a. UsingtheIRspectrumprovided,identifyabondinamoleculeofC5H10O2andgiveitswavenumber. 1mark

b. Usingthe1HNMRspectrumprovided,statethenumberofhydrogenenvironmentsinamoleculeofC5H10O2. 1mark

c. WhatspecificinformationaboutthestructureofamoleculeofC5H10O2isprovidedbythesplittingpatterninthe1HNMRspectrum? 1mark

d. DrawastructureconsistentwiththedataprovidedforamoleculeofC5H10O2.Explainhowthestructureyouhavedrawnissupportedbyevidencefromthe13CNMRspectrum,whichcontainsfivepeaks. 3marks



Question 4 (6marks)TheBradfordproteinassayisaspectroscopicmethodofdeterminingtheconcentrationofproteinsinasolution.TheBradfordproteinassayusesacidifiedCoomassieBluedye(G-250),whichchangesfrombrowntobrilliantbluewhenitbindstoproteinsinasolution.Theintensityofthebluecolourofthedyeincreasesastheconcentrationofproteinsinthesolutionincreases.TheabsorptionspectrausedfortheBradfordproteinassayareshowninthegraphbelow.

400 450 500 550wavelength (nm)

600 650

465 nm 595 nm520 nm 650 nm0.8

0.7

0.6

0.5

0.4absorbance

0.3

0.2

0.1

0.0

Coomassie Blue dye

Coomassie Blue dye (bound to protein)

Key

a. NamethetypeofspectroscopyusedintheBradfordproteinassay. 1mark

b. Whatwavelengthwouldbemostappropriatetodeterminetheconcentrationofproteinsinasolution?Justifyyouranswer. 2marks



c. The Bradford protein assay was used to determine the concentration of proteins in a liver cell extract. • Equalvolumesofstandardsolutionsofproteinswereprepared.Thesamevolumeofdye

was added to each one.• Thespectrometerwasadjustedtoreadzeroabsorbanceforthe0µg mL–1 standard.• Theabsorbanceofeachofthestandardsolutionswasmeasuredandthedatawasplottedon

a graph. Thegraphbelowshowsthecalibrationcurveforabsorbanceasafunctionoftheconcentration

of proteins.

0.90

0.80

0.70

0.60

0.50absorbance

0.40

0.30

0.20

0.10

0.00 1000 200 300 400concentration of proteins (µg mL–1)

500 600 700 800

Priortoitsabsorbancebeingmeasured,1.50mLofthelivercellextractwasmadeupto10.00mLwithabuffersolution.Usingthesameequipmentwiththesamesettings,theabsorbanceofthedilutedsampleofthelivercellextractwasmeasuredas0.28

i. What is the concentration of proteins in the diluted sample of the liver cell extract? 1 mark

ii. Calculatetheconcentration,inmgmL–1,ofproteinsintheundilutedsampleofthelivercell extract. 2 marks



Question 5 (8marks)Somestudentssetupa‘lemonbattery’experimentusingfreshlysandedstripsofcopper,Cu,andiron,Fe,astheelectrodes.Thestudentsclosedtheswitch,measuredthevoltageanddeterminedthedirectionoftheflowofelectronsintheexternalcircuit.Adiagramdepictingtheirexperimentandatableoftheirresultsareshownbelow.

V

strip of Cu(Cu electrode)

strip of Fe(Fe electrode)

lemon

globe

voltmeter

Results

voltage 0.35V

movementofelectrons fromFetoCu

a. LemonjuicecanbeconsideredasanaqueoussolutionofH+ions.

Writebalancedhalf-equationsforthereactionsattheelectrodesinthecopper-ironlemonbattery. 2marks

• Cuelectrode

• Feelectrode

b. Identifytheelectrodethatactsasthecathode. 1mark

c. i. Usingtheelectrochemicalseries,statethetheoreticalvoltageforthislemonbattery. 1mark

ii. Explainwhytheexperimentalvalueofthevoltageisdifferentfromthetheoreticalvoltage. 2marks



d. The Cu electrode in the lemon battery is replaced with a freshly sanded strip of aluminium, Al.

Forthisaluminium-ironlemonbattery,statetheexpecteddirectionofelectronflow.Justifyyour answer. 2 marks



Question 6 (13marks)Ethanoicacid,CH3COOH,istheactiveingredientinwhitevinegar.AsampleofwhitevinegarisanalysedtoaccuratelydeterminetheconcentrationofCH3COOHusingthefollowingsteps:Step1–Dilutea10.00mLsampleofthewhitevinegarto100.00mLinavolumetricflask.Step2–Rinsetheburettewiththestandardisedsodiumhydroxidesolution,NaOH,thatis

provided.Step3–FilltheburettewiththestandardisedNaOHsolution.Step4–Pipette20.00mLofthedilutedwhitevinegarsolutionintoa250mLconicalflask.Step5–Addseveraldropsofphenolphthaleinindicatortotheconicalflask.Titratethediluted

whitevinegarsolutionagainstthestandardisedNaOHsolution.Step6–RepeatSteps3–5untilconcordantresultsareobtained.

Theequationforthisanalysisis

CH3COOH(aq) +NaOH(aq)→CH3COONa(aq) + H2O(l)

Data

aliquotofdilutedwhitevinegarsolution 20.00mL

meantitreofNaOHsolution 25.60mL

concentrationofstandardisedNaOHsolution 0.1123M

a. i. CalculatetheconcentrationofCH3COOHintheundilutedwhitevinegarsample. 3marks

ii. IftheburetteisrinsedwithwaterinsteadofthestandardisedNaOHsolution,whatwouldbetheeffect,ifany,ontheexperimentalvalueobtainedfortheconcentrationofCH3COOHinwhitevinegar?Justifyyouranswer. 2marks



b. CH3COOHisaweakacid.

i. WritetheequationfortheionisationofCH3COOHinwater. 1mark

ii. WritetheexpressionfortheacidityconstantforCH3COOH. 1mark

c. AnalternativemethodofdeterminingtheconcentrationofCH3COOHinwhitevinegaristomeasurethepHofthevinegar.

Inanotherexperiment,thepHoftheundilutedwhitevinegarsampleisfoundtobe2.29usingacalibrateddigitalpHprobe.

CalculatetheconcentrationofCH3COOHintheundilutedwhitevinegarsampleusingthepHvalueprovided. 2marks

d. SuggestanexplanationforanydifferenceintheresultsobtainedfortheconcentrationofCH3COOHfromthetwodifferentexperiments. 2marks

e. AsolutionofCH3COOHisdiluted.

Whateffect,ifany,wouldthishaveonthepercentageionisationofCH3COOH?Justifyyouranswer. 2marks



Question 7 (7marks)Moltencarbonatefuelcells(MCFCs)canbeusedasastationaryenergysource.Theyoperateattemperaturesbetween600°Cand700°C.TheelectrolyteinanMCFCistypicallyamoltenmixtureoflithium,sodiumorpotassiumcarbonates.AsimplifieddiagramofanMCFCisshownbelow.

molten electrolyteCO3

2–

direction of electron flow

polarity polarity

porouselectrodes

H2(g)

H2O(g)CO2(g)

O2(g)CO2(g)

unreactedO2(g), CO2(g)

AtoneelectrodeoftheMCFC,carbondioxide,CO2,gasreactswithoxygen,O2,gastoformcarbonateions.Attheotherelectrode,hydrogen,H2,gasreactswithmoltencarbonateionstoformsteamandCO2gas.

a. Onthediagramabove

i. labelthepolarityoftheelectrodesinthecirclesprovided 1mark

ii. showthedirectionofelectronflowintheexternalcircuitbydrawinganarrowintheboxabovethecell. 1mark

b. Onasmallscale,electricitycanbegeneratedinavarietyofways.

WhatisoneadvantageofproducingelectricityfromanMCFCratherthanfromapetrolgenerator? 1mark



c. i. Writeabalancedhalf-equationfortheproductionofcarbonateionsfromCO2andO2. 1mark

ii. CalculatethevolumeofO2gas,at665°Cand2.50atm,neededtoproduce11.50molofcarbonateions. 3marks



Question 8 (10marks)a. Writethebalancedthermochemicalequationforthecompletecombustionofmethane. 2marks

b. Completeandlabeltheincompletediagramprovidedbelowtoshowtheenergyprofileforthecombustionofmethane.LabeltheΔH,activationenergyEaandtheproducts. 3marks

0enthalpy reactants

c. Asampleofbiogascontains78.0%,bymass,ofmethane.Thisbiogasisburntasasourceofenergy.

Calculatethemaximumamountofenergy,inkilojoules,thatcouldbeproducedfromthecombustionofthemethanepresentin100kgofthisbiogas. 3marks



d. Identifyoneadvantageandonedisadvantageofusingbiogasasanenergysource. 2marks

Advantage

Disadvantage



Question 9 (13marks)Whencolourlesshydrogen,H2 ,gasandpurpleiodine,I2 ,gasaremixedathightemperatures,theyreacttoproducecolourlesshydrogeniodide,HI.Thisreactiondoesnotgotocompletionbutinsteadformsanequilibriummixture.Theequationforthereactionisshownbelow.

H2(g) + I2(g) ⇌ 2HI(g) ΔH=positive

colourless purple colourless

a. AchemistinjectsequalamountsofH2gasandI2gasintoaninsulated,evacuatedandsealed1.0Lcontainertowhichatemperatureprobeisattached.Bothgasesandthecontainerhadaninitialtemperatureof250°C.Thechemist’sobservationsoverthenexthourareshowninthetablebelow.

Observations

Time from moment of mixing (min)

Temperature (°C) Colour of gas mixture

0 250 darkpurple

15 239 purple

30 232 palepurple

45 232 palepurple(nofurtherchange)

60 232 palepurple(nofurtherchange)

Explainwhytheinitialdark-purplecolourofthegasmixturelightenstopalepurpleandthenremainsunchanged. 2marks

b. Identifyonechangethatcouldbemadetotheoriginalreaction’sconditionssothatequilibriumisreachedatafasterrate.Justifyyouranswer. 2marks



c. Thechemistperformsthreeteststoobservehowtheequilibriummixturerespondstochange.

Predicttheeffectofeachofthefollowingchangesonthecolourofthegasmixtureasitwasafter60minutes.Justifyyouranswers. 9marks

• Heatthegasmixturetoaconstant280°C.Assumethevolumeremainsconstant.

Circlethepredictedeffectonthecolourofthegasmixture.

darker lighter unchanged

Justification

• Restorethetemperatureofthegasmixtureto232°C.Increasethevolumeofthecontainerto1.5Lataconstanttemperatureof232°C.



Justification

• Restorethevolumeofthecontainerto1.0L.InjectsomeHIintothecontainerataconstanttemperatureof232°C.



Justification



Question 10 (7marks)Abombcalorimeteriscalibratedusinganelectricalheater.Thedataforthecalibrationisgivenin Table1.

Table 1

initialtemperatureofthewater 22.53°C

finaltemperatureofthewater 25.23°C

currentsupplied 4.50A

voltagesupplied 5.80V

time 300s

a. UsethedatainTable1tocalculatethecalibrationfactorforthebombcalorimeter.StateyouranswerinkJ°C–1. 2marks

b. Methyllaurate(methyldodecanoate),C13H26O2,isacomponentofsomebiodieselsandisaliquidatroomtemperature.ThepreviouslycalibratedbombcalorimeterisusedtodeterminethemolarenthalpyofC13H26O2.

AsampleofC13H26O2isinjectedintothebombcalorimeterandthenburntinexcessoxygen. ThedataforthisexperimentisgiveninTable2.

Table 2

initialtemperatureofthewater 23.83°C

finaltemperatureofthewater 35.15°C

massofC13H26O2 0.905g

molarmassofC13H26O2 214.0gmol–1

Calculatetheamountofenergyreleased,inkilojoules,whenthesampleofC13H26O2wasburnt. 1mark



c. CalculatethemolarenthalpyofcombustionofC13H26O2 usingthedatafromthisexperiment. 3marks

d. Hence,completethefollowingbalancedequationforthecombustionofC13H26O2inexcessoxygen. 1mark

2C13H26O2(l)+37O2(g)→26CO2(g) +26H2O(g) ΔH=



Question 11 (6marks)AChemistryclasswasaskedtodeterminethesodiumcontentofaparticularbrandofpotatochipsbygravimetricanalysis.Theclass’resultswouldthenbecomparedwiththesodiumcontentstatedonthelabelonthepacketofpotatochips,whichwas‘sodium644mg/100g’.ThefollowingisanextractfromthelogbookofaparticularpairofstudentsidentifiedasPairA.

Procedure1. Approximately10gofpotatochipswereweighedandthencrushedwithamortarandpestle.2. Theoilymixturewastransferredtoabeakerandapproximately30mLofwaterwasadded.3. Afterstirring,themixturewastransferredtoaseparatingfunnel.Themixturewasshakenfor

twominutesandallowedtosettle.4. Thewaterlayerwasdrained,thenfiltered.Theresiduewaswashed.5. AgNO3solutionwasaddedtothefiltrateuntilnomoreAgClprecipitatewasobservedtoform.6. TheAgClprecipitatewasfiltered,rinsedanddried.7. TheAgClprecipitatewasscrapedoffthefilterpaperandintoabottle,thenweighed.

EquationNaCl(aq)+AgNO3(aq)→AgCl(s)+NaNO3(aq)

Results

massofpotatochips 9.832g

massofdriedAgCl 0.417g

Calculationsn(AgCl)=0.417/143.4mol=0.00291molThusn(Na+)=0.00291molHencem(Na+)in9.832gofpotatochips=0.00291×23.0=0.0669gSom(NaCl)in100gofpotatochips=0.0669×100/9.832g=1.73gAndm(Na)=1.73/58.5×23.0g/100g=0.680g/100g

Theresultsfortheentireclasswererecordedasfollows.

Pair A B C D E F G

Mass Na(g/100 g) 0.680 0.704 0.221 0.731 0.979 0.649 0.712


Analyseandevaluatetheexperimentaldesignandtheclass’results.Inyourresponse,youshould:• commentononeassumptionthathasbeenmadeinconductingthisexperiment• suggestamodificationthatcouldbemadetotheexperimentaldesignandjustifyyouranswer• commentontheconclusionsthatmightbedrawnfromtheclass’results• comparetheresultsobtainedwiththemanufacturer’sclaimandsuggestareasonforanydifference.

END OF QUESTION AND ANSWER BOOK

Instructions

• Aquestionandanswerbookisprovidedwiththisdatabook.

Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room.

CHEMISTRYWritten examination

Wednesday 7 June 2017 Reading time: 10.00 am to 10.15 am (15 minutes) Writing time: 10.15 am to 12.45 pm (2 hours 30 minutes)

DATA BOOK

©VICTORIANCURRICULUMANDASSESSMENTAUTHORITY2017

Victorian Certificate of Education 2017

2017CHEMISTRYDATABOOK 2

Table of contents Page

1. Periodictableoftheelements 3

2. Theelectrochemicalseries 4

3. Physicalconstants 5

4. SIprefixes,theirsymbolsandvalues 5

5. 1HNMRdata 5–6

6. 13CNMRdata 7

7. Infraredabsorptiondata 7

8. 2-aminoacids(α-aminoacids) 8–9

9. Formulasofsomefattyacids 10

10. Structuralformulasofsomeimportantbiomolecules 10

11. Acid-baseindicators 11

12. Acidityconstants,Ka,ofsomeweakacidsat25°C 11

13. Valuesofmolarenthalpyofcombustionofsomecommonfuelsat298Kand101.3kPa 11

3 2017CHEMISTRYDATABOOK

TURN OVER

1. P

erio

dic t

able

of t

he el

emen

ts

1 H

1.0

hydrogen

2 He

4.0

helium

3 Li

6.9

lithium

4 Be

9.0

beryllium

5 B

10.8

boron

6 C

12.0

carbon

7 N

14.0

nitrogen

8 O

16.0

oxygen

9 F 19.0

fluorine

10

Ne

20.2

neon

11

Na

23.0

sodium

12

Mg

24.3

magnesium

13

Al

27.0

alum

inium

14

Si

28.1

silicon

15

P 31.0

phosphorus

16

S 32.1

sulfur

17

Cl

35.5

chlorine

18

Ar

39.9

argon

19

K

39.1

potassium

20

Ca

40.1

calcium

21

Sc

45.0

scandium

22

Ti

47.9

titanium

23

V

50.9

vanadium

24

Cr

52.0

chromium

25

Mn

54.9

manganese

26

Fe

55.8

iron

27

Co

58.9

cobalt

28

Ni

58.7

nickel

29

Cu

63.5

copper

30

Zn

65.4

zinc

31

Ga

69.7

gallium

32

Ge

72.6

germanium

33

As

74.9

arsenic

34

Se

79.0

selenium

35

Br

79.9

brom

ine

36

Kr

83.8

krypton

37

Rb

85.5

rubidium

38

Sr

87.6

strontium

39

Y

88.9

yttrium

40

Zr

91.2

zirconium

41

Nb

92.9

niobium

42

Mo

96.0

molybdenum

43

Tc

(98)

technetium

44

Ru

101.1

ruthenium

45

Rh

102.9

rhodium

46

Pd

106.4

palladium

47

Ag

107.9

silver

48

Cd

112.4

cadm

ium

49

In

114.8

indium

50

Sn

118.7

tin

51

Sb

121.8

antim

ony

52

Te

127.6

tellurium

53

I 126.9

iodine

54

Xe

131.3

xenon

55

Cs

132.9

caesium

56

Ba

137.3

barium

57–7

1 lanthanoids

72

Hf

178.5

hafnium

73

Ta

180.9

tantalum

74

W

183.8

tungsten

75

Re

186.2

rhenium

76

Os

190.2

osmium

77

Ir

192.2

iridium

78

Pt

195.1

platinum

79

Au

197.0

gold

80

Hg

200.6

mercury

81

Tl

204.4

thallium

82

Pb

207.2

lead

83

Bi

209.0

bism

uth

84

Po

(210)

polonium

85

At

(210)

astatine

86

Rn

(222)

radon

87

Fr

(223)

francium

88

Ra

(226)

radium

89–1

03

actinoids

104

Rf

(261)

rutherfordium

105

Db

(262)

dubnium

106

Sg

(266)

seaborgium

107

Bh

(264)

bohrium

108

Hs

(267)

hassium

109

Mt

(268)

meitnerium

110

Ds

(271)

darmstadtium

111

Rg

(272)

roentgenium

112

Cn

(285)

copernicium

114

Fl

(289)

flerovium

116

Lv

(292)

livermorium

57

La

138.9

lanthanum

58

Ce

140.1

cerium

59

Pr

140.9

praseodymium

60

Nd

144.2

neodym

ium

61

Pm

(145)

prom

ethium

62

Sm

150.4

samarium

63

Eu

152.0

europium

64

Gd

157.3

gadolinium

65

Tb

158.9

terbium

66

Dy

162.5

dysprosium

67

Ho

164.9

holmium

68

Er

167.3

erbium

69

Tm

168.9

thulium

70

Yb

173.1

ytterbium

71

Lu

175.0

lutetium

89

Ac

(227)

actinium

90

Th

232.0

thorium

91

Pa

231.0

protactinium

92

U

238.0

uranium

93

Np

(237)

neptunium

94

Pu

(244)

plutonium

95

Am

(243)

americium

96

Cm

(247)

curium

97

Bk

(247)

berkelium

98

Cf

(251)

californium

99

Es

(252)

einsteinium

100

Fm

(257)

fermium

101

Md

(258)

mendelevium

102

No

(259)

nobelium

103

Lr

(262)

lawrencium

Thevalueinbracketsindicatesthemassn

umberofthelongest-livedisotope.

79

Au

197.0

gold

atom

icnum

ber

relativeatom

icmass

symbolofelement

nameofelement


2. The electrochemical series

Reaction Standard electrode potential (E0) in volts at 25 °C

F2(g)+2e–⇌ 2F–(aq) +2.87

H2O2(aq)+2H+(aq)+2e–⇌ 2H2O(l) +1.77

Au+(aq)+e–⇌ Au(s) +1.68

Cl2(g)+2e–⇌ 2Cl–(aq) +1.36

O2(g)+4H+(aq)+4e–⇌ 2H2O(1) +1.23

Br2(l)+2e–⇌ 2Br–(aq) +1.09

Ag+(aq)+e–⇌ Ag(s) +0.80

Fe3+(aq)+e–⇌ Fe2+(aq) +0.77

O2(g)+2H+(aq)+2e–⇌ H2O2(aq) +0.68

I2(s)+2e–⇌ 2I–(aq) +0.54

O2(g)+2H2O(l)+4e–⇌ 4OH–(aq) +0.40

Cu2+(aq)+2e–⇌ Cu(s) +0.34

Sn4+(aq)+2e–⇌ Sn2+(aq) +0.15

S(s)+2H+(aq)+2e–⇌ H2S(g) +0.14

2H+(aq)+2e–⇌ H2(g) 0.00

Pb2+(aq)+2e–⇌ Pb(s) –0.13

Sn2+(aq)+2e–⇌ Sn(s) –0.14

Ni2+(aq)+2e–⇌ Ni(s) –0.23

Co2+(aq)+2e–⇌ Co(s) –0.28

Fe2+(aq)+2e–⇌ Fe(s) –0.44

Zn2+(aq)+2e–⇌ Zn(s) –0.76

2H2O(l)+2e–⇌ H2(g)+2OH–(aq) –0.83

Mn2+(aq)+2e–⇌ Mn(s) –1.03

Al3+(aq)+3e–⇌ Al(s) –1.67

Mg2+(aq)+2e–⇌ Mg(s) –2.34

Na+(aq)+e–⇌ Na(s) –2.71

Ca2+(aq)+2e–⇌ Ca(s) –2.87

K+(aq)+e–⇌ K(s) –2.93

Li+(aq)+e–⇌ Li(s) –3.02


TURN OVER

3. Physical constants

Avogadro’sconstant(NA) 6.02×1023mol–1

chargeononeelectron –1.60×10–19C

Faradayconstant(F) 96500Cmol–1

gasconstant(R) 8.31JK–1mol–1

ionicproduct(self-ionisationconstant)forwater(Kw)at298K 1.00×10–14mol2L–2

molarvolume(Vm)ofanidealgasat273K,101.3kPa(STP) 22.4Lmol–1

molarvolume(Vm)ofanidealgasat298K,101.3kPa(SLC) 24.5Lmol–1

specificheatcapacity(c)ofwater 4.18Jg–1K–1

density(d)ofwaterat25°C 1.00gmL–1

1atm 101.3kPa=760mmHg

0°C 273K

4. SI prefixes, their symbols and values

SI prefix Symbol Value

giga G 109

mega M 106

kilo k 103

deci d 10–1

centi c 10–2

milli m 10–3

micro μ 10–6

nano n 10–9

pico p 10–12

5. 1H NMR dataTypicalprotonshiftvaluesrelativetoTMS=0Thesecandifferslightlyindifferentsolvents.Wheremorethanoneprotonenvironmentisshownintheformula,theshiftreferstotheonesinboldletters.

Type of proton Chemical shift (ppm)

R–CH3 0.8–1.0

R–CH2–R 1.2–1.4

RCH=CH–CH3 1.6–1.9

R3–CH 1.4–1.7


Type of proton Chemical shift (ppm)

or CH3

ORC

OCH3

NHR

CO

2.0

CH3R

C

O

2.1–2.7

R–CH2–X(X=F,Cl,BrorI) 3.0–4.5

R–CH2–OH,R2–CH–OH 3.3–4.5

R

NHCH2R

CO

3.2

R—O—CH3 or R—O—CH2R 3.3

O C

O

CH32.3

R

OCH2R

CO

4.1

R–O–H 1–6(variesconsiderablyunderdifferentconditions)

R–NH2 1–5

RHC CH2 4.6–6.0

OH 7.0

H 7.3

R

NHCH2R

CO

8.1

R

H

CO

9–10

R

OC

H

O9–13


TURN OVER

6. 13C NMR data

Type of carbon Chemical shift (ppm)

R–CH3 8–25

R–CH2–R 20–45

R3–CH 40–60

R4–C 36–45

R–CH2–X 15–80

R3C–NH2 35–70

R–CH2–OH 50–90

RC CR 75–95

R2C=CR2 110–150

RCOOH 160–185

7. Infrared absorption dataCharacteristicrangeforinfraredabsorption

Bond Wave number (cm–1)

C–Cl 700–800

C–C 750–1100

C–O 1000–1300

C=C 1610–1680

C=O 1670–1750

O–H(acids) 2500–3300

C–H 2850–3300

O–H(alcohols) 3200–3550

N–H(primaryamines) 3350–3500


8. 2-amino acids (α-amino acids)

Name Symbol Structure

alanine Ala

H2N CH COOH

CH3

arginine Arg

H2N CH COOH

CH2 CH2 CH2 NH

NH

C NH2

asparagine Asn

H2N CH COOH

CH2

O

C NH2

asparticacid Asp

H2N CH COOH

CH2 COOH

cysteine Cys

H2N CH COOH

CH2 SH

glutamine Gln

H2N CH COOH

CH2 CH2

O

C NH2

glutamicacid Glu

H2N CH COOH

CH2 CH2 COOH

glycine Gly H2N CH2 COOH

histidine His

H2N CH COOH

CH2 NH

N

isoleucine Ile

H2N CH COOH

CH3 CH CH2 CH3


TURN OVER

Name Symbol Structure

leucine Leu

H2N CH COOH

CH2

CH3 CH CH3

lysine Lys

H2N CH COOH

CH2 CH2 CH2 CH2 NH2

methionine Met

H2N CH COOH

CH2 CH2 S CH3

phenylalanine Phe

H2N CH

CH2

COOH

proline ProHN

COOH

serine Ser

H2N CH COOH

CH2 OH

threonine Thr

H2N CH COOH

CH3 CH OH

tryptophan Trp

H2N CH

CH2

COOH

HN

tyrosine Tyr OH

H2N CH

CH2

COOH

valine Val

H2N CH COOH

CH3 CH CH3


9. Formulas of some fatty acids

Name Formula

lauric C11H23COOH

myristic C13H27COOH

palmitic C15H31COOH

palmitoleic C15H29COOH

stearic C17H35COOH

oleic C17H33COOH

linoleic C17H31COOH

linolenic C17H29COOH

arachidic C19H39COOH

arachidonic C19H31COOH

10. Structural formulas of some important biomolecules

OH

OH

OH

OH HO

O O

O

H H

H

H H

H

H H

CH2OH

CH2OH

HOCH2

sucrose

OH

HO

O

H H H H

H

HOCH2

deoxyribose phosphate

O

O

P OO

C

C

C

H

H

OH

OH

OH

H

H

H

glycerol

adenine guanine cytosine thymine

NH2 NH2

CC

CCH

CH

C

CCHC

HN HN

H2N

N N

N

C C

CO

C N N

O

C

C

O

ONH

CH

CH3CH

CHNH

NHN

HN


END OF DATA BOOK

11. Acid-base indicators

Name pH range Colour change Ka

Acid Basethymolblue 1.2–2.8 red yellow 2×10–2

methylorange 3.1–4.4 red yellow 2×10–4

bromophenolblue 3.0–4.6 yellow blue 6×10–5

methylred 4.2–6.3 red yellow 8×10–6

bromothymolblue 6.0–7.6 yellow blue 1×10–7

phenolred 6.8–8.4 yellow red 1×10–8

phenolphthalein 8.3–10.0 colourless red 5×10–10

12. Acidity constants, Ka, of some weak acids at 25 °C

Name Formula Ka

ammoniumion NH4+ 5.6×10–10

benzoic C6H5COOH 6.4×10–5

boric H3BO3 5.8×10–10

ethanoic CH3COOH 1.7×10–5

hydrocyanic HCN 6.3×10–10

hydrofluoric HF 7.6×10–4

hypobromous HOBr 2.4×10–9

hypochlorous HOCl 2.9×10–8

lactic HC3H5O3 1.4×10–4

methanoic HCOOH 1.8×10–4

nitrous HNO2 7.2×10–4

propanoic C2H5COOH 1.3×10–5

13. Values of molar enthalpy of combustion of some common fuels at 298 K and 101.3 kPa

Substance Formula State ΔHc(kJ mol–1)hydrogen H2 g –286carbon(graphite) C s –394methane CH4 g –889ethane C2H6 g –1557propane C3H8 g –2217butane C4H10 g –2874pentane C5H12 1 –3509hexane C6H14 1 –4158octane C8H18 1 –5464ethene C2H4 g –1409methanol CH3OH 1 –725ethanol C2H5OH 1 –13641-propanol CH3CH2CH2OH 1 –20172-propanol CH3CHOHCH3 1 –2003glucose C6H12O6 s –2816

2017 chemistry-nht written examination 2€¦ · d. 3-chloropentane. section a – multiple-choice...

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