2017 chem-nht-w - Exam PDF

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SUPERVISOR TO ATTACH PROCESSING LABEL HERE

Victorian Certificate of Education 2017

Letter STUDENT NUMBER

CHEMISTRY Written 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 book Section

Number of questions

Number of questions to be answered

A B

30 11

30 11

Number of marks

30 90 Total 120

• Studentsarepermittedtobringintotheexaminationroom:pens,pencils,highlighters,erasers, sharpeners,rulersandonescientificcalculator. • StudentsareNOTpermittedtobringintotheexaminationroom:blanksheetsofpaperand/or correctionfluid/tape. Materials supplied • Questionandanswerbookof37pages. • Databook. • Answersheetformultiple-choicequestions. Instructions • Writeyourstudent numberinthespaceprovidedaboveonthispage. • Checkthatyourname andstudent numberasprintedonyouranswersheetformultiple-choice questionsarecorrect,andsignyournameinthespaceprovidedtoverifythis. • Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale. • AllwrittenresponsesmustbeinEnglish. At the end of the examination • Placetheanswersheetformultiple-choicequestionsinsidethefrontcoverofthisbook. • Youmaykeepthedatabook. Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room. ©VICTORIANCURRICULUMANDASSESSMENTAUTHORITY2017

2017CHEMISTRYEXAM(NHT)

2

SECTION A – Multiple-choice questions Instructions for Section A Answerall questionsinpencilontheanswersheetprovidedformultiple-choicequestions. Choosetheresponsethatiscorrect orthatbest answers thequestion. Acorrectanswerscores1;anincorrectanswerscores0. Markswillnotbedeductedforincorrectanswers. Nomarkswillbegivenifmorethanoneansweriscompletedforanyquestion. Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.

Question 1 Thediagrambelowrepresentsaparticularacid-basetitration. 14

pH 7

0

25 volume of titrant added (mL)

Whichoneofthefollowingstatementsaboutthistitrationiscorrect? A. Attheequivalencepoint,thepHofthesolutioniscloseto4.5 B. Asolutionofastrongbasehasbeendeliveredbytheburette C. Phenolphthaleinisasuitableindicatorforthisreaction D. Thetitrantisasolutionofaweakacid Question 2 Manganesecanexistinseveraloxidationstates. Inwhichcompoundismanganeseinitshighestoxidationstate? A. Mn2O3 B. KMnO4 C. MnCO3 D. MnO(OH) Question 3 ThesystematicnameofCH3C(CH3)ClCH2CH3is A. 1-chloro-1,1-dimethylpropane. B. 3-chloro-3-methylbutane. C. 2-chloro-2-methylbutane. D. 3-chloropentane.

SECTION A – continued

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3

2017CHEMISTRYEXAM(NHT)

Question 4 Sodiumhydroxide,NaOH,solutionscarefullypreparedfromanalytical-gradeNaOHpelletscannotbeused asprimarystandardsinacid-basetitrations. Thisisbecause A. theNaOHsolutionspreparedarecolourless. B. strongbasesarecausticandcancausechemicalburns. C. theNaOHpelletsaretoodifficulttoputintovolumetricflasks. D. theexactconcentrationoftheNaOHsolutionsmadefromthepelletsisunknown. Question 5 Apureproteinsampleismixedwithdiluteacidat25°C. Whichstructure(s)oftheproteinislikelytobedisrupted? A. primaryandsecondary B. secondaryandtertiary C. primaryandtertiary D. tertiaryonly Question 6 Inthediagrambelow,GraphYrepresentstheenergyprofileforthereactionbetweentwogasesinasealed container. Theexperimentwasrepeatedandonechangewasmadetothereactionconditions. GraphZrepresentstheenergyprofileunderthenewconditions. Key Graph Y Graph Z products

enthalpy

reactants

Whichoneofthefollowingpossiblechangestothereactionconditionswouldresultinthechangeinthe energyprofilefromGraphYtoGraphZ? A. Theinitialtemperatureofthegaseswashigher. B. Aninertgaswasaddedtothereactioncontainer. C. Thevolumeofthereactioncontainerwasdecreased. D. Acatalystwasaddedtothereactioncontainerwiththegases. Question 7 Whichoneofthefollowingstatementsiscorrectforanexothermicreaction? A. Theenthalpychangeispositive. B. Theactivationenergyisnegative. C. Heatenergyisabsorbedfromtheenvironment. D. Theenthalpyofthereactantsishigherthanthatoftheproducts. SECTION A – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

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Question 8 AnunidentifiedorganicsubstancewiththemolecularformulaC4H8O2isfoundtoreactwithabase.Mass spectrometryshowstheparentmolecularionhasamass-to-chargeratio,m/z,of88.

100 80

relative intensity

60 40 20 0

0

20

60

40

80

100

m/z Source:NISTChemistryWebBook;NISTMassSpectrometryDataCenterCollection; ©2014USSecretaryofCommerceonbehalfoftheUSA

Whichoneofthefollowingspeciesisconsistentwithapeakonthemassspectrumatm/z=45? A. [COOH]+ B. [CH3CH2O]+ C. [CH3CH2OH]+ D. [CH3CH2CH2COOH]+ Question 9 Todeterminetheconcentrationofapeptideinamixtureofpeptides,whichoneofthefollowinganalytical techniqueswouldbeused? A. high-performanceliquidchromatography B. thinlayerchromatography C. paperchromatography D. gaschromatography

SECTION A – continued

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2017CHEMISTRYEXAM(NHT)

Use the following information to answer Questions 10–12. Ammoniacanbesynthesisedbyreactingnitrogen,N2,gaswithhydrogen,H2,gasaccordingtothefollowing equation. N2(g)+3H2(g)⇌2NH3(g)   ΔH=–92kJmol–1 Question 10 Theexpressionfortheequilibriumconstantforthisreactionis [NH3 ] A. 3 [ H2 ][ N2 ] B.

2 [ NH3 ] 3 [ H2 ][ N2 ]

C.

[NH3 ]2 [ H2 ]3 [N2 ]3

D.

[NH3 ]2 [H 2 ]3 [ N2 ]

Question 11 Ifaninertgasisaddedtotheequilibriumsystemataconstanttemperatureandaconstantvolume,the concentrationofH2inthemixturewill A. increase. B. decrease. C. notchange. D. decreasethenincrease. Question 12 Therateatwhichequilibriumisestablishedcanbeloweredbyincreasingthe A. B. C. D.

temperatureofthereactionmixtureataconstantvolume. totalvolumeofthereactionvesselataconstanttemperature. concentrationofthereactantsataconstanttemperature. pressureinthereactionvesselataconstanttemperature.

Question 13 Magnesium,Mg,metalreactswithoxygen,O2,accordingtothefollowingequation. 2Mg(s)+O2(g)→2MgO(s)   ΔH=–1200kJmol–1

M(Mg)=24.3gmol–1

Forthisequation,1200kJrepresentsthe A. activationenergyforthereaction. B. heatenergyreleasedwhen2gofMgreacts. C. heatenergyreleasedwhen48.6gofMgreacts. D. heatenergyreleasedwhen1molofMgreacts.

SECTION A – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

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Question 14 100mLof0.4Mnitricacid,HNO3,isaddedto100mLof0.1Mbariumhydroxide,Ba(OH)2. ThepHoftheresultingsolutionis A. 0.3 B. 0.7 C. 0.8 D. 1.0 Question 15 Whichoneofthefollowingfactorsisleastlikelytoaffecttherateatwhichthecomponentsofagasmixture flowthroughagaschromatographycolumn? A. thelengthofthecolumn B. thetemperatureofthecolumn C. therateofflowofthecarriergas D. themolecularmassesofthegasesinthegasmixture Question 16 CH3CH2Cl

NaOH

CH3CH2OH

Reagent X

CH3COOH

CH3 CH2 CH2 OH

Product Z

Forthereactionpathwayshownabove,whichofthefollowingcorrectlyidentifiesReagentXandProductZ? Reagent X

Product Z

A.

O2

ethylethanoate

B.

H+/Cr2O7 2–

ethylpropanoate

C.

NaOH

propylpropanoate

D.

H+/MnO4–

propylethanoate

SECTION A – continued

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7

2017CHEMISTRYEXAM(NHT)

Use the following information to answer Questions 17 and 18. ThegalvaniccellshownbelowissetupunderafumehoodbyaChemistrystudentatauniversity.Chlorine gas,Cl2,iscontinuallybubbledthroughthelefthalf-cell.

V Pt electrode Cl2(g) (1 atm, 25 °C)

1 M NaCl solution (clear, 25 °C)

salt bridge Cu electrode

1 M CuSO4 solution (blue, 25 °C)

Question 17 Whenthecellbeginstooperate A. thecellvoltagewillstartat1.02V,thenslowlydrop. B. theCuelectrodewillhavepositivepolarityandactasthecathode. C. electronswillmoveoutofthePtelectrodeandalongthewiringtotheCuelectrode. D. electronswillmovethroughthesaltbridgetowardstheCuhalf-cellandcompletethecircuit. Question 18 WhatisthestudentmostlikelytoobserveintheCuhalf-cellsometimeaftertheswitchisturnedon? A. bubblesformingovertheelectrode B. theCuelectrodelookingcorroded C. thesolutionbecomingalighterblueincolour D.

crystalsofCugrowingovertheelectrode

SECTION A – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

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Question 19 Asamplecontainingamixtureoffourstraight-chainalcohols–butanol,ethanol,hexanolandpentanol–is analysedbygaschromatography.

detector response

Q

1

2

4 5 3 retention time (min)

6

Onthechromatogram,thepeakatQwasmostlikelyproducedby A. butanol. B. ethanol. C. hexanol. D. pentanol. Question 20 Someinformationgivenonthelabelsofabottleofdisinfectantisshownbelow. 500 mL

SmileyClean Powerful disinfectant

DIRECTIONS FOR HOSPITAL STANDARD DISINFECTION Use undiluted

Active ingredient

FOR GENERAL HOUSEHOLD USE

BENZALKONIUMCHLORIDE1.5%w/w

Dilute 1 part disinfectant with 20 parts water

Data • benzalkoniumchloride:C17H30ClN • density(SmileyClean):1.0gmL–1 • molarmassofC17H30ClN:283.5gmol–1 Theconcentration,inmolL–1,ofbenzalkoniumchlorideinadilutedsolutionofSmileyCleandisinfectant, readyforgeneralhouseholduse,is A. 1.5×10–2 B. 5.3×10–2 C. 2.5×10–3 D. 2.6×10–3

SECTION A – continued

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9

2017CHEMISTRYEXAM(NHT)

Question 21 Thegraphbelowrepresentsthetitrationof1.0Msodiumcarbonatesolution,Na2CO3,against1.0M hydrochloricacid,HCl.Thetitrationhastwoequivalencepoints,StageIandStageII,correspondingtothe additionofsuccessiveprotonstothebase. 14

CO32–(aq)

pH

7

Stage I CO32–(aq) + H+(aq) → HCO3–(aq)

Stage II HCO3–(aq) + H+(aq) → H2CO3(aq)

0

volume of HCl (mL)

WhichoneofthefollowingindicatorsisthemostappropriatetousetodetecttheendpointforStageII? A. phenolphthalein B. methylorange C. thymolblue D. phenolred

SECTION A – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

10

Question 22 Asealedgassyringecontainsanequilibriummixtureofbrownnitrogendioxidegas,NO2,andcolourless dinitrogentetroxidegas,N2O4.Thisisshowninthediagrambelow. gas syringe

rubber stopper

plunge r

gas mixture

Theequationforthisequilibriumreactionis N2O4(g)⇌2NO2(g)   ΔH=+57.20kJmol–1 Theplungerissuddenlypushedinattimet1,thusdecreasingthetotalvolumeofthegasmixture.The temperatureofthegasmixtureiskeptconstant. Whichoneofthefollowingconcentration–timegraphsrepresentsthechangethatoccurs? A. concentration (mol L–1)

B. NO2

concentration (mol L–1)

N2O4 t1

N2O4

time (min)

C. concentration (mol L–1)

NO2

t1

time (min)

D. NO2

concentration (mol L–1)

N2O4 t1

time (min)

NO2 N2O4 t1

time (min)

Question 23 Theequationbelowrepresentsthecompletecombustionofmethanol. 2CH3OH(l)+3O2(g)→2CO2(g)+4H2O(g) Theheatofcombustionofmethanol,inkJg–1,isclosestto A. 1450 B. 725 C. 45.31 D. 22.66

SECTION A – continued

11

2017CHEMISTRYEXAM(NHT)

Question 24 NarrowstripsofMetalXwereplacedinsolutionsoffourdifferentsaltsinseparatetesttubes.Thetable belowshowstheobservationsmadeafter10minutes. Solution

Observations

copper(II)sulfate

smallreddishcrystalsformedonMetalX;bluecolourofsolutionlightenedslightly

iron(III)chloride

solutionturnedfromayellowishcolourtoagreenishcolour

nickel(II)sulfate

smallgreyishcrystalsformedonMetalX;greencolourofsolutionlightenedslightly

aluminiumsulfate

noapparentchange

MetalXismostlikely A. silver. B. copper. C. iron. D. nickel. Question 25 Ananalystisgivenaflaskcontaininga20.0mLsolutionof0.52Mbariumchloride,BaCl2.Sheadds 25.0mLof0.75Msulfuricacid,H2SO4.Shecollectsanddriestheresultingbariumsulfateprecipitate, BaSO4.Themassofthedriedprecipitateis2.43g. WhatistheconcentrationofSO42–ions,inmolL–1,inthefiltrate? A. 0.19 B. 0.23 C. 0.33 D. 0.42 Question 26 Whenethanol,C2H5OH,reactswithalimitedamountofdichromicacid,H2Cr2O7,thereactionproduces chromium(III)ions,Cr3+,andethanal,C2H4O. Whatisthebalancedhalf-equationfortheoxidationreaction? 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)

SECTION A – continued TURN OVER

2017 CHEMISTRY EXAM (NHT)

12

Question 27 An 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.

SECTION A – continued

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

metal object to be plated

Ag electrode

AgNO3 solution

Question 28 Which 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 29 A 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 s B. 220 s C. 450 s D. 670 s

SECTION A – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

14

Question 30 Primarycells,secondarycellsandfuelcellscanallbeusedassourcesofenergy. Thefeaturesthatcanbeassociatedwithoneormoreofthethreetypesofcellsincludethefollowing: 1. Thecellisrechargeable. 2. Thecellrequiresacontinuoussupplyofreactants. 3. Reductiontakesplaceatthecathodewhendischarging. 4. Oxidationtakesplaceatthepositiveelectrodewhenrecharging. Whichoftheabovefeaturesaredisplayedbysecondarycells? A. 1,2and3 B. 2,3and4 C. 1,3and4 D. 1,2,3and4

END OF SECTION A



15

2017CHEMISTRYEXAM(NHT)

SECTION B Instructions for Section B Answerallquestionsinthespacesprovided.Writeusingblueorblackpen. Toobtainfullmarksforyourresponses,youshould: • givesimplifiedanswers,withanappropriatenumberofsignificantfigures,toallnumericalquestions; unsimplifiedanswerswillnotbegivenfullmarks • showallworkinginyouranswerstonumericalquestions;nomarkswillbegivenforanincorrect answerunlessitisaccompaniedbydetailsoftheworking • makesurechemicalequationsarebalancedandthattheformulasforindividualsubstancesincludean indicationofstate;forexample,H2(g),NaCl(s). Unlessotherwiseindicated,thediagramsinthisbookarenotdrawntoscale.

SECTION B – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

16

Question 1 (7marks) a. CompoundCmaybesynthesisedaccordingtothefollowingpathway.

Compound A Structural formula:

HCl(g)/catalyst Compound B CH3 H

C

H

CH3 H

C

Cl

Name: NH3 (ethanol) Compound C Semi-structural formula: Name:

i. DrawthestructuralformulaofCompoundAintheboxprovided.

1mark

ii. WritethesystematicnameofCompoundBintheboxprovided.

1mark

iii. Insertthesemi-structuralformulaandsystematicnameofCompoundCinthebox provided.

2marks

SECTION B – Question 1–continued



b.

17

2017CHEMISTRYEXAM(NHT)

Butan-1-ol,C4H9OH,canreactwithacidifiedpermanganateions,MnO4–,toproducebutanoic acid,C3H7COOH. i. Writeabalancedredoxhalf-equationfortheproductionofC3H7COOHfromC4H9OH.

1mark

ii. C3H7COOHreactswithethanol,C2H5OH,inthepresenceofsulfuricacid,H2SO4. 

 Nametheproductformed.

iii. Drawthestructuralformulaoftheproductnamedinpart b.ii.

1mark

1mark

SECTION B – continued TURN OVER

2017CHEMISTRYEXAM(NHT)

18

Question 2 (7marks) Glutathioneisatripeptidethatisfoundinthehumanbody.Itactsasanantioxidant,helpingto preventdamagetocells.Thesequenceforthistripeptideisglu-cys-gly. a.

Drawastructurethatrepresentsthissequenceofaminoacids,clearlyshowingthelinkages betweentheaminoacids.

b.

Glutamicacidcanbeisolatedfromasampleofglutathione.



Drawastr...