2015 Hsc Chemistry

2015 HIGHER SCHOOL CERTIFICATE EXAMINATION

1020

Chemistry

General Instructions

•Readingtime–5minutes

•Workingtime–3hours

•Writeusingblackpen

•Drawdiagramsusingpencil

•Board-approvedcalculatorsmaybeused

•AdatasheetandaPeriodicTableareprovidedatthebackofthispaper

Total marks – 100

Section I Pages2–28

75 marks

Thissectionhastwoparts,PartAandPartB

PartA–20marks

•AttemptQuestions1–20

•Allowabout35minutesforthispart

PartB–55marks

•AttemptQuestions21–30

•Allowabout1hourand40minutesforthispart

Section II Pages29–39

25 marks

•AttemptONEquestionfromQuestions31–35

•Allowabout45minutesforthissection

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Section I75 marks

Part A – 20 marksAttempt Questions 1–20Allow about 35 minutes for this part

Usethemultiple-choiceanswersheetforQuestions1–20.

1 InwhichlayeroftheatmospheredoesozoneabsorbthemostUVradiation?

(A) Mesosphere

(B) Stratosphere

(C) Thermosphere

(D) Troposphere

2 Whichtypeofglasswareisusedinatitrationtodeliveranaccuratevolumeofasolutiontoaknownvolumeofanothersolution?

(A) (B)

(C) (D)

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3 Whatflamecolourdocopperionsproducewhenheated?

(A) Brickred

(B) Blue-green

(C) Palepurple

(D) Yellow-orange

4 WhathappenstoFe2+inthefollowingreaction?

Sn4+ + Fe2+ Sn3+ + Fe3+

(A) Itundergoesoxidationandgainselectrons.

(B) Itundergoesreductionandgainselectrons.

(C) Itundergoesoxidationandloseselectrons.

(D) Itundergoesreductionandloseselectrons.

5 The oxides CaO, CO2, Na2O and N2O4 are placed in water to form four separatesolutions.

Which row of the table correctly indicates the solutions with pH less than 7 and thesolutionswithpHgreaterthan7?

Solutions

pH less than 7 pH greater than 7

(A) CO2 N2O4 CaO Na2O

(B) CaO N2O4 CO2 Na2O

(C) CaO Na2O CO2 N2O4

(D) CO2 Na2O CaO N2O4

6 WhichofthefollowingisthemostsuitablereplacementforCFCsintermsofreducingtheirenvironmentalimpact?

(A) CH4

(B) CH2F2

(C) CH2ClF

(D) CHCl2CCl2F

–4–

7 Adiagramofasimplecellisshown.

CuAg

Ag+(aq)Ag+(aq) Cu2+(aq)Cu2+(aq)

V

Salt bridge

Whichofthefollowingoccurswhenthecellisinoperation?

(A) Silverionsareformedinsolution.

(B) Thecopperelectrodeloseselectrons.

(C) Electronstravelthroughtheelectrolyte.

(D) Thecopperelectrodeincreasesinmass.

8 Whichofthefollowingstatementsbestexplainsthesolubilityofethanolinoctane?

(A) Ethanolandoctanearebothnon-polar.

(B) Ethanolformshydrogenbondswithoctane.

(C) Ethanolformsdispersionforceswithoctane.

(D) Ethanolformsdipole-dipolebondswithoctane.

9 Whatarethereactantsusedtomakethiscompound?

CH3CH2CH2 C

O

O CH2CH2CH3

(A) Butan-1-olandbutanoicacid

(B) Butan-1-olandpropanoicacid

(C) Propan-1-olandbutanoicacid

(D) Propan-1-olandpropanoicacid

– 5 –

10 Which of the equations correctly describes incomplete combustion?

(A) C2H5OH(l) + 2O2(g) 2CO(g) + 3H O(l2 )

(B) C OH(l) + 7O g g l2H5 2 2( ) 2CO2( ) + 3H2O( )

(C) C2H5OH(l) + 3O2(g) 2CO2(g) + 3H O(l2 )

(D) C OH(l) + 2O g s g l2H5 2( ) C( ) + CO( ) + 3H2O( )

11 Two monomers are shown.

C(C)

H

C

H n

C

H H

O O C

O O

(CH2)2C O

H

C OH

H

C

H H

HO OHC

O

C

O

HO (CH2)2

HO(B)

H

C

H

C

H H

O C

O O

(CH2)2C OH

n

O(D)

H

C

H

C

H H

O C

O O

(CH2)2C

n

(A)

H

C

H

C

H H

C

O O

(CH2)2C

Which of the following shows a condensation polymer that could be formed from the monomers?

(A)

nH

C

H

C

H H

C

O O

(CH2)2C

(B)

H H O O

HO C C O C (CH2) C OH2

H H

(C)

H H O O

C C C O O C (CH2) C O2

H H n

H

C OH

H

C

H H

HO OHC

O

C

O

HO (CH2)2

(D)

n

O

H

C

H

C

H H

O C

O O

(CH2)2C

–6–

12 Atransuranicelementcanbeproducedinanuclearreactoraccordingtothisequation:

23994Pu + 2X 241Pu 241

94 95Am + Y

WhichrowofthetablecorrectlyidentifiesXandY?

X Y

(A) Neutron Electron

(B) Proton Neutron

(C) Neutron Proton

(D) Proton Electron

13 WhichofthefollowingsolutionshasthehighestpH?

(A) 1.0molL−1 aceticacid

(B) 0.10molL−1 aceticacid

(C) 1.0molL−1 hydrochloricacid

(D) 0.10molL−1 hydrochloricacid

14 ThegraphshowsthechangesinpHduringatitration.

0

2

6

10

14

4

8pH

12

Volume (mL)

WhichpHrangeshouldanindicatorhavetobeusedinthistitration?

(A) 3.1–4.4

(B) 5.0–8.0

(C) 6.0–7.6

(D) 8.3–10.0

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15 Partofawatercatchmentisshowninthediagram.

Stream

River

Forest

Ocean

Village

Farmland

1 km

X

AsampleofriverwatertakenfrompointXisanalysed.

Whichrowofthetableshowsthemostlikelyresults?

ResultsofwateranalysisatX

Turbidity (NTU)

BOD(ppm)

pH Total dissolved solids (ppm)

(A) 400 18 6.5 22 000

(B) 22 3 8.5 17

(C) 5 18 6.5 22 000

(D) 400 3 8.5 17

16 Theequationdescribesanequilibriumreactionoccurringinaclosedsystem.

X(g) + Y(g) 4Z(g) DH=+58kJ

UnderwhichsetofconditionswouldthehighestyieldofZ(g)beobtained?

Temperature (°C) Pressure (kPa)

(A) 50 100

(B) 50 200

(C) 300 100

(D) 300 200

–8–

17 Whatvolumeofcarbondioxidewillbeproduced if10.3gofglucose is fermentedat25°Cand100kPa?

(A) 1.30L

(B) 1.42L

(C) 2.57L

(D) 2.83L

UsethisinformationtoanswerQuestions18–19.

A sample of pond water from a contaminated site was analysed to determine theconcentrationofleadionsusingthefollowingprocedure.

• Ameasuringcylinderwasusedtocollecta50mLsamplefromthepond.

• Thesamplewasplacedinacleandrybeaker.

• 25.0mLof0.200molL−1sodiumchloridesolutionwasaddedtothesample.

• Theprecipitateoflead(II)chloridethatformedwasfiltered,driedandweighed.Ithadamassof0.13g.

18 Howcouldthereliabilityoftheanalysisofthepondwaterbeimproved?

(A) Analysemoresamplesfromthesamepond

(B) Use50mLofdistilledwaterasacontrolsample

(C) Analysesamplesfromdifferentpondsonthesite

(D) Removeothercontaminantsfromthesamplebeforetheanalysis

19 Whatwastheconcentrationofleadionsinthesample?

(A) 5.0×10−3molL−1

(B) 5.8×10−3molL−1

(C) 9.3×10−3molL−1

(D) 10.7×10−3molL−1

–9–

20 Thetableshowstheheatofcombustionoffourstraightchainalkanols.

Number of C atoms in straight chain alkanol

Heat of combustion (kJmol–1)

1 726

3 2021

5 3331

7 4638

What is the mass of water that could be heated from 20°C to 45°C by the completecombustionof1.0gofheptan-1-ol?

(A) 0.032kg

(B) 0.044kg

(C) 0.36kg

(D) 0.38kg

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© 2015 Board of Studies, Teaching and Educational Standards NSW

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Centre Number

Student Number

43933103511021 15050


Chemistry

Section I (continued)

Part B – 55 marksAttempt Questions 21–30Allow about 1 hour and 40 minutes for this part

Answer the questions in the spacesprovided. These spaces provideguidance for the expected length ofresponse.

Showallrelevantworkinginquestionsinvolvingcalculations.

Extra writing space is provided onpages27and28.Ifyouusethisspace,clearly indicate which question youareanswering.

Write your Centre Number andStudent Number at the top of thispage.

Please turn over

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2381310356

Question 21 (4marks)

(a) Outlineasuitablemethodtoprepareanaturalindicator.

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(b) Howcouldanaturalindicatorbetested?

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Thetableshowsdataforozoneconcentrationsover50yearsintheupperatmosphereaboveAntarctica.

Year Ozone Concentration (DobsonUnits)

1955196019701980199520002005

320300300260130130150

(a) Drawalinegraphofthedataonthegridprovided. 4

Question 22 continues on page 16

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4873310354

Question22(continued)

(b) Describeamethodbywhichthisdatacouldhavebeenmeasured.

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7471310351

Question 23 (4 marks)

Explain how the structure and chemistry of ONE of the following cells determines its cost and practicality.

• button cell

• fuel cell

• vanadium redox cell

• lithium cell

• liquid junction photovoltaic device (eg the Gratzel cell)

4

Name of cell: ...........................................................................................................

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9964310350


(a) Explainwhythesalt,sodiumacetate,formsabasicsolutionwhendissolvedinwater.Includeanequationinyouranswer.

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(b) Asolutionispreparedbyusingequalvolumesandconcentrationsofaceticacidandsodiumacetate.

ExplainhowthepHofthissolutionwouldbeaffectedbytheadditionofasmallamountofsodiumhydroxidesolution.Includeanequationinyouranswer.

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(a) Describe the steps involved in the process of addition polymerisation.

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(b) Explain the uses of polyethylene and polystyrene in terms of their structures and properties.

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9657310359


A sodium hydroxide solution was titrated against citric acid (C6H8O7) which istriprotic.

(a) Drawthestructuralformulaofcitricacid(2−hydroxypropane−1,2,3−tricarboxylicacid).

1

(b) How could a computer-based technology be used to identify the equivalencepointofthistitration?

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6157310351

Question 26 (continued)

(c) The sodium hydroxide solution was titrated against 25.0 mL samples of 0.100 mol L−1 citric acid. The average volume of sodium hydroxide used was 41.50 mL.

Calculate the concentration of the sodium hydroxide solution.

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Namearadioisotopeusedinanon-medicalindustryanddiscussitsuseinthatindustryintermsofitsproperties.

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6784310357


The equipment shown is set up. After some time a ring of white powder is seen to form on the inside of the glass tube.

Cotton woolsoaked in

concentratedhydrochloric

acid

Cotton woolsoaked in

concentratedammonia

Glass tube

Ring ofwhite

powder

(a) Why would this NOT be an acid–base reaction according to Arrhenius?

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(b) Explain why this would be considered a Brönsted–Lowry acid–base reaction. Include an equation in your answer.

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7927310357


The procedure of a first-hand investigation conducted in a school laboratory todeterminethepercentageofsulfateinalawnfertiliserisshown.

• 2.00gofasampleoffertiliserwasgroundupandplacedinabeaker.

• Itwasdissolvedinabout200mLof0.1molL−1hydrochloricacid,stirredandfiltered.

• Excessbariumchloridesolutionwasquicklyaddedtothisbeakerandaprecipitateformed.

• Theprecipitatewasthenallowedtosettle,filteredusingfilterpaperandtheresiduecollected.

• Theresiduewasdriedandweighedandhadamassof2.23g.

(a) Suggest modifications that could be made to the procedure to improve theresultsofthisinvestigation.Justifyyoursuggestions.

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9403310358

Question 29 (continued)

(b) Calculate the percentage of sulfate in the original fertiliser sample.

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8246310352


The graph shows the percentage yield of ammonia produced from nitrogen andhydrogenatdifferenttemperaturesandpressures.

6

Temperature (°C)

Perc

enta

ge y

ield

of

amm

onia

200 300 400 500 600

90

60

30

0

Pressure

500 atm

400 atm

300 atm

200 atm

TheHaberprocessis themainindustrialprocedurefor theproductionofammonia.ExplaintheconditionsusedintheHaberprocesswithreferencetothegraph.

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9248310355

Section I Part B extra writing space

If you use this space, clearly indicate which question you are answering.

DoN

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8455310354OfficeUseOnly–DoNOTwriteanything,ormakeanymarksbelowthisline.

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Section I Part B extra writing space

If you use this space, clearly indicate which question you are answering.

©2015BoardofStudies,TeachingandEducationalStandardsNSW

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Chemistry

Section II

25 marksAttempt ONE question from Questions 31–35Allow about 45 minutes for this section

Answerparts(a)–(d)ofonequestionintheSectionIIWritingBooklet.Extrawritingbookletsareavailable.

Showallrelevantworkinginquestionsinvolvingcalculations.

Pages

Question31 IndustrialChemistry...............................................................30–31

Question32 Shipwrecks,CorrosionandConservation..............................32–33

Question33 TheBiochemistryofMovement............................................34–35

Question34 TheChemistryofArt.............................................................36–37

Question35 ForensicChemistry................................................................38–39

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Question 31 — Industrial Chemistry (25marks)

Answer parts (a) and (b) of the question on pages 2–4 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.

(a) At temperatures above 100°C, hydrogen and carbon monoxide react to formmethanolgasinthisreversiblereaction.

2H2(g)+CO(g)CH3OH(g)

Amixtureofhydrogen,carbonmonoxideandmethanolisplacedinacontainerwithavolumethatcanbechanged.Themixtureisallowedtoreachequilibrium.

(i) Theinitialvolumeofthecontaineris1.00L.

Accountforanychangesintheconcentrationofhydrogengaswhenthevolumeofthecontainerisrapidlyincreasedto2.00L.

2

(ii) The initialmixtureplaced in thecontainerhad0.50molofhydrogen,1.00 mol of carbon monoxide and 2.50 mol of methanol. Once thevolumeof thecontainerhadbeen increased to2.00Landequilibriumhadbeenre-established,thenumberofmolesofhydrogeninthemixturehadchangedby0.36mol.

Calculatetheequilibriumconstantforthisreaction.

3

(b) (i) Describe how saponification can be safely carried out as part of afirst-handinvestigation.

3

(ii) Explainthechemistryrelatedtothecleaningpropertiesoftheproductofsaponification.

4


–31–


Answer parts (c) and (d) of the question on pages 5–8 of the Section II WritingBooklet.Starteachpartofthequestiononanewpage.

(c) ThediagramshowspartoftheSolvayprocessforproducingsodiumcarbonate.

Purifiedbrine

Carbondioxide

Ammonia

Reactionvessel

Cooled Filtered Heated Sodiumcarbonate

Calciumchloride

(i) Outline the chemistry of the production of sodium carbonate in theprocessshown.Includeequationsinyouranswer.

3

(ii) Bymakingspecificreferencetothediagram,justifytherequirementsforthelocationofaSolvayprocessplant.

3

(d) Compare the membrane cell method with ONE other method used inthe industrial production of sodium hydroxide in terms of technical andenvironmentalissues.

7

End of Question 31

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Question 32 — Shipwrecks, Corrosion and Conservation (25marks)


(a) (i) Outlinethelimitationsofusingpainttoprotectshipsthatareinconstantuse.

2

(ii) Explainthechemicalprinciplesinvolvedintheuseofasacrificialanode.Includerelevantchemicalequationsinyouranswer.

3

(b) (i) Describeavalidandreliablefirst-handinvestigationthatcanbeusedtocomparetheratesofcorrosionofironwithONEnamedformofsteel.

3

(ii) Explain how the percentage composition of steel can determine itsproperties,withreferencetoTWOtypesofsteel.

4


–33–



(c) (i) Theequipmentinthephotographwasusedinanattempttoplateametalspoonwithmagnesiumusinganelectrolyticcellcontainingasolutionofmagnesiumsulfate.

3

Mg(s)

Drawa labelled scientificdiagramof the electrolytic cell. Include thecathode,anode,directionofelectronflowandpolarityoftheelectrodes.

(ii) Explain how Davy’s work increased our understanding of electrontransferreactions.

3

(d) Twoidenticalshipsaresunkinseawater.Oneissunkinshallowwater(60m)andtheotherindeepwater(4000m).Explainhowtherustingprocessesdifferinthesetwoships.Includeequationsinyouranswer.

7

End of Question 32

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Question 33 — The Biochemistry of Movement (25marks)


(a) (i) Asimplifieddiagramofamusclecellisshown. 2

IdentifytheTWOcomponentsofthecellthatareinvolvedinrespirationANDthetypeofrespirationthatoccursineach.

(ii) Explain the biological significance of adenosine triphosphate (ATP)withreferencetoitsstructure.

3

(b) (i) Describe a reliable and valid procedure that can be carried out todemonstratetheeffectofchangingtemperatureonenzymefunction.

3

(ii) Discuss the use of models in understanding how enzymes function inlivingsystems.

4


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(c) Asectionofaproteinisshown.

CH

CH3

CH2CH3CH

CH3

CH3

NH3+

NH3+

COO–

CH2CH2

CH2CH2

C

O

S S

O

O

H

CN

H

(i) UsingTWOexamplesfromthediagram,explainhowbondingbetweensectionsoftheproteinchaininfluencesitsshape.

3

(ii) With reference to thediagram,account forways inwhich thisproteinmaybedenatured.

3

(d) Compare the metabolic pathways involved in sprinting with those involvedwhenwalkingatagentlepace.

7

End of Question 33

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Question 34 — The Chemistry of Art (25marks)


(a) (i) Identify the chemical composition of a cosmetic used in an ancientcultureandidentifythepotentialhealthriskassociatedwiththeuseofthecosmetic.

2

(ii) ExplainwhyCr2+(aq)iscolouredwhereasZn2+(aq)isnotcoloured. 3

(b) Aninvestigationistobeconductedtoobservetheflamecolourofsomemetalions.

(i) Describea safeandvalidprocedure thatcanbeused tocarryout thisinvestigation,identifyingthespecificmetalionsobserved.

3

(ii) Explain why only certain metal ions can be identified using flamecolours, naming ONE metal ion that cannot be identified using flamecolours.

4


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(c) (i) ThefirstionisationenergyofeachoftheelementsinthethirdrowofthePeriodicTableisgiven.

3

Element Na Mg Al Si P S Cl Ar

Firstionisationenergy(kJmol–1)

494 736 577 786 1060 1000 1260 1520

Use thedata in the table to explainhow the first ionisationenergyoftheseelementscanprovideevidence for theexistenceof sub-shells inatoms.

(ii) ThegraphshowstheelectronegativityvaluesforelementsinPeriods1,2and3ofthePeriodicTable.

0

1.0

2.0

3.0

4.0

2 4 6 8 10

Atomic Number

Ele

ctro

nega

tivity

(P

aulin

g sc

ale)

12 14 16 18 20

Use the graph to explain the relationship between the arrangement ofelectronsinanelementanditselectronegativity.

3

(d) AssesshowtheBohrmodeloftheatomhascontributedtoourunderstandingofatomicstructure,makingreferencetoemissionspectra.

7

End of Question 34

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Question 35 — Forensic Chemistry (25marks)


(a) (i) Comparethecompositionofglycogenwiththatofcellulose. 2

(ii) Relatethedifferencesincompositionofglycogenandcellulosetotheirdifferentstructures.

3

(b) (i) Identify the structure of amino acids and describe the relationshipbetweenaminoacidsandproteins.

3

(ii) Describeasafeandvalidprocedurethatcanbeusedtoshowthepresenceofproteinineggwhite.Includeexpectedresults.

4


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(c) (i) GeorgeandLindahaveonechild together.Eachof themalsohasonechildfromapreviousrelationship.Aschematicrepresentationof theirDNAprofilesisshownbelow.

3

George Linda Child A

Child B

Child C

DNA profiles obtained from George, Linda and the three children

UsetheinformationintheDNAprofilestoidentifytherelationshipsofChildA,ChildBandChildCtoGeorgeandLinda.Justifyyouranswer.

(ii) DescribethebenefitsofmaintainingDNAdatabanks. 3

(d) Name ONE chromatography technique and assess its use in the analysis offorensicevidence.

7

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© 2015 Board of Studies, Teaching and Educational Standards NSW

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1023


Chemistry

DATA SHEET

Avogadroconstant,NA................................................................... 6.022×1023mol–1

Volumeof1moleidealgas:at100kPaandat0°C(273.15K)....................... 22.71Lat25°C(298.15K)..................... 24.79L

Ionisationconstantforwaterat25°C(298.15K),Kw.................. 1.0×10–14

Specificheatcapacityofwater...................................................... 4.18×103Jkg–1K–1

Some useful formulae

pH=– log10[H+] DH=–mCDT

Some standard potentials

AylwardandFindlay,SI Chemical Data(5thEdition)istheprincipalsourceofdataforthisexaminationpaper.Somedatamayhavebeenmodifiedforexaminationpurposes.

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Documents

2015 Hsc Chemistry